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diff --git a/content/xdocs/CppHandlerChains.html b/content/xdocs/CppHandlerChains.html new file mode 100755 index 0000000000..7896cc8feb --- /dev/null +++ b/content/xdocs/CppHandlerChains.html @@ -0,0 +1,76 @@ +<html> + <head> + <title>Apache Qpid : CppHandlerChains</title> + <link rel="stylesheet" href="styles/site.css" type="text/css" /> + <META http-equiv="Content-Type" content="text/html; charset=UTF-8"> + </head> + + <body> + <table class="pagecontent" border="0" cellpadding="0" cellspacing="0" width="100%" bgcolor="#ffffff"> + <tr> + <td valign="top" class="pagebody"> + <div class="pageheader"> + <span class="pagetitle"> + Apache Qpid : CppHandlerChains + </span> + </div> + <div class="pagesubheading"> + This page last changed on Sep 20, 2007 by <font color="#0050B2">aconway</font>. + </div> + + <p>The C++ broker uses handler chains to break complex processing into individual pieces.</p> + +<ul> + <li>Each session has its own set of FrameHandler chains.</li> + <li>Frames from the network are delivered to the first handler in the chain.</li> + <li>Handlers do something with a frame, then pass it to the next handler.</li> + <li>Handlers may "filter" frames by not passing some frames to the next handler.</li> +</ul> + + +<h1><a name="CppHandlerChains-Currentstatus%282002%2F9%2F20%29"></a>Current status (2002/9/20)</h1> + +<p>Each chain starts with a SessionHandler. It handles L2 (session open, close etc.) and passes other frames to the next handler.</p> + +<p>L3/L4 frames are handled by the SemanticHandler.</p> + +<p>For clustering, a ClusterHandler is inserted at the start of the chain. It replicates frames to a backup broker so the backup can handle failover. It then passes frames on to the normal session handlers.</p> + +<h1><a name="CppHandlerChains-Approachformultiframesegments"></a>Approach for multi-frame segments</h1> + +<ul> + <li>The frame handler chain continues to handle individual frames.</li> + <li>Each handler uses a FrameSet to accumulate its frames.</li> + <li>Frame no longer contains a Body, moved to FrameSet +<div class="code"><div class="codeContent"> +<pre class="code-java">class FrameSet { <span class="code-comment">// sketch
+</span> void add(<span class="code-keyword">const</span> Frame& frame); <span class="code-comment">// True <span class="code-keyword">if</span>
+</span> <span class="code-keyword">const</span> AMQMethodBody* getMethod(); <span class="code-comment">// 0 means not complete.
+</span> <span class="code-keyword">const</span> AMQHeaderBody* getHeader();
+ <span class="code-keyword">const</span> AMQContentBody* getContent();
+};</pre> +</div></div> +<p>Note: All the visitor/dispatch classes using AMQFrame need to be reworked. Dispatch will always be based on an AMQMethodBody, not a frame. </p></li> +</ul> + + +<p>Rationale: </p> + +<p>''Frame rather than Segment/FrameSet handlers'': Allows most flexibility to compose or not compose frames into segments & FrameSets. For example a cluster handler needs to replicate frame-by-frame, so we don't want to compose the full segment up front. Since the FrameSet class provides the composition logic, this is specified only once and easy to use in frame handlers.</p> + +<p>''No Segment class'': A segment by itself is not very useful. A non-content method is just a FrameSet containing a single method segment. For content bearing methods are a frameset with headers & content. There's little value for a stand alone segment class.</p> + + + </td> + </tr> + </table> + <table border="0" cellpadding="0" cellspacing="0" width="100%"> + <tr> + <td height="12" background="border/border_bottom.gif"><img src="border/spacer.gif" width="1" height="1" border="0"/></td> + </tr> + <tr> + <td align="center"><font color="grey">Document generated by Confluence on Apr 22, 2008 02:47</font></td> + </tr> + </table> + </body> +</html>
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