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From build...@apache.org
Subject svn commit: r966538 - in /websites/production/cxf/content: cache/docs.pageCache docs/using-apache-htrace.html
Date Thu, 24 Sep 2015 00:47:28 GMT
Author: buildbot
Date: Thu Sep 24 00:47:28 2015
New Revision: 966538

Log:
Production update by buildbot for cxf

Modified:
    websites/production/cxf/content/cache/docs.pageCache
    websites/production/cxf/content/docs/using-apache-htrace.html

Modified: websites/production/cxf/content/cache/docs.pageCache
==============================================================================
Binary files - no diff available.

Modified: websites/production/cxf/content/docs/using-apache-htrace.html
==============================================================================
--- websites/production/cxf/content/docs/using-apache-htrace.html (original)
+++ websites/production/cxf/content/docs/using-apache-htrace.html Thu Sep 24 00:47:28 2015
@@ -117,18 +117,18 @@ Apache CXF -- Using Apache HTrace
            <!-- Content -->
            <div class="wiki-content">
 <div id="ConfluenceContent"><p><style type="text/css">/*<![CDATA[*/
-div.rbtoc1442458012720 {padding: 0px;}
-div.rbtoc1442458012720 ul {list-style: disc;margin-left: 0px;}
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+div.rbtoc1443055616092 {padding: 0px;}
+div.rbtoc1443055616092 ul {list-style: disc;margin-left: 0px;}
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-/*]]>*/</style></p><div class="toc-macro rbtoc1442458012720">
+/*]]>*/</style></p><div class="toc-macro rbtoc1443055616092">
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Overview">Overview</a></li><li><a
shape="rect" href="#UsingApacheHTrace-DistributedTracinginNutshell">Distributed Tracing
in Nutshell</a></li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracinginApacheCXF">Distributed
Tracing in Apache CXF</a></li><li><a shape="rect" href="#UsingApacheHTrace-ConfiguringClientconfigure.client">Configuring
Client</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Configuringtracingheadernames">Configuring
tracing header names</a></li></ul>
 </li><li><a shape="rect" href="#UsingApacheHTrace-ConfiguringServerconfigure.server">Configuring
Server</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Configuringtracingheadernames.1">Configuring
tracing header names</a></li></ul>
 </li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracingInAction:UsageScenarios">Distributed
Tracing In Action: Usage Scenarios</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Example#1:ClientandServerwithdefaultdistributedtracingconfigured">Example
#1: Client and Server with default distributed tracing configured</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#2:ClientandServerwithnestedtrace">Example
#2: Client and Server with nested trace</a></li><li><a shape="rect" href="#UsingApacheHTrace-Example#3:ClientandServertracewithtimeline">Example
#3: Client and Server trace with timeline</a></li><li><a shape="rect"
href="#UsingApacheHTrace-Example#4:ClientandServerwithannotatedtrace(key/value)">Example
#4: Client and Server with annotated trace (key/value)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#5:ClientandServerwithparalleltrace(involvingthreadpools)">Example
#5: Client and Server with parallel trace (involving thread pools)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#6:ClientandServerwithasynchronousJAX-RSservice(server-side)">Exampl
 e #6: Client and Server with asynchronous JAX-RS service (server-side)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#7:ClientandServerwithasynchronousinvocation(client-side)">Example
#7: Client and Server with asynchronous invocation (client-side)</a></li></ul>
-</li><li><a shape="rect" href="#UsingApacheHTrace-FutureWork">Future Work</a></li></ul>
+</li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracingandJAX-WSsupport">Distributed
Tracing and JAX-WS support</a></li><li><a shape="rect" href="#UsingApacheHTrace-FutureWork">Future
Work</a></li></ul>
 </div><h1 id="UsingApacheHTrace-Overview">Overview</h1><p><a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is a tracing framework intended for use with distributed systems written in java. Since version
<strong>3.1.3</strong>, Apache CXF fully supports integration with <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>,
both on client side and server side. This section gives a complete overview on how distributed
tracing support is supported in JAX-RS applications built on top of Apache CXF.</p><h1
id="UsingApacheHTrace-DistributedTracinginNutshell">Distributed Tracing in Nutshell</h1><p>Distributed
tracing, first described by Google in <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper became increasingly important topic these days. With 
 microservices (aka SOA) gaining more and more adoption, the typical applications are built
using dozens or even hundreds of small, distributed pieces. The end-to-end traceability of
the requests (or any kind of work performed on user's behalf) is hard task to accomplish,
particularly taking into account asyncronous or/and concurrent invocations. <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is inspired by <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper and essentially is a full-fledged distributed tracing framework.</p><p>Distributed
tracing is additional instrumentation layer on top of new or existing applications. In terms
of distributed tracing, <strong>span</strong> represents a basic unit of work.
For example, executing database query is a <strong>span</strong>. <strong>Spans</strong>

 are identified by a unique 64-bit ID for the <strong>span</strong> and another
64-bit ID for the <strong>trace</strong> the span is a <strong>part</strong>
of. <strong>Spans</strong> also have other data, such as <strong>descriptions</strong>,
<strong>timelines</strong>,<strong> key-value annotations</strong>,
the <strong>ID</strong> of the <strong>span</strong> that caused them
(parent), and <strong>process</strong> ID&#8217;s (normally IP address and
process name). Spans are started and stopped, and they keep track of their timing information.
Once <strong>span</strong> is created, it should be stopped at some point in the
future. In turn, <strong>trace</strong> is a set of spans forming a tree-like
structure. For example, if you are running a JAX-RS service, a trace might be formed by a
<strong>PUT</strong> request.</p><p>From implementation prospective,
and in context of Java applications, <strong>spans</strong> are attached to their
threads (in general, thread which created the
  <strong>span</strong> should close it). However it is possible to transfer <strong>spans</strong>
from thread to thread in order to model a complex execution flows. It is also possible to
have many <strong>spans</strong> in the same thread, as long as they are properly
created and closed. In the next sections we are going to see the examples of that.</p><p>Another
two important concepts of in context of distributed tracing are <strong>span receivers</strong>
and <strong>samplers</strong>. Essentially, all spans (including start/stop time,
key/value annotations, timelines, ..) should be persisted (or collected) somewhere. <strong>Span
receiver</strong> is a collector within a process that is the destination of <strong>spans</strong>
when a trace is running (it could be a console, local file, data store, ...). <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
provides span receivers for <a shape="rect" class="external-link" h
 ref="http://hbase.apache.org">Apache HBase</a>, <a shape="rect" class="external-link"
href="https://flume.apache.org/">Apache Flume</a> and <a shape="rect" class="external-link"
href="http://zipkin.io/" rel="nofollow">Twitter Zipkin</a>. From other side, <strong>samplers</strong>
allow to control the frequency of the tracing (all the time, never, probability driven, ...).
Using the <strong>sampler</strong> is the way to minimize tracing overhead (or
just amount of traces) by limiting them to particular conditions.</p><h1 id="UsingApacheHTrace-DistributedTracinginApacheCXF">Distributed
Tracing in Apache CXF</h1><p><a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is a very popular framework for building services and web APIs. No doubts, it
is going to play even more important role in context of microservices architecture letting
developers to quickly build and deploy individual JAX-RS/JAX-WS services. As it was just mentioned
before, distributed tracing is an essential tec
 hnique to monitor the application as whole, breaking the request to individual service traces
as it goes through and crosses the boundaries of threads, processes and machines.</p><p>The
current integration of distributed tracing in <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> supports <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> only in JAX-RS 2.x applications. From high-level prospective, it consists
of three main parts:</p><ul style="list-style-type: square;"><li><strong>TracerContext</strong>
(injectable through <strong>@Context</strong> annotation)</li><li><strong>HTraceProvider</strong>
(server-side JAX-RS provider) and <strong>HTraceClientProvider</strong> (client-side
JAX-RS provider)</li><li><strong>HTraceFeature</strong> (server-side
<a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> feature to simplify
<a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/inde
 x.html">Apache HTrace</a> configuration and integration)</li></ul><p><a
shape="rect" href="http://cxf.apache.org/">Apache CXF</a> uses HTTP headers to hand
off tracing context from the client to the service and from the service to service. Those
headers are used internally by <strong>HTraceProvider</strong> and <strong>HTraceClientProvider</strong>,
but are configurable. The default header names are declared in the TracerHeaders class:</p><ul
style="list-style-type: square;"><li><strong>X-Trace-Id</strong>: contains
a current trace ID</li><li><strong>X-Span-Id</strong>: contains a
current span ID</li></ul><p>By default, <strong>HTraceProvider</strong>
will try pass the currently active <strong>span</strong> through HTTP headers
on each service invocation. If there is no active span, the new span will be created and passed
through HTTP headers on per-invocation basis. Essentially, just registering the <strong>HTraceProvider</strong>
on the client and <strong>HTraceClientProvider</str
 ong> on the server is enough to have tracing context to be properly passed everywhere.
The only configuration part which is necessary are <strong>span receiver(s)</strong>
and <strong>sampler</strong>.</p><p>It is also worth to mention the
way <a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> attaches the
description to <strong>spans</strong>. With regards to the client integration,
the description becomes a full URL being invoked prefixed by HTTP method, for example: <strong>GET
</strong><a shape="rect" class="external-link" href="http://localhost:8282/books"
rel="nofollow"><strong>http://localhost:8282</strong>/books</a>. On the
server side integration, the description becomes a relation JAX-RS resource path prefixed
by HTTP method, f.e.: <strong>GET books, POST book/123</strong></p><h1
id="UsingApacheHTrace-ConfiguringClientconfigure.client">Configuring Client <span class="confluence-anchor-link"
id="UsingApacheHTrace-configure.client"></span></h1><p>There are a couple
  of way the JAX-RS client could be configured, depending on the client implementation. <a
shape="rect" href="http://cxf.apache.org/">Apache CXF</a> provides its own <strong>WebClient</strong>
which could be configured just like that (in future versions, there would be a simpler ways
to do that using client specific features):</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
 <pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">final
Map&lt;String, String&gt; properties = new HashMap&lt;String, String&gt;();
 final HTraceConfiguration conf = HTraceConfiguration.fromMap(properties);
@@ -310,7 +310,18 @@ public Collection&lt;Book&gt; getBooks()
     .accept(MediaType.APPLICATION_JSON)
     .async()
     .get();</pre>
-</div></div><p>In this respect, there is no difference from the caller
prospective however a bit more work is going under the hood to transfer the active tracing
span from JAX-RS client request filter to client response filter as in general those are executed
in different threads (similarly to server-side asynchronous JAX-RS resource invocation). The
actual invocation of the request by the client (with process name <strong><span class="label
label-default service-filter-label service-tag-filtered">jaxrsclient/192.168.0.100</span></strong>)
and consequent invocation of the service on the server side (process name<strong> <span
class="label label-default service-filter-label">jaxrsserver/192.168.0.100</span></strong>)
is going to generate the following sample traces:</p><p><span class="confluence-embedded-file-wrapper
confluence-embedded-manual-size"><img class="confluence-embedded-image" height="250"
src="using-apache-htrace.data/image2015-9-16%2021:9:56.png"></span></p><h1
id="Using
 ApacheHTrace-FutureWork">Future Work</h1><p>The <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is very proud to offer <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> integration. At the current stage, it was a conscious decision to keep the
minimal API and provide the set of necessary features only. However, there is a strong commitment
to evolve not only <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> integration, but the distributed tracing support in general.</p></div>
+</div></div><p>In this respect, there is no difference from the caller
prospective however a bit more work is going under the hood to transfer the active tracing
span from JAX-RS client request filter to client response filter as in general those are executed
in different threads (similarly to server-side asynchronous JAX-RS resource invocation). The
actual invocation of the request by the client (with process name <strong><span class="label
label-default service-filter-label service-tag-filtered">jaxrsclient/192.168.0.100</span></strong>)
and consequent invocation of the service on the server side (process name<strong> <span
class="label label-default service-filter-label">jaxrsserver/192.168.0.100</span></strong>)
is going to generate the following sample traces:</p><p><span class="confluence-embedded-file-wrapper
confluence-embedded-manual-size"><img class="confluence-embedded-image" height="250"
src="using-apache-htrace.data/image2015-9-16%2021:9:56.png"></span></p><h1
id="Using
 ApacheHTrace-DistributedTracingandJAX-WSsupport">Distributed Tracing and JAX-WS support</h1><p>Distributed
tracing in the <a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> is
build primarily around JAX-RS 2.x implementation. However, JAX-WS is also supported but it
requires to write some boiler-plate code and use <a shape="rect" class="external-link"
href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a> API directly
(the JAX-WS integration is going to be enhanced in the nearest future). Essentially, from
the server-side prospective the in/out interceptors,&#160;<strong>HTraceStartInterceptor</strong>
and&#160;<strong>HTraceStopInterceptor </strong>respectively, should be configured
as part of interceptor chains. The <strong>span</strong> receiver should be configured
manually though, using <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> API, for example:</p><div class="code panel pdl" style="bor
 der-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">final
Map&lt;String, String&gt; properties = new HashMap&lt;String, String&gt;();
+final HTraceConfiguration conf = HTraceConfiguration.fromMap(properties);
+Trace.addReceiver(new StandardOutSpanReceiver(conf));
+            
+final JaxWsServerFactoryBean sf = new JaxWsServerFactoryBean();
+...
+sf.getInInterceptors().add(new HTraceStartInterceptor(Phase.PRE_INVOKE, new AlwaysSampler(conf)));
+sf.getOutInterceptors().add(new HTraceStopInterceptor(Phase.PRE_MARSHAL));
+...
+sf.create();</pre>
+</div></div><div class="confluence-information-macro confluence-information-macro-information"><span
class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>Configuring right phases for interceptors
is very important. The recommended phase for in-interceptor is <strong>PRE_INVOKE</strong>
while for out-interceptor is <strong>PRE_MARSHAL</strong>. If wrong phases are
being used, response or/and request headers could be ignored or not processed.</p></div></div><p>TODO:
Client side</p><h1 id="UsingApacheHTrace-FutureWork">Future Work</h1><p>The
<a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> is very proud to
offer <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> integration. At the current stage, it was a conscious decision to keep the
minimal API and provide the set of necessary features only. However, there is a strong commitmen
 t to evolve not only <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> integration, but the distributed tracing support in general.</p></div>
            </div>
            <!-- Content -->
          </td>



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