Author: buildbot
Date: Mon Jan 30 22:47:06 2017
New Revision: 1005944
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 Mon Jan 30
22:47:06 2017
@@ -117,19 +117,19 @@ Apache CXF -- Using Apache HTrace
<!-- Content -->
<div class="wiki-content">
<div id="ConfluenceContent"><p><style type="text/css">/*<![CDATA[*/
-div.rbtoc1445395593960 {padding: 0px;}
-div.rbtoc1445395593960 ul {list-style: disc;margin-left: 0px;}
-div.rbtoc1445395593960 li {margin-left: 0px;padding-left: 0px;}
+div.rbtoc1485816393306 {padding: 0px;}
+div.rbtoc1485816393306 ul {list-style: disc;margin-left: 0px;}
+div.rbtoc1485816393306 li {margin-left: 0px;padding-left: 0px;}
-/*]]>*/</style></p><div class="toc-macro rbtoc1445395593960">
-<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>
+/*]]>*/</style></p><div class="toc-macro rbtoc1485816393306">
+<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-DistributedTracinginApacheCXFusingApacheHTrace">Distributed
Tracing in Apache CXF using Apache HTrace</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-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 128-bit ID. <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/tracer</strong> ID’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 and
downstream work.</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</str
ong> 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 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"
href="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 technique 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>
(<strong>4.x+</strong> release branch) 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/index.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-Span-Id</strong>:
contains a current span ID</li></ul><p>By default,
<strong>HTraceProvider</strong> will try to pass the currently active
<strong>span</strong> through HTTP headers on each service invocation. If there
is no active spans, 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</strong> on the server is enough to have tracing
context to be properly passed everywhere. The only configuration part whic
h is necessary are <strong>span receiver(s)</strong> and
<strong>sampler</strong>(s).</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
ways 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">
+</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 128-bit ID. <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/tracer</strong> ID’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 and
downstream work.</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</str
ong> 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 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"
href="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-DistributedTracinginApacheCXFusingApacheHTrace">Distributed
Tracing in Apache CXF using Apache HTrace</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 technique to monitor the
application as whole, breaking the req
uest 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>
(<strong>4.x+</strong> release branch) 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/index.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-Span-Id</strong>: contains a current span
ID</li></ul><p>By default, <strong>HTraceProvider</strong> will try to pass the
currently active <strong>span</strong> through HTTP headers on each service
invocation. If there is no active spans, 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</strong> on the server is enough to have tracing
context to be properly passed everywh
ere. The only configuration part which is necessary are <strong>span
receiver(s)</strong> and <strong>sampler</strong>(s).</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
ways the JAX-RS client could be configured, depending on the client impleme
ntation. <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<String, String> properties = new
HashMap<String, String>();
properties.put(Tracer.SPAN_RECEIVER_CLASSES_KEY, ...);
properties.put(Tracer.SAMPLER_CLASSES_KEY, ...);
