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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.
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| If you use ActiveMQ as a JMS server, be careful. ActiveMQ (AMQ) does not provide a complete JNDI server, which results in limitations with Petals.
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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.
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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 |
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 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.
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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"> <!-- Expose a Petals Service => consumes a Service. --> <jbi:consumes interface-name="generatedNs:itf" service-name="generatedNs:srv" endpoint-name="srvEndpoint"> <!-- CDK specific elements --> <petalsCDK:timeout>30000</petalsCDK:timeout> <petalsCDK:operation xmlns:wedontcareNs="http://something">wedontcareNs:wedontcare</petalsCDK:operation> <petalsCDK:mep>InOnly</petalsCDK:mep> <!-- 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>dynamicTopics/PetalsTopic</jms:jndi-destination-name> <jms:jndi-connection-factory>ConnectionFactory</jms:jndi-connection-factory> <jms:transacted>false</jms:transacted> </jbi:consumes> </jbi:services> </jbi:jbi>
Service Unit attributes to consume 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 |
| operation | JMS operation property. | - | 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
Configuration of the component, CDK part
| Parameter | Description | Default | Scope |
|---|---|---|---|
| acceptor-pool-size | The size of the thread pool used to accept Message Exchanges from the NMR. Once a message is accepted, its processing is delegated to the processor pool thread. | 1 |
Runtime |
| acceptor-retry-number | Number of tries to submit a message exchange to a processor for processing before to declare that it cannot be processed. | 40 |
Installation |
| acceptor-retry-wait | Base duration, in milliseconds, to wait between two processing submission tries. At each try, the new duration is the previous one plus this base duration. | 250 |
Installation |
| acceptor-stop-max-wait | The max duration (in milliseconds) before, on component stop, each acceptor is stopped by force. | 500 |
Runtime |
| processor-pool-size | The size of the thread pool used to process Message Exchanges. Once a message is accepted, its processing is delegated to one of the thread of this pool. | 10 | Runtime |
| processor-max-pool-size | The maximum size of the thread pool used to process Message Exchanges. The difference between this size and the processor-pool-size represents the dynamic threads that can be created and destroyed during overhead processing time. |
50 |
Runtime |
| processor-keep-alive-time | When the number of processors is greater than the core, this is the maximum time that excess idle processors will wait for new tasks before terminating, in seconds. |
300 |
Runtime |
| processor-stop-max-wait | The max duration (in milliseconds) of message exchange processing on stop phase (for all processors). |
15000 |
Runtime |
| time-beetween-async-cleaner-runs | The time (in milliseconds) between two runs of the asynchronous message exchange cleaner. |
2000 |
Installation |
| properties-file | Name of the file containing properties used as reference by other parameters. Parameters reference the property name using a placeholder in the following pattern ${myPropertyName}. At runtime, the expression is replaced by the value of the property. The properties file can be reloaded using the JMX API of the component. The runtime configuration MBean provides an operation to reload these place holders. Check the service unit parameters that support this reloading. The value of this parameter is :
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- | Installation |
| monitoring-sampling-period | Period, in seconds, of a sample used by response time probes of the monitoring feature. |
300 |
Installation |
Definition of CDK parameter scope :
- Installation: The parameter can be set during the installation of the component, by using the installation MBean (see JBI specifications for details about the installation sequence). If the parameter is optional and has not been defined during the development of the component, it is not available at installation time.
- Runtime: The paramater can be set during the installation of the component and during runtime. The runtime configuration can be changed using the CDK custom MBean named RuntimeConfiguration. If the parameter is optional and has not been defined during the development of the component, it is not available at installation and runtime times.
Interceptor
Interceptors can be defined to inject some post or pre processing in the component during service processing.
Using interceptor is very sensitive and must be manipulate only by power users. An non properly coded interceptor engaged in a component can lead to uncontrolled behaviors, out of the standard process.
Example of an interceptor configuration:
<?xml version="1.0" encoding="UTF-8"?> <!--...--> <petalsCDK:component-interceptors> <petalsCDK:interceptor active="true" class="org.ow2.petals.myInterceptor" name="myInterceptorName"> <petalsCDK:param name="myParamName">myParamValue</petalsCDK:param> <petalsCDK:param name="myParamName2">myParamValue2</petalsCDK:param> </petalsCDK:interceptor> </petalsCDK:component-interceptors> <!--...-->
Interceptors configuration for Component (CDK)
| Parameter | Description | Default | Required |
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| interceptor - class | Name of the interceptor class to implement. This class must extend the abstract class org.ow2.petals.component.common.interceptor.Interceptor. This class must be loadable from the component classloader, or in a dependent Shared Library classloader. | - | Yes |
| interceptor - name | Logical name of the interceptor instance. It can be referenced to add extended parameters by a SU Interceptor configuration. | - | Yes |
| interceptor - active | If true, the Interceptor instance is activated for every SU deployed on the component. If false, the Interceptor can be activated: -by the InterceptorManager Mbean at runtime, to activate the interceptor for every deployed SU. -by a SU configuration |
- | Yes |
| param[] - name | The name of the parameter to use for the interceptor. | - | No |
| param[] | The value of the parameter to use for the interceptor. | - | No |
Monitoring the component
Using metrics
Several probes providing metrics are included in the component, and are available through the JMX MBean 'org.ow2.petals:type=custom,name=monitoring_<component-id>', where <component-id> is the unique JBI identifier of the component.
Common metrics
The following metrics are provided through the Petals CDK, and are common to all components:
| Metrics, as MBean attribute | Description | Detail of the value | Configurable |
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| MessageExchangeAcceptorThreadPoolMaxSize | The maximum number of threads of the message exchange acceptor thread pool | integer value, since the last startup of the component | yes, through acceptor-pool-size |
| MessageExchangeAcceptorThreadPoolCurrentSize | The current number of threads of the message exchange acceptor thread pool. Should be always equals to MessageExchangeAcceptorThreadPoolMaxSize. | instant integer value | no |
| MessageExchangeAcceptorCurrentWorking | The current number of working message exchange acceptors. | instant long value | no |
| MessageExchangeAcceptorMaxWorking | The max number of working message exchange acceptors. | long value, since the last startup of the component | no |
| MessageExchangeAcceptorAbsoluteDurations | The aggregated durations of the working message exchange acceptors since the last startup of the component. | n-tuple value containing, in nanosecond:
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no |
| MessageExchangeAcceptorRelativeDurations | The aggregated durations of the working message exchange acceptors on the last sample. | n-tuple value containing, in nanosecond:
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no |
| MessageExchangeProcessorAbsoluteDurations | The aggregated durations of the working message exchange processor since the last startup of the component. | n-tuple value containing, in milliseconds:
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no |
| MessageExchangeProcessorRelativeDurations | The aggregated durations of the working message exchange processor on the last sample. | n-tuple value containing, in milliseconds:
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no |
| MessageExchangeProcessorThreadPoolActiveThreadsCurrent | The current number of active threads of the message exchange processor thread pool | instant integer value | no |
| MessageExchangeProcessorThreadPoolActiveThreadsMax | The maximum number of threads of the message exchange processor thread pool that was active | integer value, since the last startup of the component | no |
| MessageExchangeProcessorThreadPoolIdleThreadsCurrent | The current number of idle threads of the message exchange processor thread pool | instant integer value | no |
| MessageExchangeProcessorThreadPoolIdleThreadsMax | The maximum number of threads of the message exchange processor thread pool that was idle | integer value, since the last startup of the component | no |
| MessageExchangeProcessorThreadPoolMaxSize | The maximum size, in threads, of the message exchange processor thread pool | instant integer value | yes, through http-thread-pool-size-max |
| MessageExchangeProcessorThreadPoolMinSize | The minimum size, in threads, of the message exchange processor thread pool | instant integer value | yes, through http-thread-pool-size-min |
| MessageExchangeProcessorThreadPoolQueuedRequestsCurrent | The current number of enqueued requests waiting to be processed by the message exchange processor thread pool | instant integer value | no |
| MessageExchangeProcessorThreadPoolQueuedRequestsMax | The maximum number of enqueued requests waiting to be processed by the message exchange processor thread pool since the last startup of the component | instant integer value | no |
| ServiceProviderInvocations | The number of service provider invocations grouped by:
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integer counter value since the last startup of the component | no |
| ServiceProviderInvocationsResponseTimeAbs | The aggregated response times of the service provider invocations since the last startup of the component grouped by:
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n-tuple value containing, in millisecond:
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no |
| ServiceProviderInvocationsResponseTimeRel | The aggregated response times of the service provider invocations on the last sample, grouped by:
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n-tuple value containing, in millisecond:
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no |
Dedicated metrics
No dedicated metric is available.
Receiving alerts
Several alerts are notified by the component through notification of the JMX MBean 'org.ow2.petals:type=custom,name=monitoring_<component-id>', where <component-id> is the unique JBI identifier of the component.
 | To integrate these alerts with Nagios, see Receiving Petals ESB defects in Nagios. |
Common alerts
| Defect | JMX Notification |
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| A message exchange acceptor thread is dead |
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| No more thread is available in the message exchange acceptor thread pool |
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| No more thread is available to run a message exchange processor |
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Dedicated alerts
No dedicated alert is available.