Features

The component SE Camel embeds the Apache Camel routing engine to execute enterprise integration patterns (EIP) in Petals.

Service Units can be written to describe, for a given provided Petals endpoint, how and where messages should be routed.

Even if it is recommended to route messages toward other Petals services, it is still always possible to exploit Camel transports to integrate with non-Petals external services.

Table of contents

1 Features
2 Introduction

2.1 Overview of a Camel Service Unit

3 Service Unit Content

3.1 A Camel Route
3.2 JBI Descriptor

3.2.1 Interceptor

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Introduction

This implementation of the SE Camel uses Camel version 2.14.X.

Routes can be defined using any of the JVM based DSL, as well as using the XML notation.
For each provides section, one or many routes can be activated when a message is received.
Each route can call any service declared in a consumes section.

The terminology used by Camel is apparently counter-intuitive to the one used in JBI terminology: a camel route consumes a service while an SU provides this same service.
This is because from the route point of view, messages arriving to the provided service are then consumed by the rule.

We show in the next section a general overview of a typical Service Unit.

Overview of a Camel Service Unit

Service Unit Content

A Camel SU typically contains the following elements:

su-camel-ServiceName-provide.zip
   + META-INF
     - jbi.xml
   + service.wsdl (one or several)
   + route-implementation.jar (none, one or several)
   + route-implementation.xml (none, one or several)

There must be at least one route implementation, in a jar file or an xml file ; a WSDL description for every service declared in the JBI descriptor and of course a JBI descriptor.

A Camel Route

Here is an example of a Camel route defined in XML:

    <route id="NormalizeMessageData">
      <from uri="petals:incomingOrders" />
      <convertBodyTo type="java.lang.String" />
      <choice>
        <when>
          <simple>${body} contains '?xml'</simple>
          <unmarshal>
            <jaxb contextPath="org.fusesource.camel" />
          </unmarshal>
          <to uri="petals:orders" />
        </when>
        <otherwise>
          <unmarshal>
            <bindy packages="org.fusesource.camel" type="Csv" />
          </unmarshal>
          <to uri="petals:orders2" />
        </otherwise>
      </choice>     
    </route>

TODO. make that a real example, this is copied from an example on the web...

The only specificity of this route are the URIs used to identify the services consumed by the route (from element) and to which messages are then sent (to element).
The protocol reserved to petals is petals and it is then followed by a unique id from the JBI description as explained next.

JBI Descriptor

The JBI descriptor contains:

The services that are provided by this SU and for which routes will handle messages, and
The services consumed by this SU and that will be callable from the route.

In order to identify a service, each of the, provided or consumed, service must have a unique id.
Of course, a provided service will be only usable by from elements and consumed services by to elements.

<?xml version="1.0" encoding="UTF-8"?>
<jbi:jbi version="1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jbi="http://java.sun.com/xml/ns/jbi"
    xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-5"
    xmlns:helloworld="http://petals.ow2.org/helloworld"
    xmlns:camel="http://petals.ow2.org/components/camel/version-1">

  <jbi:services binding-component="false">
    <jbi:provides
        interface-name="helloworld:Helloworld"
        service-name="helloworld:HelloworldService"
        endpoint-name="HelloworldEndpoint">
      <petalsCDK:wsdl>service.wsdl</petalsCDK:wsdl>
      <camel:service-id>incomingOrders</camel:class>
    </jbi:provides>
    <jbi:consumes
        interface-name="sample:calledInterface1"
        service-name="sample:calledService1"
        endpoint-name="calledEndpoint1">
      <camel:service-id>orders</camel:class>
    </jbi:consumes>
    <jbi:consumes
        interface-name="sample:calledInterface2"
        service-name="sample:calledService2"
        endpoint-name="calledEndpoint2">
      <camel:service-id>orders2</camel:class>
    </jbi:consumes>
    <camel:routes>
      <camel:xml-route>route-implementation.xml</camel:xml-route>
      <camel:jvm-route>org.example.RouteImplementation</camel:jvm-route>
      <camel:jvm-route>org.example.RouteImplementation2</camel:jvm-route>
    </camel:routes>
  </jbi:services>
</jbi:jbi>

TODO. make that a real example, this is copied from jsi181 with bits of EIP and a mock-up for camel:routes...

Configuration of a Service Unit to provide a service (JBI)

Parameter	Description	Default	Required
provides	Describe the JBI service that will be exposed into the JBI bus. Interface (QName), Service (QName) and Endpoint (String) attributes are required.	-	Yes

Configuration of a Service Unit to provide a service (CDK)

Parameter	Description	Default	Required
timeout	Timeout in milliseconds of a synchronous send. This parameter is used by the method `sendSync` (Exchange exchange) proposes by the CDK `Listeners` classes. Set it to 0 for an infinite timeout.	30000	No
exchange-properties	This sections defines the list of properties to set to the JBI exchange when processing a service.	-	No
message-properties	This sections defines the list of properties to set to the JBI message when processing a service.	-	No
validate-wsdl	Activate the validation of the WSDL when deploying a service unit.	true	No
wsdl	Path to the WSDL document describing services and operations exposed by the provided JBI endpoints defined in the SU. The value of this parameter is : an URL a file relative to the root of the SU package If not specified, a basic WSDL description is automaticaly provided by the CDK.	-	No
forward-attachments	Defines if attachment will be forwarded from IN message to OUT message.	false	No
forward-message-properties	Defines if the message properties will be forwarded from IN message to OUT message.	false	No
forward-security-subject	Defines if the security subject will be forwarded from IN message to OUT message.	false	No

Configuration of a Service Unit to provide a service (Camel)

Parameter	Description	Default	Required
service-id	The unique id in the SU for the provided service. It will be visible from the route to refer to this service.	-	Yes

Configuration of a Service Unit to consume a service (JBI)

Parameter	Description	Default	Required
consumes	Refer JBI service to invoke into the JBI bus. You can define an explicit endpoint: interface (QName) / Service (QName) / Endpoint (String) attributes Or define implicit endpoint, to let the container routing according to QOS configurations (HA...): -by Interface attribute (QName); -by Service attribute (QName).	-	Yes

Configuration of a Service Unit to consume a service (Camel)

Parameter	Description	Default	Required
service-id	The unique id in the SU for the consumed service. It will be visible from the route to refer to this service.	-	Yes

Interceptor

Example of an interceptor configuration:

<?xml version="1.0" encoding="UTF-8"?>
<!--...-->
<petalsCDK:su-interceptors>
  <petalsCDK:send>
    <petalsCDK:interceptor name="myInterceptorName">
      <petalsCDK:param name="myParamName">myParamValue</petalsCDK:param>
      <petalsCDK:param name="myParamName2">myParamValue2</petalsCDK:param>
    </petalsCDK:interceptor>
  </petalsCDK:send>
  <petalsCDK:accept>
    <petalsCDK:interceptor name="myInterceptorName">
      <petalsCDK:param name="myParamName">myParamValue</petalsCDK:param>
    </petalsCDK:interceptor>
  </petalsCDK:accept>
  <petalsCDK:send-response>
    <petalsCDK:Interceptor name="myInterceptorName">
      <petalsCDK:param name="myParamName">myParamValue</petalsCDK:param>
    </petalsCDK:Interceptor>
  </petalsCDK:send-response>
  <petalsCDK:accept-response>
    <petalsCDK:Interceptor name="myInterceptorName">
      <petalsCDK:param name="myParamName">myParamValue</petalsCDK:param>
    </petalsCDK:Interceptor>
  </petalsCDK:accept-response>
</petalsCDK:su-interceptors>
<!--...-->

Interceptors configuration for SU (CDK)

Parameter	Description	Default	Required
send	Interceptor dedicated to send phase, for an exchange sent by a consumer	-	No
accept	Interceptor dedicated to receive phase, for an exchange received by a provider	-	No
send-response	Interceptor dedicated to send phase, for an exchange (a response) received by a consumer	-	No
accept-response	Interceptor dedicated to receive phase, for an exchange sent (a response) by a provider	-	No
interceptor - name	Logical name of the interceptor instance. It can be referenced to add extended parameters by a SU Interceptor configuration.	-	Yes
param[] - name	The name of the parameter to use for the interceptor for this SU	-	No
param[]	The value of the parameter to use for the interceptor for this SU	-	No

Wiki

All versions of Petals ESB

Helpful links

Petals-SE-Camel 1.0.0-SNAPSHOT