Petals Documentation > Petals ESB > Petals Components > Components User Guide > Petals-BC-JMS > Petals-BC-JMS 3.0

Petals-BC-JMS 3.0

Features

The Petals JMS component can be used to interact with an external JMS application or server (through a queue or a topic).
When used with the provider role, it allows to post TextMessages to a JMS queue or topic.
When used with the consumer role, it allows to read messages from a queue or receive messages posted on a given topic.
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Recommended Usage

This component should be used whenever interactions with a JMS server or application is required.
This component needs a driver (also called a shared library in Petals) so that Petals can interact with the JMS application. This shared library generally contains the JNDI classes, as a JNDI is used to enable communications between both servers.


  • Only JMS TextMessage are recognized by the Petals JMS component.
  • With the version 3.0, only XML messages can be published and received from a JMS application.
  • In Petals, the invoked service operation is mapped to the operation property of the JMS TextMessage (both in consumming and providing mode).

Sending a message to a JMS Queue

This use case is similar to publishing a message on a JMS topic.

Publishing a message to a JMS Topic

Usage

To do that with Petals, you have to create a service associated with the Petals JMS component.
This is achieved by creating a service unit whose jbi.xml contains a provides section. When deployed in Petals, the Petals JMS component will emulate a service. When this service is invoked, the received message will be posted as a TextMessage on the topic defined in the service unit configuration.

  • All the MEP are allowed. However, due to the JMS paradigm, all exchanges are processed like InOnly exchanges. For exemple, an InOut exchange returns a default message if the JMS message is sent succesfully.
  • The external Queue or Topic referenced by the Service Unit does not have to be available before the Service Unit is started. But the JNDI server where Queue or Topic are registered must be available before the Service Unit deployment.
  • Properties from the Petals message are automatically converted to JMS message properties.

Configuration

Service Unit descriptor

The Service Unit descriptor file ( jbi.xml ) looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<!-- 
	JBI descriptor for the Petals' "petals-bc-jms" component (JMS).
	Originally created for the version 3.1 of the component.
 -->
<jbi:jbi version="1.0" 
	xmlns:generatedNs="http://petals.ow2.org"
	xmlns:jbi="http://java.sun.com/xml/ns/jbi"
	xmlns:jms="http://petals.ow2.org/components/jms/version-3"
	xmlns:petalsCDK="http://petals.ow2.org/components/extensions/version-5"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	
	<!-- Import a Service into Petals or Expose a Petals Service => use a BC. -->
	<jbi:services binding-component="true">
	
		<!-- Import a Service into Petals => provides a Service. -->
		<jbi:provides 		
			interface-name="generatedNs:itf"
			service-name="generatedNs:srv"
			endpoint-name="srvEndpoint">
	
			<!-- CDK specific elements -->
			<petalsCDK:timeout>30000</petalsCDK:timeout>
			<petalsCDK:validate-wsdl>true</petalsCDK:validate-wsdl>
			<petalsCDK:forward-security-subject>false</petalsCDK:forward-security-subject>
			<petalsCDK:forward-message-properties>false</petalsCDK:forward-message-properties>
			<petalsCDK:forward-attachments>false</petalsCDK:forward-attachments>
			<petalsCDK:wsdl xsi:nil="true" />
		
			<!-- Component specific elements -->	
			<jms:jndi-provider-url>tcp://localhost:61616</jms:jndi-provider-url>
			<jms:jndi-initial-context-factory>org.apache.activemq.jndi.ActiveMQInitialContextFactory</jms:jndi-initial-context-factory>
			<jms:jndi-destination-name>dynamicQueues/PetalsQueue</jms:jndi-destination-name>
			<jms:jndi-connection-factory>QueueConnectionFactory</jms:jndi-connection-factory>
			<jms:transacted>false</jms:transacted>
			<jms:max-active>10</jms:max-active>
			<jms:max-idle>5</jms:max-idle>
			<jms:max-wait>10000</jms:max-wait>
			<jms:time-between-eviction-runs-millis>30000</jms:time-between-eviction-runs-millis>
			<jms:min-evictable-idle-time-millis>600000</jms:min-evictable-idle-time-millis>
			<jms:test-while-idle>true</jms:test-while-idle>			
		</jbi:provides>
	</jbi:services>
</jbi:jbi>


Service Unit attributes to provide services

Parameter Description Default Required
provides Name of the JBI service that will be activated to expose the JMS destination into the JBI environment. Interface (qname), service (qname) and endpoint (string) name are required. - Yes
address Address composed of the URL provider (JNDI access) - Yes
destination-name The JMS destination name where messages will be sent (Queue or Topic JNDI name) - Yes
initial-context-factory The initial-context-factory class name, used to create an InitalContext. - Yes
connection-factory name of the JMS ConnectionFactory registered. - Yes
user User name to access the JMS Destination. "" Yes
password Password to access the JMS Destination. "" Yes
transacted JMS communication transacted mode. true or false. "false" Yes
max-active Controls the maximum number of JMS connections that can be borrowed from the pool at one time. When non-positive, there is no limit to the number of connections that may be active at one time. When maxActive is exceeded, the pool is said to be exhausted. "10" No
max-idle Controls the maximum number of JMS connections that can sit idle in the pool at any time. When negative, there is no limit to the number of connections that may be idle at one time. "5" No
max-wait If a positive maxWait value is supplied, the JMS component will wait for at most that many milliseconds to retrieve an available JMS connection. If maxWait is non-positive, the component will wait indefinitely. "10000" No
time-between-eviction-runs-millis Indicates how long the eviction thread should sleep before "runs" of examining idle connections. When non-positive, no eviction thread will
be launched. 		"10000" No
min-evictable-idle-time-millis Specifies the minimum amount of time that a connection may sit idle in the pool before it is eligable for eviction due to idle time. When non-positive,
no connections will be dropped from the pool due to idle time alone. 		"2000" No
test-while-idle Indicates whether or not idle connections should be validated. Connections that fail to validate will be dropped from the pool. "true" No

Advanced configuration of Service Unit (provides elements)

Parameter Description Default Required
wsdl Path to a wsdl file describing services and operations offered by an endpoint activated by the SU. This extension is only usable with provides fields.
The path can be a url "http" or "file" or relative to the r oot directory of the SU archive. Ex: "file:///user/ofabre/test.wsdl" or "/WSDL/test.wsdl".
If no wsdl path is specified, a simplified description will automaticaly be written by the CF. 		- No

Interceptors configuration in the Service Unit

Parameter Description Default Required
name Name of the interceptor to use. That's the name defined in the component - Yes

Service Unit content

The Service Unit has to contain the following elements, packaged in an archive:

  • The META-INF/jbi.xml descriptor file, has described above
  • An optional WSDL file describing the related service.
service-unit.zip
+ META-INF
    - jbi.xml (as defined above)
    - service.wsdl (optional)

Consuming a JBI message from a JMS Queue

This use case is similar to subscribing to a JMS topic.

Subscribing to a JMS Topic

Consumes a JBI service on JMS message

Usage

The Petals JMS component can listen to an external JMS Queue or JMS Topic.
When it receives a message, it creates a Petals message and sends to a Petals service (we say that the component consumes the JBI service). This service is specified in the Service Unit.

  • All MessageExchange patterns are allowed. But, due to the JMS paradigm, all exchanges are processed like InOnly exchanges.
  • The external Queue or Topic referenced by the Service Unit has to be available before you start the Service Unit.

Service Unit Descriptor

The Service Unit descriptor file ( jbi.xml ) looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<jbi:jbi xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:petals="http://petals.objectweb.org/extensions"
 xmlns:jbi="http://java.sun.com/xml/ns/jbi" version="1.0">
 <jbi:services binding-component="false">
  <jbi:consumes interface-name="{http://petals.objectweb.org}HelloworldInterface">
   <petals:params>
    <petals:param name="address">scn://localhost:26400</petals:param>
    <petals:param name="destination-name">queueConsumer</petals:param>
    <petals:param
 name="initial-context-factory">fr.dyade.aaa.jndi2.client.NamingContextFactory</petals:param>
    <petals:param name="connection-factory">qcf</petals:param>
    <petals:param name="user">anonymous</petals:param>
    <petals:param name="password">anonymous</petals:param>
    <petals:param name="transacted">false</petals:param>
    <petals:param name="operation">printMessage</petals:param>
   </petals:params>
  </jbi:consumes>
 </jbi:services>
</jbi:jbi>

JMS communication attributes:

JMS communication attributes:

Service Unit attributes to provide services

Parameter Description Default Required
consumes Name of the JBI service that will be called into the JBI environment. When a JMS message is received. Only the interface (qname) name can be provided (the container will choose a ServiceEndpoint for this interface), or you can only set service (qname) and endpoint (string) names, without the interface name. - Yes
address Address composed of the URL provider (JNDI access) and the destination name to listen to - Yes
destination-name The JMS destination name where messages will be sent (Queue or Topic JNDI name) - Yes
initial-context-factory The initial-context-factory class name, used to create an InitalContext. - Yes
connection-factory name of the JMS ConnectionFactory registered. - Yes
user User name to access the JMS Destination. "" Yes
password Password to access the JMS Destination. "" Yes
transacted JMS communication transacted mode. true or false. "false" No
operation JMS operation property. - Yes

Extra attributes:

Advanced configuration of Service Unit (consumes elements)

Parameter Description Default Required
mep Message exchange pattern abbreviation. This parameter can be used in conjunction with a method of the Listeners: createMessageExchange(Extensions extensions). This method returns
a MessageExchange corresponding to the type of the specified pattern.
Admitted values are: InOnly, RobustInOnly, InOptionalOut, InOut. 		- Yes
operation Operation to call on a service. This parameter can be used in conjuntcion
with the sendXXX methods of the Listeners. If no operation is specified in the MessageExchange to send, this parameter will be used. 		- Yes
timeout Timeout in milliseconds in a synchroneous send. This parameter can be used in conjunction with the sendSync(MessageExchange exchange) method of the Listeners. With this, a synchroneous send is done with this timeout value.
0 for no timeout.
int number >= 0 for a timeout. 		- No
org.objectweb.petals.routing.strategy This property defines the routing strategy. Two kind of strategies can be defined: highest or random. The others parameters represents respectively the local ponderation, the ponderation of the remote active endpoint and
the ponderation of the remote inactive endpoint.
The 'random' strategy chooses an endpoint in function of defined ponderations. The endpoints that have the strongest ponderation can be more easely choose in comparison with the others.
The 'highest' strategy chooses the first endpoint in the list that have the
strongest ponderation. 		- No
org.objectweb.petals.transport.compress The payload of a MessageExchange is an XML file. It can be interesting to compress it before messages are exchanged between two PEtALS nodes.
Values are true or false. True activates the compression of the message content. 		- No
org.objectweb.petals.messaging.noack All JBI exchanges end by a message containing a DONE or ERROR status. The consumer must accept those messages, otherwise they are accumulated in the NMR. Moreover, thoses messages cause useless trafic.
Values are true or false. True make DONE or ERROR messages not sent.
- No
org.objectweb.petals.transport.qos This property sets up the policy of the Quality of Service supported by Petals Transporter.
Possible values are: reliable, fast. If not specified, the reliable policy is selected by default. 		"reliable" No
operation JMS operation property. - Yes

Interceptors configuration in the Service Unit

Parameter Description Default Required
name Name of the interceptor to use, defined in the component. - Yes

Service Unit content

The Service Unit has to contain the following elements, packaged in an archive:

  • The META-INF/jbi.xml descriptor file, has described above 
    service-unit.zip
+ META-INF
    - jbi.xml (as defined above)

Component Configuration

The following attributes can be set during the installation phase to configure the component, using the params element of the jbi-install-component ANT task:
no configuration for this component (JBI).

Configuration of the component (CDK)

Parameter Description Default Required
pool-size Number of threads listening to messages coming from the JBI container 0
(JBIListeners).
Int number >= 1 		0 No
ignored-status When the component receives an acknowledgement message exchange, it can skip the processing of these message according to the type of the acknowledgment. If you decide to not ignore some acknowledgement, the component listeners must take care of them.

Accepted values : DONE_AND_ERROR_IGNORED, DONE_IGNORED, ERROR_IGNORED or NOTHING_IGNORED 		DONE_AND_ERROR_IGNORED No
properties-file Name of the file containing properties used as reference by other parameters. Parameters reference the property name in the following pattern ${myPropertyName}. At runtime, the expression is replaced by the value of the property.

The value of this parameter is :
  • an URL
  • a file relative to the PEtALS installation path
  • an empty value to stipulate a non-using file
 - No Installation
external-listener-class-name Qualified name of the class extending AbstractExternalListener
Only for Binding Components

 - No
jbi-listener-class-name Qualified name of the class extending AbstractJBIListener - Yes
external-listener-class-name Qualified name of the class extending AbstractExternalListener - No

Interceptors configuration in the component

Parameter Description Default Required
class Name of the interceptor class. This class must extend the abstract class org.objectweb.petals.component.common.interceptor.Interceptor. This class have to be present in the classloader, in component or CF or in a shared library. - Yes
name Name of the interceptor. This name will be used for additional class name
configuration in the SU. 		class name No
active Interceptor is active for all SU true No

Samples

Two usecases are defined in this section:

  • The send of JMS Messages to the JBI Helloworld Service Engine.
  • The send of JBI Messages to the JMS External provider.

This section presents how to install the different components and service assemblies to realize these use cases.
In each case, the external JMS Server where the client and provider queue are defined must be started in first.

Install the External JMS Server

To install the external JMS server, you must download and extracts the zip archive at this url:
[Specify joram client link here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/usecase/jms/petals-jms-client/1.0-SNAPSHOT/petals-jms-client-1.0-SNAPSHOT-with-dependencies.zip].
This package also contains the external jms Client and Provider used in the next sections.
Insert all jars in your classpath and start the JMS server with the command below:

java org.objectweb.petals.usecase.jms.common.JMSServer

If it is OK, you must see the lines below:

Start JORAM server S0...
...JORAM server S0 started
     (connected)
Initialize JMS service...
     (connect to JORAM server)
     (Creation of the queue: queueConsumer)
     (Queue created)
     (Queue bound)
     (Creation of the queue: queueProvider)
     (Queue created)
     (Queue bound)
     (disconnect from JORAM server)
JMS destinations initialized...

Now, the external JMS Server is ready and the client and provider queues (respectively, queueConsumer and queueProvider) have been created. You can execute the usecases below.

Send a JMS Message to the JBI Helloworld Service Engine

To send a JMS Message to the JBi HelloWorld Service Engine, you must install several components in the order listed below:

  1. The HelloWorld Service Engine component ([Download here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/petals-se-helloworld/1.4-SNAPSHOT/petals-se-helloworld-1.4-SNAPSHOT.zip]).
  2. The JMS binding component ([Download here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/petals-bc-jms/1.3-SNAPSHOT/petals-bc-jms-1.3-SNAPSHOT.zip]).
  3. The sa-jms-consume service assembly ([Download here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/usecase/jms/sa-jms-consume/1.0-SNAPSHOT/sa-jms-consume-1.0-SNAPSHOT.zip]). This service assembly contains one service unit:
    su-jms-consume service unit. This service unit consumes the endpoint defined by the next service unit.
    Once these components are installed, you must install the JMS client.
    To install the JMS client, you must download and extracts the zip archive at this url:
    [Specify joram client link here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/usecase/jms/petals-jms-client/1.0-SNAPSHOT/petals-jms-client-1.0-SNAPSHOT-with-dependencies.zip]

By default, the JMS client is started in console mode.
Inserts all jars in your classpath and start the JMS client with the command below:

java org.objectweb.petals.usecase.jms.client.Client

If it is OK, you must see the lines below:

Start the Echo JMS client...
-------------------------------
The parameters used for this client are listed below:
           -user=anonymous
           -password=anonymous
           -connection-factory=qcf
           -queue-name=queueConsumer
           -file=null
No file has been given in input:
You can write the xml message to send in the console or write 'quit' to exit ...(for instance:
 <text>hello world</text>)
=>

You can write an xml message and verify that it has been received by the helloworld component.
If you want that the JMS client send a xml file to the helloworld, you can configure it with the 'file' option as seen below:

java org.objectweb.petals.usecase.jms.common.Client -file=test.xml

the test.xml file is shown below:

<jms>
    <text>Hello World</text>
</jms>

All these components can be seen on Figure 3.1, “The sa-jms-consume use case”

Sa-jms-consumes mechanics

Send a JBI Message to the external JMS provider

To send a JBI Message to the external JMS provider, you must install several components in the order listed below:

  • The Sample Client Service Engine component (Download here).
  • The JMS binding component ([Download here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/petals-bc-jms/1.3-SNAPSHOT/petals-bc-jms-1.3-SNAPSHOT.zip]).
  • The sa-jms-provide service assembly ([Download here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/usecase/jms/sa-jms-provide/1.0-SNAPSHOT/sa-jms-provide-1.0-SNAPSHOT.zip]). This service assembly contains one service unit:
    the su-jms-provide service unit. This service unit provides an endpoint to contact the external JMS provider.
    Once these components are installed, you must install the JMS provider.
    To install the JMS provider, you must download and extracts the zip archive at this url:
    [Specify joram client link here|petalsesb:maven.objectweb.org/maven2/org/objectweb/petals/usecase/jms/petals-jms-client/1.0-SNAPSHOT/petals-jms-client-1.0-SNAPSHOT-with-dependencies.zip]

Inserts all jars in your classpath and start the JMS provider with the command below:

java org.objectweb.petals.usecase.jms.provider.Provider

If it is OK, you must see the lines below:

Start the JMS Echo services...
-------------------------------
The parameters used for this server are listed below:
           -user=anonymous
           -password=anonymous
           -connection-factory=qcf
           -queue-name=queueProvider
Start the message receiver...
Message receiver started...
... JMS Echo services started...
Creating message receiver...
MsgListener ready to listen for Receiver

Now, the external JMS provider is ready to receive messages. You can use the sample client to send xml message to the endpoint defined by the su-jms-provide service unit.
All these components can be seen on figure below, “The sa-jms-provide usecase”.

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