path: root/doc/book/src/Programming-In-Apache-Qpid.xml

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<book id="client-api-tutorial">
  <title>Programming in Apache Qpid</title>
  <subtitle>Cross-Platform AMQP Messaging in Java JMS, .NET, C++, and Python</subtitle>

  <chapter>
    <title>Introduction</title>
    
    <para>Apache Qpid is a reliable, asynchronous messaging system that
      supports the AMQP messaging protocol in several common programming
      languages. Qpid is supported on most common platforms.
    </para>

    <itemizedlist>
      <listitem>
        <para>
          On the Java platform, Qpid uses the
          established <ulink url="http://java.sun.com/products/jms/">Java JMS
            API</ulink>. 
        </para>
      </listitem>
      <listitem>
        <para>
          On the .NET platform, Qpid defines
          a <ulink url="http://qpid.apache.org/wcf.html">WCF
            binding</ulink>.
        </para>
      </listitem>
      <listitem>
        <para>
          For Python and C++, Qpid defines its own messaging API, the
          <firstterm>Qpid Messaging API</firstterm>, which is
          conceptually similar in each supported language.
        </para>
      </listitem>
      <listitem>
        <para>
          Support for this API in Ruby will be added
          soon (Ruby currently uses an API that is closely
	  tied to the AMQP version).
        </para>
      </listitem>
    </itemizedlist>
  </chapter>

  <chapter>
    <title>Using the Qpid Messaging API</title>

    <para>The Qpid Messaging API is quite simple, consisting of only a
      handful of core classes.
    </para>

    <itemizedlist>

      <listitem>
        <para>
          A <firstterm>message</firstterm> consists of a standard set
          of fields (e.g. <literal>subject</literal>,
          <literal>reply-to</literal>), an application-defined set of
          properties, and message content (the main body of the
          message).
        </para>
      </listitem>
      
      <listitem>
        <para>
          A <firstterm>connection</firstterm> represents a network
          connection to a remote endpoint.
        </para>
      </listitem>
      
      <listitem>
        <para>
          A <firstterm>session</firstterm> provides a sequentially
          ordered context for sending and receiving
          <emphasis>messages</emphasis>. A session is obtained from a
          connection.
        </para>
      </listitem>
      
      <listitem>
        <para>
	  A <firstterm>sender</firstterm> sends messages to a target
	  using the <literal>sender.send</literal> method. A sender is
	  obtained from a session for a given target address.
        </para>
      </listitem>
      
      <listitem>
        <para>
	  A <firstterm>receiver</firstterm> receives messages from a
	  source using the <literal>receiver.fetch</literal> method.
	  A receiver is obtained from a session for a given source
	  address.
        </para>
      </listitem>
      
    </itemizedlist>

    <para>
      The following sections show how to use these classes in a
      simple messaging program.
    </para>

    <section>
      <title>A Simple Messaging Program in C++</title>

      <para>The following C++ program shows how to create a connection,
        create a session, send messages using a sender, and receive
        messages using a receiver.</para>

	<example>
	  <title>"Hello world!" in C++</title>
	  <programlisting lang="c++"><![CDATA[
#include <qpid/messaging/Connection.h>
#include <qpid/messaging/Message.h>
#include <qpid/messaging/Receiver.h>
#include <qpid/messaging/Sender.h>
#include <qpid/messaging/Session.h>

#include <iostream>

using namespace qpid::messaging;

int main(int argc, char** argv) {
    std::string broker = argc > 1 ? argv[1] : "localhost:5672";
    std::string address = argc > 2 ? argv[2] : "amq.topic";
    Connection connection(broker);
    try {
        connection.open();
        Session session = connection.createSession();

        Receiver receiver = session.createReceiver(address);
        Sender sender = session.createSender(address);

        sender.send(Message("Hello world!"));

        Message message = receiver.fetch(Duration::SECOND * 1);
        std::cout << message.getContent() << std::endl;
        session.acknowledge();
        
        connection.close();
        return 0;
    } catch(const std::exception& error) {
        std::cerr << error.what() << std::endl;
        connection.close();
        return 1;   
    }
}]]></programlisting>
      </example>


    </section>

    <section>
      <title>A Simple Messaging Program in Python</title>

      <para>The following Python program shows how to create a
        connection, create a session, send messages using a sender, and
        receive messages using a receiver.</para>

	<example>
	  <title>"Hello world!" in Python</title>
	  <programlisting lang="python"><![CDATA[
import sys
from qpid.messaging import *

broker =  "localhost:5672" if len(sys.argv)<2 else sys.argv[1]
address = "amq.topic" if len(sys.argv)<3 else sys.argv[2]

connection = Connection(broker)

try:
  connection.open()
  session = connection.session()

  sender = session.sender(address)
  receiver = session.receiver(address)

  sender.send(Message("Hello world!"));

  message = receiver.fetch(timeout=1)
  print message.content
  session.acknowledge() # acknowledge message receipt

except MessagingError,m:
  print m
finally:
  connection.close()
]]></programlisting>
	</example>

    </section>
    <section id="section-addresses">
      <title>Addresses</title>
      
      <para>An <firstterm>address</firstterm> is the name of a message
      target or message source. In the programs we have just seen, we
      used the address <literal>amq.topic</literal> (which is the name
      of an exchange on an AMQP 0-10 messaging broker).
      
      The methods that create senders and receivers require an
      address. The details of sending to a particular target or
      receiving from a particular source are then handled by the
      sender or receiver. A different target or source can be used
      simply by using a different address.
      </para>

      <para>An address resolves to a <firstterm>node</firstterm>. The
      Qpid Messaging API recognises two kinds of nodes,
      <firstterm>queues</firstterm> and <firstterm>topics</firstterm>

	   <footnote><para>The terms <emphasis>queue</emphasis> and
	   <emphasis>topic</emphasis> here were chosen to align with
	   their meaning in JMS. These two addressing 'patterns',
	   queue and topic, are sometimes refered as point-to-point
	   and publish-subscribe. AMQP 0-10 has an exchange type
	   called a <emphasis>topic exchange</emphasis>. When the term
	   <emphasis>topic</emphasis> occurs alone, it refers to a
	   Messaging API topic, not the topic
	   exchange.</para></footnote>.

      A queue stores each message until it has been received and
      acknowledged, and only one receiver can receive a given message
      <footnote><para>There are exceptions to this rule; for instance,
      a receiver can use <literal>browse</literal> mode, which leaves
      messages on the queue for other receivers to
      read.</para></footnote>

      A topic immediately delivers a message to all eligible
      receivers; if there are no eligible receivers, it discards the
      message.  In the AMQP 0-10 implementation of the API,
      
          <footnote><para>The AMQP 0-10 implementation is the only one
          that currently exists.</para></footnote>

      queues map to AMQP queues, and topics map to AMQP exchanges.

          <footnote><para>In AMQP 0-10, messages are sent to
          exchanges, and read from queues. The Messaging API also
          allows a sender to send messages to a queue; internally,
          Qpid implements this by sending the message to the default
          exchange, with the name of the queue as the routing key. The
          Messaging API also allows a receiver to receive messages
          from a topic; internally, Qpid implements this by setting up
          a private subscription queue for the receiver and binding
          the subscription queue to the exchange that corresponds to
          the topic.</para></footnote>
      </para>

      <para>In the rest of this tutorial, we present many examples
      using two programs that take an address as a command line
      parameter.  <command>spout</command> sends messages to the
      target address, <command>drain</command> receives messages from
      the source address.  The source code is available in both C++
      and Python, and can be found in the examples directory for each
      language. These programs can use any address string as a source
      or a destination, and have many command line options to
      configure behavior&mdash;use the <command>-h</command> option
      for documentation on these options. 

      <footnote><para>Currently, the Python and C++
      implementations of <command>drain</command> and
      <command>spout</command> have slightly different
      options. This tutorial uses the C++ implementation. The
      options will be reconciled in the near
      future.</para></footnote>


      The examples in this tutorial also use the
      <command>qpid-config</command> utility to configure AMQP 0-10
      queues and exchanges on a Qpid broker.
      </para>


      <example>
        <title>Queues</title>

        <para>Create a queue with <command>qpid-config</command>, send a message using
          <command>spout</command>, and read it using <command>drain</command>:</para>

        <screen>
$ qpid-config add queue hello-world
$ ./spout hello-world
$ ./drain hello-world

Message(properties={spout-id:c877e622-d57b-4df2-bf3e-6014c68da0ea:0}, content='')
        </screen>

        <para>The queue stored the message sent by <command>spout</command> and delivered
        it to <command>drain</command> when requested.</para>

	<para>Once the message has been delivered and and acknowledged
	by <command>drain</command>, it is no longer available on the queue. If we run
	<command>drain</command> one more time, no messages will be retrieved.</para>

        <screen>
$ ./drain hello-world
$
	</screen>

      </example>

      <example>
	<title>Topics</title>

	<para>This example is similar to the previous example, but it
	uses a topic instead of a queue.</para>

	<para>First, use <command>qpid-config</command> to remove the queue
	and create an exchange with the same name:</para>

        <screen>
$ qpid-config del queue hello-world
$ qpid-config add exchange topic hello-world
        </screen>

	<para>Now run <command>drain</command> and <command>spout</command> the same way we did in the previous example:</para>

	<screen>
$ ./spout hello-world
$ ./drain hello-world
$
        </screen>

        <para>Topics deliver messages immediately to any interested
        receiver, and do not store messages. Because there were no
        receivers at the time <command>spout</command> sent the
        message, it was simply discarded. When we ran
        <command>drain</command>, there were no messages to
        receive.</para>

	<para>Now let's run <command>drain</command> first, using the
	<literal>-t</literal> option to specify a timeout in seconds.
	While <command>drain</command> is waiting for messages,
	run <command>spout</command> in another window.</para>

        <para><emphasis>First Window:</emphasis></para>

        <screen>
$ ./drain -t 30 hello-word
        </screen>
        

        <para><emphasis>Second Window:</emphasis></para>

        <screen>
$ ./spout hello-word
        </screen>

        <para>Once <command>spout</command> has sent a message, return
          to the first window to see the output from
          <command>drain</command>:</para>

        <screen>
Message(properties={spout-id:7da2d27d-93e6-4803-8a61-536d87b8d93f:0}, content='')
        </screen>

        <para>You can run <command>drain</command> in several separate
          windows; each creates a subscription for the exchange, and
          each receives all messages sent to the exchange.</para>

      </example>

      <section>
	<title>Address Strings</title>

	<para>So far, our examples have used address strings that
	contain only the name of a node. An <firstterm>address
	string</firstterm> can also contain a
	<firstterm>subject</firstterm> and
	<firstterm>options</firstterm>.</para>
      
	<para>The syntax for an address string is:</para>
      
	<programlisting><![CDATA[
address_string ::=  <address> [ / <subject> ] [ ; <options> ]
options ::=  { <key> : <value>, ... }
]]></programlisting>
      
	<para>Addresses, subjects, and keys are strings.  Values can
	be numbers, strings (with optional single or double quotes),
	maps, or lists. A complete BNF for address strings appears in
	<xref linkend="section-address-string-bnf"/>.</para>


	<para>So far, the address strings in this tutorial have used
	only addresses. The following sections show how to use
	subjects and options.</para>

      </section>

      <section>
	<title>Subjects</title>


	<para>Every message has a property called
	<firstterm>subject</firstterm>, which is analogous to the
	subject on an email message. If no subject is specified, the
	message's subject is null. For convenience, address strings
	also allow a subject. If a sender's address contains a
	subject, it is used as the default subject for the messages
	it sends. 

	If a receiver's address contains a subject, it is used to
	select only messages that match the subject&mdash;the matching
	algorithm depends on the message source.
      </para>

      <para>
	In AMQP 0-10, each exchange type has its own matching
	algorithm, and queues do not provide filtering. This is
	discussed in <xref linkend="section-amqp0-10-mapping"/>.
      </para>

      <note>
	<para>
	  Currently, a receiver bound to a queue ignores subjects,
	  receiving messages from the queue without filtering.

	  In the future, if a receiver is bound to a queue, and its
	  address contains a subject, the subject will be used as a
	  selector to filter messages.
	</para>
      </note>


      <example>
        <title>Using subjects</title>

        <para>In this example we show how subjects affect message
        flow.</para>

        <para>First, let's use <command>qpid-config</command> to create a topic exchange.</para>

        <screen>
$ qpid-config add exchange topic news-service
        </screen>

        <para>Now we use drain to receive messages from <literal>news-service</literal> that match the subject <literal>sports</literal>.</para>
        <para><emphasis>First Window:</emphasis></para>
        <screen>
$ ./drain -t 30 news-service/sports
        </screen>

        <para>In a second window, let's send messages to <literal>news-service</literal> using two different subjects:</para>

        <para><emphasis>Second Window:</emphasis></para>
        <screen>
$ ./spout news-service/sports
$ ./spout news-service/news
        </screen>

        <para>Now look at the first window, the message with the
        subject <literal>sports</literal> has been received, but not
        the message with the subject <literal>news</literal>:</para>

        <screen>
Message(properties={qpid.subject:sports, spout-id:9441674e-a157-4780-a78e-f7ccea998291:0}, content='')
        </screen>

        <para>If you run <command>drain</command> in multiple
          windows using the same subject, all instances of
          <command>drain</command> receive the messages for that
          subject.</para>
      </example>
        

        <para>The AMQP exchange type we are using here,
        <literal>amq.topic</literal>, can also do more sophisticated
        matching.

	A sender's subject can contain multiple words separated by a
	<quote>.</quote> delimiter. For instance, in a news
	application, the sender might use subjects like
	<literal>usa.news</literal>, <literal>usa.weather</literal>,
	<literal>europe.news</literal>, or
	<literal>europe.weather</literal>. 

	The receiver's subject can include wildcard characters&mdash;
	<quote>#</quote> matches one or more words in the message's
	subject, <quote>*</quote> matches a single word. 

	For instance, if the subject in the source address is
	<literal>*.news</literal>, it matches messages with the
	subject <literal>europe.news</literal> or
	<literal>usa.news</literal>; if it is
	<literal>europe.#</literal>, it matches messages with subjects
	like <literal>europe.news</literal> or
	<literal>europe.pseudo.news</literal>.</para>

	  <example>
	    <title>Subjects with multi-word keys</title>

	    <para>This example uses drain and spout to demonstrate the
	    use of subjects with two-word keys.</para>

	    <para>Let's use <command>drain</command> with the subject
	    <literal>*.news</literal> to listen for messages in which
	    the second word of the key is
	    <literal>news</literal>.</para>

	    <para><emphasis>First Window:</emphasis></para>
	
	    <screen>
$ ./drain -t 30 news-service/*.news
	    </screen>

	    <para>Now let's send messages using several different
	    two-word keys:</para>

	    <para><emphasis>Second Window:</emphasis></para>

	    <screen>
$ ./spout news-service/usa.news
$ ./spout news-service/usa.sports
$ ./spout news-service/europe.sports
$ ./spout news-service/europe.news
	    </screen>

	    <para>In the first window, the messages with
	    <literal>news</literal> in the second word of the key have
	    been received:</para>

	    <screen>
Message(properties={qpid.subject:usa.news, spout-id:73fc8058-5af6-407c-9166-b49a9076097a:0}, content='')
Message(properties={qpid.subject:europe.news, spout-id:f72815aa-7be4-4944-99fd-c64c9747a876:0}, content='')
	    </screen>


	    <para>Next, let's use <command>drain</command> with the
	    subject <literal>#.news</literal> to match any sequence of
	    words that ends with <literal>news</literal>.</para>

	    <para><emphasis>First Window:</emphasis></para>

	    <screen>
$ ./drain -t 30 news-service/#.news
	    </screen>

	    <para>In the second window, let's send messages using a
	    variety of different multi-word keys:</para>

	    <para><emphasis>Second Window:</emphasis></para>

	    <screen>
$ ./spout news-service/news
$ ./spout news-service/sports
$ ./spout news-service/usa.news
$ ./spout news-service/usa.sports
$ ./spout news-service/usa.faux.news
$ ./spout news-service/usa.faux.sports
	    </screen>

        <para>In the first window, messages with
        <literal>news</literal> in the last word of the key have been
        received:</para>

        <screen>
Message(properties={qpid.subject:news, spout-id:cbd42b0f-c87b-4088-8206-26d7627c9640:0}, content='')
Message(properties={qpid.subject:usa.news, spout-id:234a78d7-daeb-4826-90e1-1c6540781eac:0}, content='')
Message(properties={qpid.subject:usa.faux.news, spout-id:6029430a-cfcb-4700-8e9b-cbe4a81fca5f:0}, content='')
        </screen>
      </example>

    </section>

    <section>
      <title>Address String Options</title>

      <para>
        The options in an address string contain additional
        information for the senders or receivers created for it,
        including:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            Policies for assertions about the node to which an address
            refers.
	  </para>
	  <para>
	    For instance, in the address string <literal>my-queue;
	    {assert: always, node:{ type: queue }}</literal>, the node
	    named <literal>my-queue</literal> must be a queue; if not,
	    the address does not resolve to a node, and an exception
	    is raised.
          </para>
        </listitem>
        <listitem>
          <para>
            Policies for automatically creating or deleting the node to which an address refers.
	  </para>
	  <para>
	    For instance, in the address string <literal>xoxox ; {create: always}</literal>, 
	    the queue <literal>xoxox</literal> is created, if it does
	    not exist, before the address is resolved.
          </para>
        </listitem>
        <listitem>
          <para>
            Extension points that can be used for sender/receiver configuration.
	  </para>
	  <para>
	    For instance, if the address for a receiver is
	    <literal>my-queue; {mode: browse}</literal>, the receiver
	    works in <literal>browse</literal> mode, leaving messages
	    on the queue so other receivers can receive them.
          </para>
        </listitem>
      </itemizedlist>


      <para>
        Let's use some examples to show how these different kinds of
        address string options affect the behavior of senders and
        receives.
      </para>
      
      
      <para>
	First, let's use the <literal>assert</literal> option to
	ensure that the address resolves to a node of the required
	type.
      </para>


      <example>
	<title>Assertions on Nodes</title>

	<para>Let's use <command>qpid-config</command> to create a
        queue and a topic.</para>

	<screen>
$ qpid-config add queue my-queue
$ qpid-config add exchange topic my-topic
	</screen>
      
	<para>
        We can now use the address specified to drain to assert that it is
        of a particular type:
	</para>

	<screen>
$ ./drain 'my-queue; {assert: always, node:{ type: queue }}'
$ ./drain 'my-queue; {assert: always, node:{ type: topic }}'
2010-04-20 17:30:46 warning Exception received from broker: not-found: not-found: Exchange not found: my-queue (../../src/qpid/broker/ExchangeRegistry.cpp:92) [caused by 2 \x07:\x01]
Exchange my-queue does not exist
	</screen>

	<para>
        The first attempt passed without error as my-queue is indeed a
        queue. The second attempt however failed; my-queue is not a
        topic.
	</para>
      
	<para>
        We can do the same thing for my-topic:
	</para>

	<screen>
$ ./drain 'my-topic; {assert: always, node:{ type: topic }}'
$ ./drain 'my-topic; {assert: always, node:{ type: queue }}'
2010-04-20 17:31:01 warning Exception received from broker: not-found: not-found: Queue not found: my-topic (../../src/qpid/broker/SessionAdapter.cpp:754) [caused by 1 \x08:\x01]
Queue my-topic does not exist
	</screen>
      </example>

      <para>Now let's use the <literal>create</literal> option to
      create the queue <literal>xoxox</literal> if it does not already
      exist:</para>

      <example>
	<title>Creating a Queue Automatically</title>

	<para><emphasis>First Window:</emphasis></para>
	<screen>$ ./drain -t 30 "xoxox ; {create: always}"</screen>

	<para>In previous examples, we created the queue before
	listening for messages on it. Using <literal>create:
	always</literal>, the queue is automatically created if it
	does not exist. Now we can send messages to this queue:</para>

	<para><emphasis>Second Window:</emphasis></para>
	<screen>$ ./spout "xoxox ; {create: always}"</screen>
	
	<para>Returning to the first window, we see that <command>drain</command> has received this message:</para>

	<screen>Message(properties={spout-id:1a1a3842-1a8b-4f88-8940-b4096e615a7d:0}, content='')</screen>
      </example>

      <!--
         TODO: Add some x-declare, x-subscribe, link, x-bindings examples
        -->

      <para>Other options specify message transfer semantics; for
      instance, they may state whether messages should be consumed or
      read in browsing mode, or specify reliability
      characteristics. The following example uses the
      <literal>browse</literal> option to receive messages without
      removing them from a queue.</para>

      <example>
        <title>Browsing a Queue</title>
        <para>
          Let's use the browse mode to receive messages without
          removing them from the queue. First we send three messages to the
          queue:
        </para>
        <screen>
$ ./spout my-queue --content one
$ ./spout my-queue --content two
$ ./spout my-queue --content three
        </screen>
        
        <para>Now we use drain to get those messages, using the browse option:</para>
        <screen>
$ ./drain 'my-queue; {mode: browse}'
Message(properties={spout-id:fbb93f30-0e82-4b6d-8c1d-be60eb132530:0}, content='one')
Message(properties={spout-id:ab9e7c31-19b0-4455-8976-34abe83edc5f:0}, content='two')
Message(properties={spout-id:ea75d64d-ea37-47f9-96a9-d38e01c97925:0}, content='three')
        </screen>
        
        <para>We can confirm the messages are still on the queue by repeating the drain:</para>
        <screen>
$ ./drain 'my-queue; {mode: browse}'
Message(properties={spout-id:fbb93f30-0e82-4b6d-8c1d-be60eb132530:0}, content='one')
Message(properties={spout-id:ab9e7c31-19b0-4455-8976-34abe83edc5f:0}, content='two')
Message(properties={spout-id:ea75d64d-ea37-47f9-96a9-d38e01c97925:0}, content='three')
        </screen>
      </example>

      <!--
         TODO: Add some reliability option examples
        -->

      <table pgwide="1">
        <title>Address String Options</title>
        <tgroup cols="3">
          <thead>
	    <colspec colnum="1" colwidth="1*"/>
	    <colspec colnum="2" colwidth="3*"/>
	    <colspec colnum="3" colwidth="3*"/>
	    <row>
	      <entry>option</entry>
	      <entry>value</entry>
	      <entry>semantics</entry>
	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>
	        assert
	      </entry>
	      <entry>
	        one of: always, never, sender or receiver
	      </entry>
	      <entry>
	        Asserts that the properties specified in the node option
	        match whatever the address resolves to. If they do not,
	        resolution fails and an exception is raised. <!-- ###
	                                                          Which exception -->
	      </entry>
	    </row>

	    <row>
	      <entry>
	        create
	      </entry>
	      <entry>
                one of: always, never, sender or receiver
	      </entry>
	      <entry>
	        Creates the node to which an address refers if it does
	        not exist. No error is raised if the node does
	        exist. The details of the node may be specified in the
	        node option.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        delete
	      </entry>
	      <entry>
                one of: always, never, sender or receiver
	      </entry>
	      <entry>
	        Delete the node when the sender or receiver is closed.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        node
	      </entry>
	      <entry>
	        A nested map containing the entries shown in <xref linkend="table-node-properties"/>.
	      </entry>
	      <entry>
                Specifies properties of the node to which the address
                refers. These are used in conjunction with the assert or
                create options.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        link
	      </entry>
	      <entry>
	        A nested map containing the entries shown in <xref linkend="table-link-properties"/>.
	      </entry>
	      <entry>
                Used to control the establishment of a conceptual link
                from the client application to or from the target/source
                address.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        mode
	      </entry>
	      <entry>
	        one of: browse, consume
	      </entry>
	      <entry>
                This option is only of relevance for source addresses
                that resolve to a queue. If browse is specified the
                messages delivered to the receiver are left on the queue
                rather than being removed. If consume is specified the
                normal behaviour applies; messages are removed from teh
                queue once the client acknoweldges their receipt.
	      </entry>
	    </row>
          </tbody>
        </tgroup>
      </table>


      <table id="table-node-properties" pgwide="1">
        <title>Node Properties</title>
        <tgroup cols="3">
          <thead>
	    <colspec colnum="1" colwidth="1*"/>
	    <colspec colnum="2" colwidth="3*"/>
	    <colspec colnum="3" colwidth="3*"/>
	    <row>
	      <entry>property</entry>
	      <entry>value</entry>
	      <entry>semantics</entry>
	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>
	        type
	      </entry>
	      <entry>
	        topic, queue
	      </entry>
	      <entry>
	      </entry>
	    </row>
	    <row>
	      <entry>
	        durable
	      </entry>	       
	      <entry>
	        True, False
	      </entry>
	      <entry>
                Indicates whether the node survives a loss of
                volatile storage e.g. if the broker is restarted.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        x-declare
	      </entry>
	      <entry>
	        A nested map whose values correspond to the valid fields
	        on an AMQP 0-10 queue-declare or exchange-declare
	        command.
	      </entry>
	      <entry>
                These values are used to fine tune the creation or
                assertion process. Note however that they are protocol
                specific.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        x-bindings
	      </entry>
	      <entry>
	        A nested list in which each binding is represented by
	        a map. The entries of the map for a binding contain
	        the fields that describe an AMQP 0-10 binding. Here is
	        the format for x-bindings:

<programlisting><![CDATA[
[
 {
  exchange: <exchange>,
  queue: <queue>,
  key: <key>,
  arguments: { 
    <key_1>: <value_1>, 
    ..., 
    <key_n>: <value_n> }
 },
 ...
]
]]></programlisting>
	      </entry>
	      <entry>
                In conjunction with the create option, each of these
                bindings is established as the address is resolved. In
                conjunction with the assert option, the existence of
                each of these bindings is verified during
                resolution. Again, these are protocol specific.
	      </entry>
	    </row>
          </tbody>
        </tgroup>
      </table>

      <table id="table-link-properties" pgwide="1">
        <title>Link Properties</title>
        <tgroup cols="3">
          <thead>
	    <colspec colnum="1" colwidth="1*"/>
	    <colspec colnum="2" colwidth="3*"/>
	    <colspec colnum="3" colwidth="3*"/>
	    <row>
	      <entry>option</entry>
	      <entry>value</entry>
	      <entry>semantics</entry>
	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>
	        reliability
	      </entry>
	      <entry>
	        one of: unreliable, at-least-once, at-most-once, exactly-once
	      </entry>
	      <entry>
	      </entry>
	    </row>
	    <row>
	      <entry>
	        durable
	      </entry>	       
	      <entry>
	        True, False
	      </entry>
	      <entry>
                Indicates whether the link survives a loss of
                volatile storage e.g. if the broker is restarted.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        x-declare
	      </entry>
	      <entry>
	        A nested map whose values correspond to the valid fields
	        of an AMQP 0-10 queue-declare command.
	      </entry>
	      <entry>
                These values can be used to customise the subscription
	        queue in the case of receiving from an exchange. Note
	        however that they are protocol specific.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        x-subscribe
	      </entry>
	      <entry>
	        A nested map whose values correspond to the valid fields
	        of an AMQP 0-10 message-subscribe command.
	      </entry>
	      <entry>
                These values can be used to customise the subscription.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        x-bindings
	      </entry>
	      <entry>
	        A nested list each of whose entries is a map that may
	        contain fields (queue, exchange, key and arguments)
	        describing an AMQP 0-10 binding.
	      </entry>
	      <entry>
                These bindings are established during resolution
                independent of the create option. They are considered
                logically part of the linking process rather than of
                node creation.
	      </entry>
	    </row>
          </tbody>
        </tgroup>
      </table>

    </section>


  <section id="section-address-string-bnf">
    <title>Address String Grammar</title>

    <para>This section provides a formal grammar for address strings.</para>

    <formalpara>
      <title>Tokens</title>
      <para>The following regular expressions define the tokens used
      to parse address strings:</para></formalpara>
<programlisting><![CDATA[
LBRACE: \\{
RBRACE: \\}
LBRACK: \\[
RBRACK: \\]
COLON:  :
SEMI:   ;
SLASH:  /
COMMA:  ,
NUMBER: [+-]?[0-9]*\\.?[0-9]+
ID:     [a-zA-Z_](?:[a-zA-Z0-9_-]*[a-zA-Z0-9_])?
STRING: "(?:[^\\\\"]|\\\\.)*"|\'(?:[^\\\\\']|\\\\.)*\'
ESC:    \\\\[^ux]|\\\\x[0-9a-fA-F][0-9a-fA-F]|\\\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]
SYM:    [.#*%@$^!+-]
WSPACE: [ \\n\\r\\t]+
]]></programlisting>

    <formalpara>
      <title>Grammar</title>
      <para>The formal grammar for addresses is given below:</para>
    </formalpara>

    <programlisting><![CDATA[
address := name [ "/" subject ] [ ";" options ]
   name := ( part | quoted )+
subject := ( part | quoted | "/" )*
 quoted := STRING / ESC
   part := LBRACE / RBRACE / COLON / COMMA / NUMBER / ID / SYM
options := map
    map := "{" ( keyval ( "," keyval )* )? "}"
 keyval "= ID ":" value
  value := NUMBER / STRING / ID / map / list
   list := "[" ( value ( "," value )* )? "]"
   ]]></programlisting>


    <formalpara>
      <title>Address String Options</title>
      <para>The address string options map supports the following parameters:</para>
    </formalpara>

    <programlisting><![CDATA[
<name> [ / <subject> ] ; {
  create: always | sender | receiver | never,
  delete: always | sender | receiver | never,
  assert: always | sender | receiver | never,
  mode: browse | consume,
  node: {
    type: queue | topic,
    durable: True | False,
    x-declare: { ... <declare-overrides> ... },
    x-bindings: [<binding_1>, ... <binding_n>]
  },
  link: {
    name: <link-name>,
    durable: True | False,
    reliability: unreliable | at-most-once | at-least-once | exactly-once,
    x-declare: { ... <declare-overrides> ... },
    x-bindings: [<binding_1>, ... <binding_n>],
    x-subscribe: { ... <subscribe-overrides> ... }
  }
}
]]></programlisting>


    <itemizedlist>
      <title>Create, Delete, and Assert Policies</title>
      <para>The create, delete, and assert policies specify who should
      perfom the associated action:</para>
      <listitem><para><emphasis>always</emphasis>: the action is performed by any messaging client</para></listitem>
      <listitem><para><emphasis>sender</emphasis>: the action is only performed by a sender</para></listitem>
      <listitem><para><emphasis>receiver</emphasis>: the action is only performed by a receiver</para></listitem>
      <listitem><para><emphasis>never</emphasis>: the action is never performed (this is the default)</para></listitem>
    </itemizedlist>

    <itemizedlist>
      <title>Node-Type</title>
      <para>The node-type is one of:</para>
       <listitem><para><emphasis>topic</emphasis>: in the AMQP 0-10
       mapping, a topic node defaults to the topic exchange, x-declare
       may be used to specify other exchange types</para></listitem>
       <listitem><para><emphasis>queue</emphasis>: this is the default node-type</para></listitem>
    </itemizedlist>
  </section>


</section>

<section>
      <title>Logging</title>

      <section>
	<title>Logging in C++</title>
	<para>The Qpidd broker and C++ clients can both use environment
	variables to enable logging. Use QPID_LOG_ENABLE to set the
	level of logging you are interested in (trace, debug, info,
	notice, warning, error, or critical):</para>

<screen>
$ export QPID_LOG_ENABLE="warning+"
</screen>

      <para>The Qpidd broker and C++ clients use QPID_LOG_OUTPUT to
      determine where logging output should be sent. This is either a
      file name or the special values stderr, stdout, or syslog:</para>

<screen>
export QPID_LOG_TO_FILE="/tmp/myclient.out"
</screen>

      </section>
	
	<section>
		<title>Logging in Python</title>
		<para>
			The Python client library supports logging using the standard Python logging module. The easiest way to do logging is to use the <command>basicConfig()</command>, which reports all warnings and errors:
		</para>
		
<programlisting>from logging import basicConfig
basicConfig()
</programlisting>
		<para>
			Qpidd also provides a convenience method that makes it easy to specify the level of logging desired. For instance, the following code enables logging at the <command>DEBUG</command> level:
		</para>
		
<programlisting>from qpid.log import enable, DEBUG
enable("qpid.messaging.io", DEBUG)
</programlisting>
		<para>
			For more information on Python logging, see <ulink url="http://docs.python.org/lib/node425.html">http://docs.python.org/lib/node425.html</ulink>. For more information on Qpid logging, use <command>$ pydoc qpid.log</command>.
		</para>
	</section>
</section>

    
<section>
      <title>Reconnect and Failover</title>
      <para>Connections in the Qpid Messaging API support automatic
      reconnect if a connection is lost. This is done using connection
      options. The following example shows how to use connection options in C++ and Python.</para>

      <example>
	<title>Specifying Connection Options in C++ and Python</title>

	<para>In C++, these options are set using <function>Connection::setOption()</function>:</para>

      <programlisting><![CDATA[
Connection connection(broker);
connection.setOption("reconnect", true);
try {
    connection.open();
    !!! SNIP !!!
      ]]></programlisting>

	<para>In Python, these options are set using named arguments in
      the <function>Connection</function> constructor:</para>

      <programlisting><![CDATA[
connection = Connection("localhost:5672", reconnect=True)
try:
  connection.open()
  !!! SNIP !!!
      ]]></programlisting>

      <para>See the reference documentation for details on how to set
      these on connections for each language.</para>
      </example>

      <para>The following table lists the connection options that can
      be used.</para>

      <table pgwide="1">
        <title>Connection Options</title>
        <tgroup cols="3">
          <thead>
	    <colspec colnum="1" colwidth="1*"/>
	    <colspec colnum="2" colwidth="1*"/>
	    <colspec colnum="3" colwidth="3*"/>
	    <row>
	      <entry>option</entry>
	      <entry>value</entry>
	      <entry>semantics</entry>
	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>
	        reconnect
	      </entry>
	      <entry>
	        True, False
	      </entry>
	      <entry>
	        Transparently reconnect if the connection is lost.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        reconnect_timeout
	      </entry>
	      <entry>
	        N
	      </entry>
	      <entry>
	        Total number of seconds to continue reconnection attempts before giving up and raising an exception.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        reconnect_limit
	      </entry>
	      <entry>
	        N
	      </entry>
	      <entry>
	        Maximum number of reconnection attempts before giving up and raising an exception.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        reconnect_interval_min
	      </entry>
	      <entry>
	        N
	      </entry>
	      <entry>
	        Minimum number of seconds between reconnection attempts. The first reconnection attempt is made immediately; if that fails, the first reconnection delay is set to the value of <literal>reconnect_interval_min</literal>; if that attempt fails, the reconnect interval increases exponentially until a reconnection attempt succeeds or <literal>reconnect_interval_max</literal> is reached.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        reconnect_interval_max
	      </entry>
	      <entry>
	        N
	      </entry>
	      <entry>
	        Maximum reconnect interval.
	      </entry>
	    </row>
	    <row>
	      <entry>
	        reconnect_interval
	      </entry>
	      <entry>
	        N
	      </entry>
	      <entry>
	        Sets both <literal>reconnection_interval_min</literal> and <literal>reconnection_interval_max</literal> to the same value.
	      </entry>
	    </row>
          </tbody>
        </tgroup>
      </table>
    </section>

    <section>
      <title>Receiving Messages from Multiple Sources</title>

      <para>A receiver can only read from one source, but many
      programs need to be able to read messages from many sources,
      preserving the original sequence of the messages. In the Qpid
      Messaging API, a program can ask a session for the <quote>next
      receiver</quote>; that is, the receiver that is responsible for
      the next available message. The following example shows how this
      is done in C++ and Python.</para>

      <example>
	<title>Receiving Messages from Multiple Sources</title>

	<para>C++:</para>

	<programlisting><![CDATA[
Receiver receiver1 = session.createReceiver(address1);
Receiver receiver2 = session.createReceiver(address2);

Message message =  session.nextReceiver().fetch();
session.acknowledge(); // acknowledge message receipt
std::cout << message.getContent() << std::endl;
]]>	  </programlisting>

	<para>Python:</para>
	<programlisting><![CDATA[
receiver1 = session.receiver(address1)
receiver2 = session.receiver(address)
message = session.next_receiver().fetch()
print message.content
]]>	  </programlisting>
      </example>
    </section>

    <section>
      <title>Request / Response</title>
      <para>Request / Response applications use the reply-to property,
      described in <xref
      linkend="table-amqp0-10-message-properties"/>, to allow a server
      to respond to the client that sent a message. A server sets up a
      service queue, with a name known to clients. A client creates a
      private queue for the server's response, creates a message for a
      request, sets the request's reply-to property to the address of
      the client's response queue, and sends the request to the
      service queue. The server sends the response to the address
      specified in the request's reply-to property.
      </para>
      <example>
	<title>Request / Response Applications in C++</title>

	<para>This example shows the C++ code for a client and server
	that use the request / response pattern.</para>

	<para>The server creates a service queue and waits for a
	message to arrive. If it receives a message, it sends a
	message back to the sender.</para>

	<programlisting><![CDATA[Receiver receiver = session.createReceiver("service_queue; {create: always}");

Message request = receiver.fetch();
const Address&amp; address = request.getReplyTo(); // Get "reply-to" from request ...
if (address) {
  Sender sender = session.createSender(address); // ... send response to "reply-to"
  Message response("pong!");
  sender.send(response);
  session.acknowledge();
}
     ]]></programlisting>

	<para>The client creates a sender for the service queue, and
	also creates a response queue that is deleted when the
	client closes the receiver for the response queue. In the C++
	client, if the address starts with the character
	<literal>#</literal>, it is given a unique name.</para>

	<programlisting><![CDATA[
Sender sender = session.createSender("service_queue");

Address responseQueue("#response-queue; {create:always, delete:always}");
Receiver receiver = session.createReceiver(responseQueue);

Message request;
request.setReplyTo(responseQueue);
request.setContent("ping");
sender.send(request);
Message response = receiver.fetch();
std::cout << request.getContent() << " -> " << response.getContent() << std::endl;
]]>	  </programlisting>

	<para>The client sends the string <literal>ping</literal> to
	the server. The server sends the response
	<literal>pong</literal> back to the same client, using the
	<varname>replyTo</varname> property.</para>

      </example>
<!--
      <example>
	<title>Request / Response Applications in Python</title>
	<programlisting>### TODO</programlisting>
      </example>
-->
    </section>
    <section id="section-Maps">
      <title>Maps in Message Content</title>
      
      <para>Many messaging applications need to exchange data across
      languages and platforms, using the native datatypes of each
      programming language. AMQP provides a set of portable datatypes,
      but does not directly support a set of named type/value
      pairs. Java JMS provides the <classname>MapMessage</classname>
      interface, which allows sets of named type/value pairs, but does
      not provide a set of portable datatypes.</para> 

      <para>The Qpid Messaging API supports maps in message
      content. Unlike JMS, any message can contain maps. These maps
      are supported in each language using the conventions of the
      language. In Java, we implement the
      <classname>MapMessage</classname> interface; in Python, we
      support <classname>dict</classname> and
      <classname>list</classname> in message content; in C++, we
      provide the <classname>Variant::Map</classname> and
      <classname>Variant::List</classname> classes to represent maps
      and lists. In all languages, messages are encoded using AMQP's
      portable datatypes.
      </para>

      <tip>
      <para>Because of the differences in type systems among
      languages, the simplest way to provide portable messages is to
      rely on maps, lists, strings, 64 bit signed integers, and
      doubles for messages that need to be exchanged across languages
      and platforms.</para>
      </tip>

      <section id="section-Python-Maps">
	<title>Qpid Maps in Python</title>

	<para>In Python, Qpid supports the <classname>dict</classname> and <classname>list</classname> types directly in message content. The following code shows how to send these structures in a message:</para>

	<example>
	  <title>Sending Qpid Maps in Python</title>
	  <programlisting><![CDATA[
from qpid.messaging import *
# !!! SNIP !!!

content = {'Id' : 987654321, 'name' : 'Widget', 'percent' : 0.99}
content['colours'] = ['red', 'green', 'white']
content['dimensions'] = {'length' : 10.2, 'width' : 5.1,'depth' : 2.0};
content['parts'] = [ [1,2,5], [8,2,5] ]
content['specs'] = {'colors' : content['colours'], 
                    'dimensions' : content['dimensions'], 
                    'parts' : content['parts'] }
message = Message(content=content)
sender.send(message)
    ]]>   </programlisting>
	</example>


      <para>The following table shows the datatypes that can be sent in a Python map message,
 and the corresponding datatypes that will be received by clients in Java or C++.</para>
      

	<table id="table-Python-Maps" >
	<title>Python Datatypes in Maps</title>
	<tgroup cols="3">
	  <thead>
	    <row>
	      <entry>Python Datatype</entry>
	      <entry>&rarr; C++</entry>
	      <entry>&rarr; Java</entry>
	    </row>
	  </thead>
	  <tbody>
   	    <row><entry>bool</entry><entry>bool</entry><entry>boolean</entry></row>
	    <row><entry>integer</entry><entry>long</entry><entry>long</entry></row>
	    <row><entry>long</entry><entry>long</entry><entry>long</entry></row>
	    <row><entry>float</entry><entry>double</entry><entry>double</entry></row>
	    <row><entry>unicode</entry><entry>string</entry><entry>java.lang.String</entry></row>
	    <row><entry>uuid</entry><entry>qpid::types::Uuid</entry><entry>java.util.UUID</entry></row>
	    <row><entry>dict</entry><entry>Variant::Map</entry><entry>java.util.Map</entry></row>
	    <row><entry>list</entry><entry>Variant::List</entry><entry>java.util.List</entry></row>
	  </tbody>
	</tgroup>
      </table>

      </section>




      <section id="section-cpp-Maps">
	<title>Qpid Maps in C++</title>


	<para>In C++, Qpid defines the the
	<classname>Variant::Map</classname> and
	<classname>Variant::List</classname> types, which can be
	encoded into message content. The following code shows how to
	send these structures in a message:</para>

	<example>
	  <title>Sending Qpid Maps in C++</title>
	<programlisting><![CDATA[
using namespace qpid::types;

// !!! SNIP !!!

Message message;
Variant::Map content;
content["id"] = 987654321;
content["name"] = "Widget";
content["percent"] = 0.99;
Variant::List colours;
colours.push_back(Variant("red"));
colours.push_back(Variant("green"));
colours.push_back(Variant("white"));
content["colours"] = colours;

Variant::Map dimensions;
dimensions["length"] = 10.2;
dimensions["width"] = 5.1;
dimensions["depth"] = 2.0;
content["dimensions"]= dimensions; 

Variant::List part1;
part1.push_back(Variant(1));
part1.push_back(Variant(2));
part1.push_back(Variant(5));
 
Variant::List part2;
part2.push_back(Variant(8));
part2.push_back(Variant(2));
part2.push_back(Variant(5));
 
Variant::List parts;
parts.push_back(part1);
parts.push_back(part2);
content["parts"]= parts; 

Variant::Map specs;
specs["colours"] = colours; 
specs["dimensions"] = dimensions; 
specs["parts"] = parts; 
content["specs"] = specs;

encode(content, message);
sender.send(message, true);
]]>     </programlisting>
	</example>

	<para>The following table shows the datatypes that can be sent
	in a C++ map message, and the corresponding datatypes that
	will be received by clients in Java and Python.</para>
      
	<table  id="table-cpp-Maps">
	<title>C++ Datatypes in Maps</title>
	<tgroup cols="3">
	  <thead>
	    <row>
	      <entry>C++ Datatype</entry>
	      <entry>&rarr; Python</entry>
	      <entry>&rarr; Java</entry>
	    </row>
	  </thead>
	  <tbody>
   	    <row><entry>bool</entry><entry>bool</entry><entry>boolean</entry></row>
  	    <row><entry>unsigned char</entry><entry>unicode</entry><entry>char</entry></row>
	    <row><entry>unsigned short int</entry><entry>integer | long</entry><entry>short</entry></row>
	    <row><entry>unsigned int</entry><entry>integer | long</entry><entry>integer</entry></row>
	    <row><entry>unsigned long</entry><entry>integer | long</entry><entry>long</entry></row>
	    <row><entry>char</entry><entry>unicode</entry><entry>char</entry></row>
	    <row><entry>short</entry><entry>integer | long</entry><entry>short</entry></row>
	    <row><entry>int</entry><entry>integer | long</entry><entry>integer</entry></row>
	    <row><entry>long</entry><entry>integer | long</entry><entry>long</entry></row>
	    <row><entry>float</entry><entry>float</entry><entry>float</entry></row>
	    <row><entry>double</entry><entry>float</entry><entry>double</entry></row>
	    <row><entry>string</entry><entry>unicode</entry><entry>java.lang.String</entry></row>
	    <row><entry>qpid::types::Uuid</entry><entry>uuid</entry><entry>java.util.UUID</entry></row>
	    <row><entry>Variant::Map</entry><entry>dict</entry><entry>java.util.Map</entry></row>
	    <row><entry>Variant::List</entry><entry>list</entry><entry>java.util.List</entry></row>
	  </tbody>
	</tgroup>
      </table>
      </section>

      
</section> 
        <section>
      <title>Performance</title>
      <para>
         Clients can often be made significantly faster by batching acknowledgements and setting the capacity of receivers to allow prefetch. 	
      </para>
      <section>
	<title>Batching Acknowledgements</title>

	<para>Many of the simple examples we have shown retrieve a message and immediately acknowledge it. Because each acknowledgement results in network traffic, you can dramatically increase performance by acknowledging messages in batches. For instance, an application can read a number of related messages, then acknowledge the entire batch, or an application can acknowledge after a certain number of messages have been received or a certain time period has elapsed. Messages are not removed from the broker until they are acknowledged, so guaranteed delivery is still available when batching acknowledgements.</para>
      </section>


      <section>
	<title>Prefetch</title>   

	<para>By default, a receiver retrieves the next message from the server, one message at a time, which provides intuitive results when writing and debugging programs, but does not provide optimum performance. To create an input buffer, set the capacity of the receiver to the size of the desired input buffer; for many applications, a capacity of 100 performs well. </para>

<!--
###	sender: capacity of replay buffer (not yet acknowledged messages), these are resent with failover
-->

	<example>
	  <title>Prefetch</title>
	  
	  <para>C++</para>
	  <programlisting>
Receiver receiver = session.createReceiver(address);
receiver.setCapacity(100);
Message message = receiver.fetch();
	  </programlisting>
<!--
	  <para>Python</para>
	  <programlisting>
	  </programlisting>
-->
  
	</example>
      </section>

    </section>

    <section>
      <title>Reliability</title>

      <section>
	<title>Guaranteed Delivery</title>

	<para>If a queue is durable, the queue survives a messaging
	broker crash, as well as any durable messages that have been
	placed on the queue. These messages will be delivered when the
	messaging broker is restarted. Delivery is guaranteed if and
	only if both the message and the queue are durable. Guaranteed
	delivery requires a persistence module, such as the one
	available from <ulink
	url="http://QpidComponents.org">QpidComponents.org</ulink>.</para>

	<example>
	  <title>Guaranteed Delivery</title>

	  <para>C++:</para>

	  <programlisting><![CDATA[
Sender sender = session.createSender("durable-queue");

Message message("Hello world!");
message.setDurable(1);

sender.send(Message("Hello world!"));
]]></programlisting>
	</example>
<!--
	  <para>Python:</para>
-->
<!--	</example>

	<section>
	  <title>Cluster Failover </title>
	</section>
-->

      </section>

    </section>

<!--
    <section>
      <title>Security</title>
##########
    </section>
-->

    <section>
      <title>Transactions</title>
      <para>In AMQP, transactions cover the semantics of enqueues and
      dequeues.</para>

      <para>When sending messages, a transaction tracks enqueues
      without actually delivering the messages, a commit places
      messages on their queues, and a rollback discards the
      enqueues.</para>

      <para>When receiving messages, a transaction tracks dequeues
      without actually removing acknowledged messages, a commit
      removes all acknowledged messages, and a rollback discards
      acknowledgements. A rollback does not release the message, it
      must be explicitly released to return it to the queue.</para>

      <example>
	<title>Transactions</title>
	<para>C++:</para>
	<programlisting><![CDATA[
Connection connection(broker);
Session session =  connection.createTransactionalSession();
...
if (smellsOk())
   session.commit();
else 
   session.rollback();
   ]]></programlisting>
<!--
	<para>Python</para>
	<programlisting><![CDATA[
### TODO
   ]]></programlisting>
-->
      </example>

    </section>





  <section>
      <title>XML Exchange</title>

      <para>The XML Exchange is an AMQP 0-10 custom exchange provided by the Apache Qpid C++ broker. It allows messages to be filtered using XQuery; queries can address either message properties or XML content in the body of the message.</para>

      <para>An instance of the XML Exchange must be added before it can be used:</para>

      <programlisting>
$ qpid-config add exchange xml xml
      </programlisting>

      <para>When using the XML exchange, a sender's address string must provide a subject, e.g. <literal>xml/weather</literal>.</para>

      <para>If a receiver that is using the XML exchange also provides a subject, it receives messages if the subject exactly matches a message's subject.</para>


      <para>When using the XML Exchange, a receiver normally provides an XQuery as an x-binding argument. If the query contains a context item (a path starting with <quote>.</quote>), then it is applied to the content of the message, which must be well-formed XML. For instance, <literal>./weather</literal> is a valid XQuery, which matches any message in which the root element is named <literal>weather</literal>. Here is an address string that contains this query:</para>

      <programlisting><![CDATA[
xml; {
 link: { 
  x-bindings: [{ exchange:xml, key:weather, arguments:{xquery:"./weather"} }] 
 } 
}
  ]]></programlisting>

      <para>Note that each x-binding is created in addition to any other bindings that may exist, and each x-binding must include the exchange name, the key, and the xquery. If you specify the subject in the address string (e.g. <literal>xml/weather; link ...</literal>), it creates a binding that is used in addition to the x-bindings; the binding created for the subject matches any message whose subject is <literal>weather</literal>, the binding created for the x-binding matches any message that satisfies the query, i.e. any message with a root element named <literal>weather</literal>.
      </para>


      <para>The XML Exchange can also be used to query message properties by declaring an external variable with the same name as each property that is to be queried. The following XQuery queries the <literal>control</literal> property, as well as the content of the message:</para>

      <programlisting><![CDATA[
declare variable $control external;
./message/id mod 2 = 1 or $control = 'end'
]]></programlisting>

      <para>If the XQuery addresses message content, and the message is not well-formed XML, the message will not be received. If the XQuery does not query message content, the message need not contain XML.</para>


      <example>
	<title>Using the XML Exchange with <command>drain</command></title>

	<para>The following shows the arguments used with <command>drain</command> to retrieve messages whose root element is named <literal>weather</literal>:</para>

	<programlisting><![CDATA[
$ ./drain -f "xml; {link:{x-bindings: [{exchange: xml, key:"weather", 
arguments:{xquery:\"./weather\"}}]}}"
 ]]></programlisting> 
      </example>

      <example>
	<title>Using the XML Exchange with C++</title>

	<para>In C++, it is convenient to place an XQuery in a string, and use a <classname>stringstream</classname> to add the query to the template for an address string that specifies an x-binding.</para>

	<programlisting><![CDATA[
std::string query = 
  "let $w := ./weather "
  "return $w/station = 'Raleigh-Durham International Airport (KRDU)' "
  "   and $w/temperature_f > 50"
  "   and $w/temperature_f - $w/dewpoint > 5"
  "   and $w/wind_speed_mph > 7"
  "   and $w/wind_speed_mph < 20";

stringstream address;

address << "xml; {"
  " link: { "
  "  x-bindings: [{ exchange: xml, key: weather, arguments: { xquery:\"" 
     << query 
     << "\"} }] "
  " } "
  "}";


Receiver receiver = session.createReceiver(address.str());
Message response = receiver.fetch();
session.acknowledge();
std::cout << response.getContent() << std::endl;

      ]]></programlisting>
      </example>


      <example>
	<title>Using the XML Exchange with Python</title>

	<para>In Python, it is often convenient to place the query in
	a separate string, and use the repr() value of the query
	string in an address template string.</para>

	<programlisting><![CDATA[
# Set up the receiver
  query = """
   let $w := ./weather
   return $w/station = 'Raleigh-Durham International Airport (KRDU)'
      and $w/temperature_f > 50
      and $w/temperature_f - $w/dewpoint > 5
      and $w/wind_speed_mph > 7
      and $w/wind_speed_mph < 20   """

  address = """
    xml; {
       link: { 
         x-bindings: [{ exchange: xml, key: weather, arguments: { xquery: %r} }] 
       } 
    }
    """ % query

  receiver = session.receiver(address)

# Retrieve matching message from the receiver and print it

  message = receiver.fetch(timeout=1)
  print message.content
  session.acknowledge()
	]]></programlisting>
      </example>

    </section>

<section id="section-amqp0-10-mapping">
    <title>The AMQP 0-10 mapping</title>

    <para>
      This section describes the AMQP 0-10 mapping for the Qpid
      Messaging API.
    </para>
    <para>
        The interaction with the broker triggered by creating a sender
        or receiver depends on what the specified address resolves
        to. Where the node type is not specified in the address, the
        client queries the broker to determine whether it refers to a
        queue or an exchange.
    </para>
    <para>
        When sending to a queue, the queue's name is set as the
        routing key and the message is transfered to the default (or
        nameless) exchange. When sending to an exchange, the message
        is transfered to that exchange and the routing key is set to
        the message subject if one is specified. A default subject may
        be specified in the target address. The subject may also be
        set on each message individually to override the default if
        required. In each case any specified subject is also added as
        a qpid.subject entry in the application-headers field of the
        message-properties.
      </para>
      <para>
        When receiving from a queue, any subject in the source address
        is currently ignored. The client sends a message-subscribe
        request for the queue in question. The accept-mode is
        determined by the reliability option in the link properties;
        for unreliable links the accept-mode is none, for reliable
        links it is explicit. The default for a queue is reliable. The
        acquire-mode is determined by the value of the mode option. If
        the mode is set to browse the acquire mode is not-acquired,
        otherwise it is set to pre-acquired. The exclusive and
        arguments fields in the message-subscribe command can be
        controlled using the x-subscribe map.
      </para>
      <para>
        When receiving from an exchange, the client creates a
        subscription queue and binds that to the exchange. The
        subscription queue's arguments can be specified using the
        x-declare map within the link properties. The reliability
        option determines most of the other parameters. If the
        reliability is set to unreliable then an auto-deleted,
        exclusive queue is used meaning that if the client or
        connection fails messages may be lost. For exactly-once the
        queue is not set to be auto-deleted. The durability of the
        subscription queue is determined by the durable option in the
        link properties. The binding process depends on the type of
        the exchange the source address resolves to.
      </para>

      <itemizedlist>
        <listitem>
          <para>
            For a topic exchange, if no subject is specified and no
            x-bindings are defined for the link, the subscription
            queue is bound using a wildcard matching any routing key
            (thus satisfying the expectation that any message sent to
            that address will be received from it). If a subject is
            specified in the source address however, it is used for
            the binding key (this means that the subject in the source
            address may be a binding pattern including wildcards).
          </para>
        </listitem>
        <listitem>
          <para>
            For a fanout exchange the binding key is irrelevant to
            matching. A receiver created from a source address that
            resolves to a fanout exchange receives all messages
            sent to that exchange regardless of any subject the source
            address may contain. An x-bindings element in the link
            properties should be used if there is any need to set the
            arguments to the bind.
          </para>
        </listitem>
        <listitem>
          <para>
            For a direct exchange, the subject is used as the binding
            key. If no subject is specified an empty string is used as
            the binding key.
          </para>
        </listitem>
        <listitem>
          <para>
            For a headers exchange, if no subject is specified the
            binding arguments simply contain an x-match entry and no
            other entries, causing all messages to match. If a subject
            is specified then the binding arguments contain an x-match
            entry set to all and an entry for qpid.subject whose value
            is the subject in the source address (this means the
            subject in the source address must match the message
            subject exactly). For more control the x-bindings element
            in the link properties must be used.
          </para>
        </listitem>
        <listitem>
          <para>
            For the XML exchange,<footnote><para>Note that the XML
            exchange is not a standard AMQP exchange type. It is a
            Qpid extension and is currently only supported by the C++
            broker.</para></footnote> if a subject is specified it is
            used as the binding key and an XQuery is defined that
            matches any message with that value for
            qpid.subject. Again this means that only messages whose
            subject exactly match that specified in the source address
            are received. If no subject is specified then the empty
            string is used as the binding key with an xquery that will
            match any message (this means that only messages with an
            empty string as the routing key will be received). For more
            control the x-bindings element in the link properties must
            be used. A source address that resolves to the XML
            exchange must contain either a subject or an x-bindings
            element in the link properties as there is no way at
            present to receive any message regardless of routing key.
          </para>
        </listitem>
      </itemizedlist>

      <para>
        If an x-bindings list is present in the link options a binding
        is created for each element within that list. Each element is
        a nested map that may contain values named queue, exchange,
        key or arguments. If the queue value is absent the queue name
        the address resolves to is implied. If the exchange value is
        absent the exchange name the address resolves to is implied.
      </para>

      <para>The following table shows how Qpid Messaging API message
        properties are mapped to AMQP 0-10 message properties and
        delivery properties. In this table <varname>msg</varname>
        refers to the Message class defined in the Qpid Messaging API,
        <varname>mp</varname> refers to an AMQP 0-10
        <varname>message-properties</varname> struct, and
        <varname>dp</varname> refers to an AMQP 0-10
        <varname>delivery-properties</varname> struct.</para>

      <table id="table-amqp0-10-message-properties" pgwide="1">
        <title>Mapping to AMQP 0-10 Message Properties</title>
        <tgroup cols="3">
          <thead>
	    <colspec colnum="1" colname="Python API" colwidth="3*"/>
	    <colspec colnum="2" colname="C++ API" colwidth="3*"/>
	    <colspec colnum="3" colname="AMPQ 0-10 Property" colwidth="6*"/>
	    <row>
	      <entry>Python API</entry>
	      <entry>C++ API</entry>
	      <entry>AMQP 0-10 Property<footnote><para>In these entries, <literal>mp</literal> refers to an AMQP message property, and <literal>dp</literal> refers to an AMQP delivery property.</para></footnote></entry>
	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>msg.id</entry><entry>msg.{get,set}MessageId()</entry><entry>mp.message_id</entry>
	    </row>
	    <row>
	      <entry>msg.subject</entry><entry>msg.{get,set}Subject()</entry><entry>mp.application_headers["qpid.subject"]</entry>
	    </row>
	    <row>
	      <entry>msg.user_id</entry><entry>msg.{get,set}UserId()</entry><entry>mp.user_id</entry>
	    </row>
	    <row>
	      <entry>msg.reply_to</entry><entry>msg.{get,set}ReplyTo()</entry><entry>mp.reply_to<footnote><para>The reply_to is converted from the protocol representation into an address.</para></footnote></entry>
	    </row>
	    <row>
	      <entry>msg.correlation_id</entry><entry>msg.{get,set}CorrelationId()</entry><entry>mp.correlation_id</entry>
	    </row>
	    <row>
	      <entry>msg.durable</entry><entry>msg.{get,set}Durable()</entry><entry>dp.delivery_mode == delivery_mode.persistent<footnote><para>Note that msg.durable is a boolean, not an enum.</para></footnote></entry>
	    </row>
	    <row>
	      <entry>msg.priority</entry><entry>msg.{get,set}Priority()</entry><entry>dp.priority</entry>
	    </row>
	    <row>
	      <entry>msg.ttl</entry><entry>msg.{get,set}Ttl()</entry><entry>dp.ttl</entry>
	    </row>
	    <row>
	      <entry>msg.redelivered</entry><entry>msg.{get,set}Redelivered()</entry><entry>dp.redelivered</entry>
	    </row>
	    <row><entry>msg.properties</entry><entry>msg.{get,set}Properties()</entry><entry>mp.application_headers</entry>
	    </row>
	    <row>
	      <entry>msg.content_type</entry><entry>msg.{get,set}ContentType()</entry><entry>mp.content_type</entry>
	    </row>
          </tbody>
        </tgroup>
      </table>
      
    </section>
  </chapter>


  <chapter id="QpidJMS">
    <title>Using the Qpid JMS client</title>
    <section>
      <title>A Simple Messaging Program in Java JMS</title>
      
      <para>The following program shows how to use address strings and
      JNDI for Qpid programs that use Java JMS.</para>

      <para>The Qpid JMS client uses Qpid Messaging API <xref
      linkend="section-addresses"/> to identify sources and
      targets. This program uses a JNDI file that defines a connection
      factory for the broker we are using, and the address of the
      topic exchange node that we bind the sender and receiver
      to. (The syntax of a ConnectionURL is given in <xref
      linkend="QpidJNDI"/>.)</para>

      <example>
	<title>JNDI Properties File for "Hello world!" example</title>
      <programlisting><![CDATA[
java.naming.factory.initial 
  = org.apache.qpid.jndi.PropertiesFileInitialContextFactory

# connectionfactory.[jndiname] = [ConnectionURL]
connectionfactory.qpidConnectionfactory 
  = amqp://guest:guest@clientid/test?brokerlist='tcp://localhost:5672'
# destination.[jndiname] = [address_string]
destination.topicExchange = amq.topic
]]></programlisting>
      </example>

      <para>In the Java JMS code, we use create a JNDI context, use the context to find a connection factory and create and start a connection, create a session, and create a destination that corresponds to the topic exchange. Then we create a sender and a receiver, send a message with the sender, and receive it with the receiver. This code should be straightforward for anyone familiar with Java JMS.</para>

      <example>
	<title>"Hello world!" in Java</title>
	<programlisting lang="java"><![CDATA[
package org.apache.qpid.example.jmsexample.hello;

import javax.jms.*;
import javax.naming.Context;
import javax.naming.InitialContext;
import java.util.Properties;

public class Hello {

  public Hello() {
  }

  public static void main(String[] args) {
    Hello producer = new Hello();
    producer.runTest();
  }

  private void runTest() {
    try {
      Properties properties = new Properties();
      properties.load(this.getClass().getResourceAsStream("hello.properties"));
      Context context = new InitialContext(properties);

      ConnectionFactory connectionFactory 
                    = (ConnectionFactory) context.lookup("qpidConnectionfactory");
      Connection connection = connectionFactory.createConnection();
      connection.start();

      Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
      Destination destination = (Destination) context.lookup("topicExchange");

      MessageProducer messageProducer = session.createProducer(destination);
      MessageConsumer messageConsumer = session.createConsumer(destination);

      TextMessage message = session.createTextMessage("Hello world!");
      messageProducer.send(message);

      message = (TextMessage)messageConsumer.receive();
      System.out.println(message.getText());

      connection.close();
      context.close();
    }
    catch (Exception exp) {
      exp.printStackTrace();
    }
  }
}
]]></programlisting>
      </example>

    </section>

    <section id="QpidJNDI">
      <title>Apache Qpid JNDI Properties for AMQP Messaging</title>


      <para>
	Apache Qpid defines JNDI properties that can be used to specify JMS Connections and Destinations. Here is a typical JNDI properties file:
      </para>

      <example>
	<title>JNDI Properties File</title>
    <programlisting><![CDATA[
java.naming.factory.initial 
  = org.apache.qpid.jndi.PropertiesFileInitialContextFactory

# connectionfactory.[jndiname] = [ConnectionURL]
connectionfactory.qpidConnectionfactory 
  = amqp://guest:guest@clientid/test?brokerlist='tcp://localhost:5672'
# destination.[jndiname] = [address_string]
destination.topicExchange = amq.topic
]]></programlisting>
      </example>

      <para>The following sections describe the JNDI properties that Qpid uses.</para>

      
      <section>
        <title>JNDI Properties for Apache Qpid</title>
        <para>
	  Apache Qpid supports the properties shown in the following table:
        </para>
        <table>
	  <title>JNDI Properties supported by Apache Qpid</title>
	  <tgroup cols="2">
	    <thead>
	      <row>
	        <entry>
		  Property
	        </entry>
	        <entry>
		  Purpose
	        </entry>
	      </row>
	    </thead>
	    <tbody>
	      <row>
	        <entry>
		  connectionfactory.&lt;jndiname&gt;
	        </entry>
	        <entry>
		  <para>
		    The Connection URL that the connection factory uses to perform connections.
		  </para>
	        </entry>
	      </row>
	      <row>
	        <entry>
		  queue.&lt;jndiname&gt;
	        </entry>
	        <entry>
		  <para>
		    A JMS queue, which is implemented as an amq.direct exchange in Apache Qpid.
		  </para>
	        </entry>
	      </row>
	      <row>
	        <entry>
		  topic.&lt;jndiname&gt;
	        </entry>
	        <entry>
		  <para>
		    A JMS topic, which is implemented as an amq.topic exchange in Apache Qpid.
		  </para>
	        </entry>
	      </row>
	      <row>
	        <entry>
		  destination.&lt;jndiname&gt;
	        </entry>
	        <entry>
		  <para>
		    Can be used for defining all amq destinations,
		    queues, topics and header matching, using an
		    address string.  

		    <footnote><para>Binding URLs, which were used in
		    earlier versions of the Qpid Java JMS client, can
		    still be used instead of address
		    strings.</para></footnote>
		  </para>
	        </entry>
	      </row>
	    </tbody>
	  </tgroup>
        </table>
      </section>
      
      <section>
        <title>Connection URLs</title>
        <para>
	  In JNDI properties, a Connection URL specifies properties for a connection. The format for a Connection URL is:
        </para>
        
        <programlisting>amqp://[&lt;user&gt;:&lt;pass&gt;@][&lt;clientid&gt;]&lt;virtualhost&gt;[?&lt;option&gt;=&#39;&lt;value&gt;&#39;[&amp;&lt;option&gt;=&#39;&lt;value&gt;&#39;]]
        </programlisting>
        <para>
	  For instance, the following Connection URL specifies a user name, a password, a client ID, a virtual host ("test"), a broker list with a single broker, and a TCP host with the host name <quote>localhost</quote> using port 5672:
        </para>
        
        <programlisting>amqp://username:password@clientid/test?brokerlist=&#39;tcp://localhost:5672&#39;
        </programlisting>
        <para>
	  Apache Qpid supports the following properties in Connection URLs:
        </para>
        <table pgwide="1">
	  <title>Connection URL Properties</title>
	  <tgroup cols="3">
	    <thead>
	      <row>
	        <entry>
		  Option
	        </entry>
	        <entry>
		  Type
	        </entry>
	        <entry>
		  Description
	        </entry>
	      </row>
	    </thead>
	    <tbody>
	      <row>
	        <entry>
		  brokerlist
	        </entry>
	        <entry>
		  see below
	        </entry>
	        <entry>
		  The broker to use for this connection. In the current release, precisely one broker must be specified.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  maxprefetch
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  The maximum number of pre-fetched messages per destination.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sync_publish
	        </entry>
	        <entry>
           {'persistent' | 'all'}
	        </entry>
	        <entry>
          A sync command is sent after every persistent message to guarantee that it has been received; if the value is 'persistent', this is done only for persistent messages.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sync_ack
	        </entry>
	        <entry>
           Boolean
	        </entry>
	        <entry>
          A sync command is sent after every acknowledgement to guarantee that it has been received.
	        </entry>
	      </row>
          <row>
	        <entry>
		  use_legacy_map_msg_format
	        </entry>
	        <entry>
          Boolean
	        </entry>
	        <entry>
          If you are using JMS Map messages and deploying a new client with any JMS client older than 0.7 release, you must set this to true to ensure the older clients can understand the map message encoding.
	        </entry>
	      </row>
          <row>
	        <entry>
		  failover
	        </entry>
	        <entry>
           {'roundrobin' | 'failover_exchange'}
	        </entry>
	        <entry>
          If roundrobin is selected it will try each broker given in the broker list.
          If failover_exchange is selected it connects to the initial broker given in the broker URL and will receive membership updates via the failover exchange.
	        </entry>
	      </row>
	    </tbody>
	  </tgroup>
        </table>
        <para>
	  Broker lists are specified using a URL in this format:
        </para>
        
        <programlisting>brokerlist=&lt;transport&gt;://&lt;host&gt;[:&lt;port&gt;](?&lt;param>=&lt;value>)?(&amp;&lt;param>=&lt;value>)*</programlisting>
        <para>
	  For instance, this is a typical broker list:
        </para>
        
        <programlisting>brokerlist=&#39;tcp://localhost:5672&#39;
        </programlisting>

	<para>
	  A broker list can contain more than one broker address; if so, the connection is made to the first broker in the list that is available. In general, it is better to use the failover exchange when using multiple brokers, since it allows applications to fail over if a broker goes down.
	</para>

	<example>
	  <title>Broker Lists</title>
	<para>A broker list can specify properties to be used when connecting to the broker, such as security options. This broker list specifies options for a Kerberos connection using GSSAPI:</para>
	<programlisting><![CDATA[
amqp://guest:guest@test/test?sync_ack='true'
    &brokerlist='tcp://ip1:5672?sasl_mechs='GSSAPI'
	]]></programlisting>

	<para>This broker list specifies SSL options:</para>

	<programlisting><![CDATA[
amqp://guest:guest@test/test?sync_ack='true'
   &brokerlist='tcp://ip1:5672?ssl='true'&ssl_cert_alias='cert1'
	]]></programlisting>
	</example>

	<para>The following broker list options are supported.</para>

        <table pgwide="1">
	  <title>Broker List Options</title>
	  <tgroup cols="3">
	    <thead>
	      <row>
	        <entry>
		  Option
	        </entry>
	        <entry>
		  Type
	        </entry>
	        <entry>
		  Description
	        </entry>
	      </row>
	    </thead>
	    <tbody>
	      <row>
	        <entry>
		  heartbeat
	        </entry>
	        <entry>
		  integer
	        </entry>
	        <entry>
		  frequency of heartbeat messages (in seconds)
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sasl_mechs
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  For secure applications, we suggest CRAM-MD5,
		  DIGEST-MD5, or GSSAPI. The ANONYMOUS method is not
		  secure. The PLAIN method is secure only when used
		  together with SSL. For Kerberos, sasl_mechs must be
		  set to GSSAPI, sasl_protocol must be set to the
		  principal for the qpidd broker, e.g. qpidd/, and
		  sasl_server must be set to the host for the SASL
		  server, e.g. sasl.com.  SASL External is supported
		  using SSL certification, e.g.
		  <literal>ssl='true'&amp;sasl_mechs='EXTERNAL'</literal>
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sasl_encryption
	        </entry>
	        <entry>
          Boolean  
	        </entry>
	        <entry>
          If <literal>sasl_encryption='true'</literal>, the JMS client attempts to negotiate a security layer with the broker using GSSAPI to encrypt the connection. Note that for this to happen, GSSAPI must be selected as the sasl_mech.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  ssl
	        </entry>
	        <entry>
		  Boolean
	        </entry>
	        <entry>
		  If <literal>ssl='true'</literal>, the JMS client will encrypt the connection using SSL.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  tcp_nodelay
	        </entry>
	        <entry>
		  Boolean
	        </entry>
	        <entry>
		  If <literal>tcp_nodelay='true'</literal>, TCP packet
		  batching is disabled.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sasl_protocol
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  Used only for
		  Kerberos. <literal>sasl_protocol</literal> must be
		  set to the principal for the qpidd broker,
		  e.g. <literal>qpidd/</literal>
	        </entry>
	      </row>
	      <row>
	        <entry>
		  sasl_server
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  For Kerberos, sasl_mechs must be set to GSSAPI,
		  sasl_server must be set to the host for the SASL
		  server, e.g. <literal>sasl.com</literal>.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  trust_store
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  path to Keberos trust store
	        </entry>
	      </row>
	      <row>
	        <entry>
		  trust_store_password
	        </entry>
	        <entry>
	        </entry>
	        <entry>
		  Kerberos trust store password
	        </entry>
	      </row>
	      <row>
	        <entry>
		  key_store
	        </entry>
	        <entry>
	        </entry>
	        <entry>
		  path to Kerberos key store
	        </entry>
	      </row>
	      <row>
	        <entry>
		  key_store_password
	        </entry>
	        <entry>
		  --
	        </entry>
	        <entry>
		  Kerberos key store password
	        </entry>
	      </row>
	      <row>
	        <entry>
		  ssl_verify_hostname
	        </entry>
	        <entry>
		  Boolean
	        </entry>
	        <entry>
		  When using SSL you can enable hostname verification
		  by using "ssl_verify_hostname=true" in the broker
		  URL.
	        </entry>
	      </row>
	      <row>
	        <entry>
		  ssl_cert_alias
	        </entry>
	        <entry>

	        </entry>
	        <entry>
          If multiple certificates are present in the keystore, the alias will be used to extract the correct certificate.
	        </entry>
	      </row>
	    </tbody>
	  </tgroup>
	</table>
      </section>
    </section>  

    <section>
      <title>Java JMS Message Properties</title>

      <para>The following table shows how Qpid Messaging API message
        properties are mapped to AMQP 0-10 message properties and
        delivery properties. In this table <varname>msg</varname>
        refers to the Message class defined in the Qpid Messaging API,
        <varname>mp</varname> refers to an AMQP 0-10
        <varname>message-properties</varname> struct, and
        <varname>dp</varname> refers to an AMQP 0-10
        <varname>delivery-properties</varname> struct.</para>

      <table >
        <title>Java JMS Mapping to AMQP 0-10 Message Properties</title>
        <tgroup cols="2">
          <thead>
	    <row>
	      <entry>Java JMS Message Property</entry>
	      <entry>AMQP 0-10 Property<footnote><para>In these entries, <literal>mp</literal> refers to an AMQP message property, and <literal>dp</literal> refers to an AMQP delivery property.</para></footnote></entry>

	    </row>
          </thead>
          <tbody>
	    <row>
	      <entry>JMSMessageID</entry><entry>mp.message_id</entry>
	    </row>
	    <row>
	      <entry>qpid.subject<footnote><para>This is a custom JMS property, set automatically by the Java JMS client implementation.</para></footnote></entry><entry>mp.application_headers["qpid.subject"]</entry>
	    </row>
	    <row>
	      <entry>JMSXUserID</entry><entry>mp.user_id</entry>
	    </row>
	    <row>
	      <entry>JMSReplyTo</entry><entry>mp.reply_to<footnote><para>The reply_to is converted from the protocol representation into an address.</para></footnote></entry>
	    </row>
	    <row>
	      <entry>JMSCorrelationID</entry><entry>mp.correlation_id</entry>
	    </row>
	    <row>
	      <entry>JMSDeliveryMode</entry><entry>dp.delivery_mode</entry>
	    </row>
	    <row>
	      <entry>JMSPriority</entry><entry>dp.priority</entry>
	    </row>
	    <row>
	      <entry>JMSExpiration</entry><entry>dp.ttl<footnote><para>JMSExpiration = dp.ttl + currentTime</para></footnote></entry>
	    </row>
	    <row>
	      <entry>JMSRedelivered</entry><entry>dp.redelivered</entry>
	    </row>
	    <row>
	      <entry>JMS Properties</entry><entry>mp.application_headers</entry>
	    </row>
	    <row>
	      <entry>JMSType</entry><entry>mp.content_type</entry>
	    </row>
          </tbody>
        </tgroup>
      </table>
      
    </section>

    <section id="section-JMS-MapMessage">
      <title>JMS MapMessage Types</title>

      <para>Qpid supports the Java JMS <classname>MapMessage</classname> interface, which provides support for maps in messages. The following code shows how to send a <classname>MapMessage</classname> in Java JMS.</para>

      <example>
	<title>Sending a Java JMS MapMessage</title>
      <programlisting><![CDATA[
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.jms.Connection;
import javax.jms.Destination;
import javax.jms.MapMessage;
import javax.jms.MessageProducer;
import javax.jms.Session;

import org.apache.qpid.client.AMQAnyDestination;
import org.apache.qpid.client.AMQConnection;

import edu.emory.mathcs.backport.java.util.Arrays;

// !!! SNIP !!!

MessageProducer producer = session.createProducer(queue);

MapMessage m = session.createMapMessage();
m.setIntProperty("Id", 987654321);
m.setStringProperty("name", "Widget");
m.setDoubleProperty("price", 0.99);

List<String> colors = new ArrayList<String>();
colors.add("red");
colors.add("green");
colors.add("white");        
m.setObject("colours", colors);

Map<String,Double> dimensions = new HashMap<String,Double>();
dimensions.put("length",10.2);
dimensions.put("width",5.1);
dimensions.put("depth",2.0);
m.setObject("dimensions",dimensions);

List<List<Integer>> parts = new ArrayList<List<Integer>>();
parts.add(Arrays.asList(new Integer[] {1,2,5}));
parts.add(Arrays.asList(new Integer[] {8,2,5}));
m.setObject("parts", parts);

Map<String,Object> specs = new HashMap<String,Object>();
specs.put("colours", colors);
specs.put("dimensions", dimensions);
specs.put("parts", parts);
m.setObject("specs",specs);

producer.send(m);
      ]]></programlisting>
      </example>

      <para>The following table shows the datatypes that can be sent in a <classname>MapMessage</classname>, and the corresponding datatypes that will be received by clients in Python or C++.</para>
      
      <table id="table-Java-Maps">
	<title>Java Datatypes in Maps</title>
	<tgroup cols="3">
	  <thead>
	    <row>
	      <entry>Java Datatype</entry>
	      <entry>&rarr; Python</entry>
	      <entry>&rarr; C++</entry>
	    </row>
	  </thead>
	  <tbody>
   	    <row><entry>boolean</entry><entry>bool</entry><entry>bool</entry></row>
	    <row><entry>char</entry><entry>unicode<footnote><para>The Python string will contain one Unicode character</para></footnote></entry><entry>int</entry></row>
	    <row><entry>short</entry><entry>integer | long</entry><entry>short</entry></row>
	    <row><entry>integer</entry><entry>integer | long</entry><entry>int</entry></row>
	    <row><entry>long</entry><entry>integer | long</entry><entry>long</entry></row>
	    <row><entry>float</entry><entry>float</entry><entry>float</entry></row>
	    <row><entry>double</entry><entry>float</entry><entry>double</entry></row>
	    <row><entry>java.lang.String</entry><entry>unicode</entry><entry>std::string</entry></row>
	    <row><entry>java.util.UUID</entry><entry>uuid</entry><entry>qpid::types::Uuid</entry></row>
	    <row><entry>java.util.Map</entry><entry>dict</entry><entry>Variant::Map</entry></row>
	    <row><entry>java.util.List</entry><entry>list</entry><entry>Variant::List</entry></row>
	  </tbody>
	</tgroup>
      </table>

    </section>

    <section>
      <title>Java JMS Selector Syntax</title>
      <para>The AMQP Java JMS Messaging Client supports the following syntax for JMS selectors.</para>


      <formalpara><title>Comments:</title>
      <para>
      <programlisting><![CDATA[LINE_COMMENT: "--" (~["\n","\r"])* EOL
EOL: "\n"|"\r"|"\r\n"
BLOCK_COMMENT: "/*" (~["*"])* "*" ("*" | (~["*","/"] (~["*"])* "*"))* "/"
]]></programlisting>
      </para>
      </formalpara>

      <formalpara><title>Reserved Words (case insensitive)</title>
      <para>
      <programlisting><![CDATA[NOT:     "NOT"
AND:     "AND"
OR:      "OR"
BETWEEN: "BETWEEN"
LIKE:    "LIKE"
ESCAPE:  "ESCAPE"
IN:      "IN"
IS:      "IS"
TRUE:    "TRUE"
FALSE:   "FALSE"
NULL:    "NULL"
]]></programlisting>
      </para>
      </formalpara>

      <formalpara><title>Literals (case insensitive)</title>
      <para>
      <programlisting><![CDATA[DECIMAL_LITERAL:        ["1"-"9"] (["0"-"9"])* (["l","L"])?
HEX_LITERAL:            "0" ["x","X"] (["0"-"9","a"-"f","A"-"F"])+
OCTAL_LITERAL:          "0" (["0"-"7"])*
FLOATING_POINT_LITERAL: ( 
 (["0"-"9"])+ "." (["0"-"9"])* (<EXPONENT>)? // eg: 5.5 or 5. or 5.5E10 or 5.E10
  | "." (["0"-"9"])+ (<EXPONENT>)?           // eg: .5 or .5E10
  | (["0"-"9"])+ <EXPONENT>                  // eg: 5E10
)                 
EXPONENT:               "E" (["+","-"])? (["0"-"9"])+
STRING_LITERAL:         "'" ( ("''") | ~["'"] )*  "'"
]]></programlisting>
      </para>
      </formalpara>


      <formalpara><title>Identifiers (case insensitive)</title>
      <para>
      <programlisting><![CDATA[ID : ["a"-"z", "_", "$"] (["a"-"z","0"-"9","_", "$"])*
QUOTED_ID : "\"" ( ("\"\"") | ~["\""] )*  "\""
]]></programlisting>
      </para>
      </formalpara>


      <formalpara><title>Grammar</title>
      <para>
      <programlisting><![CDATA[JmsSelector        := orExpression
orExpression       := ( andExpression ( <OR> andExpression )* )
andExpression      := ( equalityExpression ( <AND> equalityExpression )* )
equalityExpression := ( comparisonExpression (   "=" comparisonExpression
                                                 | "<>" comparisonExpression
                                                 | <IS> <NULL>
                                                 | <IS> <NOT> <NULL> )* )
comparisonExpression := 
    ( addExpression 
      (   ">" addExpression
        | ">=" addExpression
        | "<" addExpression
        | "<=" addExpression
        | <LIKE> stringLitteral ( <ESCAPE> stringLitteral )?
        | <NOT> <LIKE> <STRING_LITERAL> ( <ESCAPE> <STRING_LITERAL> )?
        | <BETWEEN> addExpression <AND> addExpression
        | <NOT> <BETWEEN> addExpression <AND> addExpression
        | <IN> "(" <STRING_LITERAL> ( "," <STRING_LITERAL> )* ")"
        | <NOT> <IN> "(" <STRING_LITERAL> ( "," <STRING_LITERAL> )* ")" 
      )*  
    )

addExpression := multExpr ( ( "+" multExpr | "-" multExpr ) )*
multExpr      := unaryExpr ( "*" unaryExpr | "/" unaryExpr | "%" unaryExpr )*
unaryExpr     := ( "+" unaryExpr | "-" unaryExpr | <NOT> unaryExpr | primaryExpr )
primaryExpr   := ( literal | variable | "(" orExpression ")" )
literal       := (   <STRING_LITERAL>
                   | <DECIMAL_LITERAL>
                   | <HEX_LITERAL>
                   | <OCTAL_LITERAL>
                   | <FLOATING_POINT_LITERAL>
                   | <TRUE>
                   | <FALSE>
                   | <NULL> 
                 )

variable             := ( <ID> | <QUOTED_ID> )]]></programlisting>
      </para>
      </formalpara>

    </section>

  </chapter>
</book>

<!--
   - client code remains exactly the same, but routing behavior
   changes
   - exchanges drop messages if nobody is listening, so we need to
   start drain first
   - drain will exit immediately if the source is empty (note that
   this is actually a semantic guarantee provided by the API, we
   know for a fact that the source is empty when drain/fetch
   reports it, no fudge factor timeout is required [this assumes
   nobody is concurrently publishing of course])
   - drain -f invokes blocking fetch (you could use a timeout here also)
  -->