QPID-6165 : Add documentation for port connection limits

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1641817 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 54 insertions, 1 deletions

diff --git a/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Background-Recovery.xml b/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Background-Recovery.xml
index 33294bf7c5..99f05c4544 100644
--- a/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Background-Recovery.xml
+++ b/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Background-Recovery.xml
@@ -28,7 +28,7 @@
     take considerable time. During this time no messaging can be performed.</para>
   <para>The Broker has a background recovery feature allows the system to return to operation
     sooner. If enabled the recovery process takes place in the background allow producers and
-    consumers to being work earlier.</para>
+    consumers to begin work earlier.</para>
   <para>The feature respects the message delivery order requirements of standard queues, that is any
     messages arriving whilst the background recovery is in flight won't overtake older messages
     still to be recovered from disk. There is an exception for the out of order queue types whilst
diff --git a/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Connection-Limit.xml b/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Connection-Limit.xml
new file mode 100644
index 0000000000..06cf6a6631
--- /dev/null
+++ b/qpid/doc/book/src/java-broker/Java-Broker-Runtime-Connection-Limit.xml
@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+
+-->
+
+<section id="Java-Broker-Runtime-Connection-Limit">
+  <title>Connection Limits</title>
+  <para>
+     Each connection to the Broker consumes resources while it is connected. In order to protect
+     the Broker against malfunctioning (or malicious) client processes, it is possible to limit the
+     number of connections that can be active on any given port.
+   </para>
+   <para>
+       Connection limits on AMQP ports are controlled by an attribute "maxOpenConnections" on
+       the port. By default this takes the value of the context variable 
+       <literal>qpid.port.max_open_connections</literal> which in itself is defaulted to the
+       value <literal>-1</literal> meaning there is no limit.
+   </para>
+   <para>
+       If the interpolated value of <literal>maxOpenConnections</literal> on an AMQP port is a
+       positive integer, then when that many active connections have been established no new
+       connections will be allowed (until an existing connection has been closed). Any such 
+       rejection of a connection will be accompanied by the operational log message
+       <link linkend="Java-Broker-Appendix-Operation-Logging-Message-PRT-1005">PRT-1005</link>.
+   </para>
+   <para>
+       The context variable <literal>qpid.port.open_connections_warn_percent</literal> can be 
+       used to control when a warning log message is generated as the number of open connections
+       approaches the limit for the port. The default value of this variable is 
+       <literal>80</literal> meaning that if more the number of open connections to the port
+       has exceeded 80% of the given limit then the operatinal log message 
+       <link linkend="Java-Broker-Appendix-Operation-Logging-Message-PRT-1004">PRT-1004</link>
+       will be generated.
+   </para>
+</section>
diff --git a/qpid/doc/book/src/java-broker/Java-Broker-Runtime.xml b/qpid/doc/book/src/java-broker/Java-Broker-Runtime.xml
index cd214de26d..25dc7e9684 100644
--- a/qpid/doc/book/src/java-broker/Java-Broker-Runtime.xml
+++ b/qpid/doc/book/src/java-broker/Java-Broker-Runtime.xml
@@ -33,4 +33,5 @@
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="Java-Broker-Runtime-Flow-To-Disk.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="Java-Broker-Runtime-Background-Recovery.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="Java-Broker-Runtime-Message-Compression.xml"/>
+  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="Java-Broker-Runtime-Connection-Limit.xml"/>
 </chapter>