The SE Activity provides a service with several operation for a process definition. A WSDL is associated to this service. This WSDL wan be written freely. The user can use its own namespace, its own names, ... It is only constraint by the following rules:

the operations of the port type are annotated to link them to the supported operations (create an instance of the process definition, complete the current task of the process instance, ...)
the mandatory parameters of the operation are annotated to retrieve the right values.

Identifying operations

Create an instance of a process definition

Because operation in WSDL 1.1 does not allow attribute extensibility, an operation is annotated by adding an operationAttr element as a child of the operation element. The operation attribute of operationAttr specifies the annotation. The value createProcInstOp identifies the operation creating a new instance of the process definition. An example of such an annotation is shown below.

<wsdl:portType name="Order">
   <wsdl:operation name="newOrder">
      <psa:operationAttr xmlns:psa="http://petals.ow2.org/se/activity/1.0"
         operation="createProcInstOp" />
      <wsdl:input message="NewOrderRequestMessage" />
      <wsdl:output message="NewOrderResponseMessage" />
   </wsdl:operation>
</wsdl:portType>

If several operation are annotated by createProcInstOp, an error is thrown, and the deployment of the service unit is interrupted.

All parameters of the operation are used as parameter to create the instance of the process definition. Peut être ajouter un mapping pour indiquer nom de la variable coté process et type ? Comment gérer les arborescences ?

Complete the current task of a process instance

Because operation in WSDL 1.1 does not allow attribute extensibility, an operation is annotated by adding an operationAttr element as a child of the operation element. The operation attribute of operationAttr specifies the annotation. The value completeTaskOp identifies the operation creating a new instance of the process definition. An example of such an annotation is shown below.

<wsdl:portType name="Order">
   <wsdl:operation name="validOrder">
      <psa:operationAttr xmlns:psa="http://petals.ow2.org/se/activity/1.0"
         operation="completeTaskOp" />
      <wsdl:input message="ValidOrderRequestMessage" />
      <wsdl:output message="ValidOrderResponseMessage" />
   </wsdl:operation>
</wsdl:portType>

If several operation are annotated by completeTaskOp, an error is thrown, and the deployment of the service unit is interrupted.

Some parameters are expected for this operation:

identifier of the process instance,
identifier of the task to complete,
completion status.
These parameters are also annotated into the WSDL, more precisely in the XSD part. Est ce mieux dans le XSD ou dans la definition de l'operation ? Ne serait-il pas mieux d'utiliser l'annotation au niveau de l'operation et de donner les paramètres par une expression XPath ? Même question pour les valeurs OK, KO de completaion de la tache ?

Retrieve process instances

Because operation in WSDL 1.1 does not allow attribute extensibility, an operation is annotated by adding an operationAttr element as a child of the operation element. The operation attribute of operationAttr specifies the annotation. The value retrieveProcInst identifies the operation creating a new instance of the process definition. An example of such an annotation is shown below.

<wsdl:portType name="Order">
   <wsdl:operation name="searchOrder">
      <psa:operationAttr xmlns:psa="http://petals.ow2.org/se/activity/1.0"
         operation="createProcInstOp" />
      <wsdl:input message="SearchOrderRequestMessage" />
      <wsdl:output message="SearchOrderResponseMessage" />
   </wsdl:operation>
</wsdl:portType>

If several operation are annotated by retrieveProcInst, an error is thrown, and the deployment of the service unit is interrupted.

Some search criteria parameters are expected for this operation. These parameters are also annotated into the WSDL, more precisely in the XSD part. Est ce mieux dans le XSD ou dans la definition de l'operation ? Ne serait-il pas mieux d'utiliser l'annotation au niveau de l'operation et de donner les paramètres par une expression XPath ?

Configuring the component

The component is be configured through the parameters of its JBI descriptor file. These parameters are divided in following groups:

JBI parameters that have not to be changed otherwise the component will not work,
CDK parameters that are parameters driving the processing of the CDK layer,
and *Activity parametrs" that are relative to the engine "Activity".

TODO: Mettre une copie en exemple d'un descripteur JBI du SE

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

	<component type="service-engine">
		<identification>
			<name>petals-se-activity</name>
			<description>An Activity Service Engine</description>
		</identification>

		<component-class-name description="Activity Component class">org.ow2.petals.se.activity.ActivitySe</component-class-name>
		<component-class-path><path-element/></component-class-path>
		<bootstrap-class-name>org.ow2.petals.component.framework.DefaultBootstrap</bootstrap-class-name>
		<bootstrap-class-path><path-element/></bootstrap-class-path>

		<petalsCDK:acceptor-pool-size>3</petalsCDK:acceptor-pool-size>
		<petalsCDK:processor-pool-size>10</petalsCDK:processor-pool-size>
		<petalsCDK:processor-max-pool-size>50</petalsCDK:processor-max-pool-size>
		<petalsCDK:properties-file></petalsCDK:properties-file>
		<petalsCDK:jbi-listener-class-name>org.ow2.petals.se.activity.ActivityJBIListener</petalsCDK:jbi-listener-class-name>
	</component>
</jbi>

CDK parameters

The component configuration includes the configuration of the CDK. The following parameters correspond to the CDK configuration.

Configuration of the component, CDK part

Parameter	Description	Default	Required	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.	3	Yes	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	No	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 added by this base duration multiplied by the try number plus a random value between 0 and 10.	250	No	Installation
acceptor-stop-max-wait	The max duration (in milliseconds) of the stop of an acceptor before to force it to stop.	500	No	Runtime
message-processor-max-pool-size	Max size of the object pool containing message exchange processors.	`processor-max-pool-size`	No	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	Yes	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	No	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	No	Runtime
processor-stop-max-wait	The max duration (in milliseconds) of message exchange processing on stop phase.	15000	No	Runtime
time-beetween-async-cleaner-runs	The time (in milliseconds) between two runs of the asynchronous message exchange cleaner.	2000	No	Installation
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
monitoring-sampling-period	Period, in seconds, of a sample used by response time probes of the monitoring feature.	300	No	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
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

Component specific parameters

These parameters are extracted from parameters available for Activity 5.1.3:

database parameters. Your are responsible to provide this database according to your needs. And especially, you must assume that the database is highly available to have a SE Activity highly available.

Database parameters

Configuration of the component, Specific parameter part, Database

Parameter	Description	Default	Required	Scope
jdbc-url	URL of the database. The default database is an in-memory database	jdbc:h2:mem:activiti;DB_CLOSE_DELAY=1000	Yes	Installation
jdbc-driver	JDBC driver. Except for the default JDBC driver, it must be provided as shared-library.	org.h2.Driver	Yes	Installation
jdbc-username	Username used for the database connection.	sa	Yes	Installation
jdbc-password	Passwrd used for the database connection.	""	Yes	Installation
jdbc-max-active-connections	The number of idle connections that the database connection pool at maximum at any time can contain.	10	No	Runtime
jdbc-max-idle-connections	The number of active connections that the database connection pool at maximum at any time can contain.	-	No	Runtime
jdbc-max-checkout-time	The amount of time in milliseconds a connection can be 'checked out' from the connection pool before it is forcefully returned.	20000 (20 seconds)	No	Runtime
jdbc-max-wait-time	This is a low level setting that gives the pool a chance to print a log status and re-attempt the acquisition of a connection in the case that it’s taking unusually long (to avoid failing silently forever if the pool is misconfigured).	20000 (20 seconds)	No	Runtime

Monitoring the component

In this documentation, the term "Allocated threads" must be understood as "Active threads", see PETALSDISTRIB-37. This naming error will be fixed in the next version.

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
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
MessageExchangeProcessorObjectPoolBorrowedObjectsCurrent	The current number of borrowed object of the message exchange processor object pool	instant integer value	no
MessageExchangeProcessorObjectPoolBorrowedObjectsMax	The maximum number of object of the message exchange processor object pool that was borrowed	integer value, since the last startup of the component	no
MessageExchangeProcessorObjectPoolIdleObjectsCurrent	The current number of idel object of the message exchange processor object pool	instant integer value	no
MessageExchangeProcessorObjectPoolIdleObjectsMax	The maximum number of object of the message exchange processor object pool that was idle	integer value, since the last startup of the component	no
MessageExchangeProcessorObjectPoolMaxSize	The maximum size, in objects, of the message exchange processor object pool	instant integer value	yes, through `processor-max-pool-size`
MessageExchangeProcessorObjectPoolMinIdleSize	The minimum size, in objects (in state idle), of the message exchange processor object pool	instant integer value	yes, through `processor-pool-size`
MessageExchangeProcessorObjectPoolExhaustion	The number of message exchange processor object pool exhaustions	integer counter value, since the last startup of the component	no
MessageExchangeProcessorThreadPoolAllocatedThreadsCurrent	The current number of allocated threads of the message exchange processor thread pool	instant integer value	no
MessageExchangeProcessorThreadPoolAllocatedThreadsMax	The maximum number of threads of the message exchange processor thread pool that was allocated	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 that was allocated since the last startup of the component	instant integer value	no
ServiceProviderInvokations	The number of service provider invokations grouped by: interface name, as `QName`, the invoked service provider, service name, as `QName`, the invoked service provider, invoked operation, as `QName`, message exchange pattern, and execution status (PENDING, ERROR, FAULT, SUCCEEDED).	integer counter value since the last startup of the component	no
ServiceProviderInvokationsResponseTimeAbs	The aggregated response times of the service provider invokations since the last startup of the component grouped by: interface name, as `QName`, the invoked service provider, service name, as `QName`, the invoked service provider, invoked operation, as `QName`, message exchange pattern, and execution status (PENDING, ERROR, FAULT, SUCCEEDED).	n-tuple value containing, in millisecond: the maximum response time, the average response time, the minimum response time.	no
ServiceProviderInvokationsResponseTimeRel	The aggregated response times of the service provider invokations on the last sample, grouped by: interface name, as `QName`, the invoked service provider, service name, as `QName`, the invoked service provider, invoked operation, as `QName`, message exchange pattern, and execution status (PENDING, ERROR, FAULT, SUCCEEDED).	n-tuple value containing, in millisecond: the maximum response time, the average response time, the minimum response time, the 10-percentile response time (10% of the response times are lesser than this value), the 50-percentile response time (50% of the response times are lesser than this value), the 90-percentile response time (90% of the response times are upper than this value).	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
A message exchange acceptor thread is dead	`type`: `org.ow2.petals.component.framework.process.message.acceptor.pool.thread.dead` no user data
No more thread is available in the message exchange acceptor thread pool	`type`: `org.ow2.petals.component.framework.process.message.acceptor.pool.exhausted` no user data
No more message exchange processor is available in the message exchange processor pool	`type`: `org.ow2.petals.component.framework.process.message.processor.object.pool.exhausted` no user data
No more thread is available to run a message exchange processor	`type`: `org.ow2.petals.component.framework.process.message.processor.thread.pool.exhausted` no user data

Dedicated alerts

No dedicated alert is available.

Wiki

All versions of Petals ESB

Helpful links

Petals-SE-Activity 1.0.0-SNAPSHOT

Creating a service-unit for a process definition

Creating the service contract