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Dave Syer
2014-12-26 15:10:53 +00:00
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@@ -477,8 +477,18 @@ body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-b
<li><a href="#_turbine">Turbine</a></li>
</ul>
</li>
<li><a href="#spring-cloud-feign">Declarative REST Client: Feign</a></li>
<li><a href="#spring-cloud-ribbon">Client Side Load Balancer: Ribbon</a></li>
<li><a href="#spring-cloud-feign">Declarative REST Client: Feign</a>
<ul class="sectlevel2">
<li><a href="#spring-cloud-feign-without-eureka">Example: How to Use Feign Without Eureka</a></li>
</ul>
</li>
<li><a href="#spring-cloud-ribbon">Client Side Load Balancer: Ribbon</a>
<ul class="sectlevel2">
<li><a href="#_customizing_the_ribbon_client">Customizing the Ribbon Client</a></li>
<li><a href="#_using_the_ribbon_api_directly">Using the Ribbon API Directly</a></li>
<li><a href="#_spring_resttemplate_as_a_ribbon_client">Spring RestTemplate as a Ribbon Client</a></li>
</ul>
</li>
<li><a href="#_external_configuration_archaius">External Configuration: Archaius</a></li>
<li><a href="#_router_and_filter_zuul">Router and Filter: Zuul</a>
<ul class="sectlevel2">
@@ -1608,7 +1618,10 @@ is more convenient to use it behind a wrapper of some sort. Spring
Cloud has support for <a href="#spring-cloud-feign">Feign</a> (a REST client
builder) and also <a href="#spring-cloud-ribbon">Spring <code>RestTemplate</code></a> using
the logical Eureka service identifiers (VIPs) instead of physical
URLs.</p>
URLs. To configure Ribbon with a fixed list of physical servers you
can simply set <code>&lt;client&gt;.ribbon.listOfServers</code> to a comma-separated
list of physical addresses (or hostnames), where <code>&lt;client&gt;</code> is the ID
of the client.</p>
</div>
</div>
<div class="sect2">
@@ -2008,13 +2021,86 @@ public interface StoreClient {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>In the <code>@FeignClient</code> annotation the String value ("stores" above) is
the arbitrary name of the client, used to create a configuration
prefix (see <a href="#spring-cloud-ribbon">below for details of Ribbon
support</a>).</p>
</div>
<div class="sect2">
<h3 id="spring-cloud-feign-without-eureka">Example: How to Use Feign Without Eureka</h3>
<div class="paragraph">
<p>Eureka is a convenient way to abstract the discovery of remote servers
so you don&#8217;t have to hard code their URLs in clients, but if you
prefer not to use it, Ribbon and Feign are still quite
amenable. Suppose you have declared a Feign client as above for
"stores", and Eureka is not in use (and not even on the
classpath). You should find that the Ribbon client defaults to a
configured server list, and you can supply the configuration like this</p>
</div>
<div class="listingblock">
<div class="title">application.yml</div>
<div class="content">
<pre>stores:
ribbon:
listOfClients: example.com,google.com</pre>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="spring-cloud-ribbon">Client Side Load Balancer: Ribbon</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Usage of <code>LoadBalancerClient</code> directly:</p>
<p>Ribbon is a client side load balancer which gives you a lot of control
over the behaviour of HTTP and TCP clients. Feign already uses Ribbon,
so if you are using <code>@FeignClient</code> then this section also applies.</p>
</div>
<div class="paragraph">
<p>A central concept in Ribbon is that of the named client. Each load
balancer is part of an ensemble of components that work together to
contact a remote server on demend, and the ensemble has a name that
you give it as an application developer (e.g. using the <code>@FeignClient</code>
annotation). Spring Cloud creates a new ensemble as an
<code>ApplicationContext</code> on demand for each named client using
<code>RibbonClientConfiguration</code>. This contains (amongst other things) an
<code>ILoadBalancer</code>, a <code>RestClient</code>, and a <code>ServerListFilter</code>.</p>
</div>
<div class="sect2">
<h3 id="_customizing_the_ribbon_client">Customizing the Ribbon Client</h3>
<div class="paragraph">
<p>You can configure some bits of a Ribbon client using external
properties in <code>&lt;client&gt;.ribbon.*</code>, which is no different than using
the Netflix APIs natively, except that you can use Spring Boot
configuration files (example
<a href="#spring-cloud-feign-without-eureka">above</a>). The native options can
be inspected as static fields in <code>CommonClientConfigKey</code> (part of
ribbon-core).</p>
</div>
<div class="paragraph">
<p>Spring Cloud also lets you take full control of the client by
declaring additional configuration (on top of the
<code>RibbonClientConfiguration</code>) using <code>@RibbonClient</code>. Example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlight"><code class="language-java" data-lang="java">@Configuration
@RibbonClient(name = "foo", configuration = FooConfiguration.class)
public class TestConfiguration {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>In this case the client is composed from the components already in
<code>RibbonClientConfiguration</code> together with any in <code>FooConfiguration</code>
(where the latter generally will override the former).</p>
</div>
</div>
<div class="sect2">
<h3 id="_using_the_ribbon_api_directly">Using the Ribbon API Directly</h3>
<div class="paragraph">
<p>You can also use the <code>LoadBalancerClient</code> directly. Example:</p>
</div>
<div class="listingblock">
<div class="content">
@@ -2030,8 +2116,12 @@ public interface StoreClient {
}</code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_spring_resttemplate_as_a_ribbon_client">Spring RestTemplate as a Ribbon Client</h3>
<div class="paragraph">
<p>Indirect usage via <code>RestTemplate</code>.</p>
<p>You can use Ribbon indirectly via an autoconfigured <code>RestTemplate</code>
(provided Spring Cloud and Ribbon are both on the classpath):</p>
</div>
<div class="listingblock">
<div class="content">
@@ -2046,6 +2136,14 @@ public interface StoreClient {
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>The URI is inspected to see if it has a full host name, or a virtual
one. If it is virtual the Ribbon client is used to create a full
physical address. See
<a href="http://github.com/{github-repo}/tree/{github-tag}/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/ribbon/RibbonAutoConfiguration.java">RibbonAutoConfiguration</a>
for details of how the <code>RestTemplate</code> is set up.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
@@ -2862,7 +2960,7 @@ service or the "resource" service if you have one).</p>
</div>
<div id="footer">
<div id="footer-text">
Last updated 2014-12-26 14:06:41 UTC
Last updated 2014-12-26 15:10:13 UTC
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