Page History

...

Available as of Camel 2.18

The The serviceCall EIP allows to call remote services in a distributed system. The service to call is looked up in a service registry of some sorts such as Kubernetes, Consul, etcd, zookeeperZookeeper.
The EIP separates the configuration of the service registry from the calling of the service. 

Maven users will need to add the dependency for the service registry supported from the following:

• camel-consul
• camel-etcd
• camel-kubernetes
• camel-ribbon

Each implementation has their own set of configuration.

...

When calling a service you may just refer to the name of the service in the EIP as shown below:

from("direct:start")
    .serviceCall("foo")
    .to("mock:result");

...

Camel will then lookup a service with the name "name foo" from the chosen Camel component that integrates with the service registry. The lookup returns a set of of IP:PORT paris pairs that refer to which a list of active servers that host the remote service. Camel will then pick select a server at random server from the list to use and then build a Camel uri URI with the chosen IP and PORT number.

By default Camel uses the HTTP component, so the example above will resolve into a Camel uri URI that is called by a dynamic to dynamic toD endpoint as shown:

toD("http://IP:PORT")
 
<toD uri="http:IP:port"/>

You can also call the service using URI parameters such as beer=yes:

serviceCall("foo?beer=yes")
 
<serviceCall name="foo?beer=yes")/>

You can also provide a context-path such as shown:

serviceCall("foo/beverage?beer=yes")
 
<serviceCall name="foo/beverage?beer=yes")/>

Service Name to Camel URI Examples

So as you can see above the service name is resolved as a Camel endpoint uriURI, and here is a few more examples (where where -> shows what the resolution of the Camel uri is resolved asURI):

serviceCall("myService") -> http://hostname:port
serviceCall("myService/foo") -> http://hostname:port/foo
serviceCall("http:myService/foo") -> http:hostname:port/foo
 
<serviceCall name="myService"/> -> http://hostname:port
<serviceCall name="myService/foo"/> -> http://hostname:port/foo
<serviceCall name="http:myService/foo"/> -> http:hostname:port/foo

If you want full control of the resolved URI you can provide an additional uri URI parameter where you specify the Camel uri URI as you want. In the uri URI you can use the service name which are then resolved to to IP:PORT as shown:

serviceCall("myService", "http:myService.host:myService.port/foo") -> http:hostname:port/foo
serviceCall("myService", "netty4:tcp:myService?connectTimeout=1000") -> netty:tcp:hostname:port?connectTimeout=1000
 
<serviceCall name="myService" uri="http:myService.host:myService.port/foo"/> -> http:hostname:port/foo
<serviceCall name="myService" uri="netty4:tcp:myService?connectTimeout=1000"/> -> netty:tcp:hostname:port?connectTimeout=1000

In the example above we want to call a service named "named myService" and we can control the resolved URI as in the 2nd second parameter. Notice how in the 1st first example we can use use serviceName.host and and serviceName.port to refer to either the the IP or PORT. If you just use use serviceName then its it's resolved as IP:PORT.

Configuring Service Call

By default Camel will call the service using the HTTP component, but you can configure to use a different component such as HTTP4, Netty4 HTTP as shown:

KubernetesConfigurationDefinition config = new KubernetesConfigurationDefinition();
config.setComponent("netty4-http");
 
// register the service call configuration
context.setServiceCallConfiguration(config);
 
from("direct:start")
    .serviceCall("foo")
    .to("mock:result");

.. and in In XML DSL:

<camelContext xmlns="http://camel.apache.org/schema/spring">
  <kubernetesConfiguration id="kubernetes" component="netty4-http"/>
  <route>
    <from uri="direct:start"/>
    <serviceCall name="foo"/>
    <to uri="mock:result"/>
  </route>
</camelContext>

Common Configuration

These are the common configuration that each implementation is sharing.

Kubernetes Configuration

Ribbon Configuration

Currently no ribbon specific options yet.