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Creating a service-unit for a process definition
Creating the service contract
The SE Activity provides a service with several operation for a process definition. A WSDL is associated to this service. This WSDL can 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 binding section 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
The mapping between operations of the WSDL and operations supported by the SE Activity is declared using a dedicated binding. The binding "Activity" is done adding the element {{
Unknown macro: {http}
operation}} to the element operation of the binding. Its attribute activityAction defines the operation that will be executed.
In the same way, parameters of operations are mapped through an annotation placed inside the message of the binding operation. This annotation is done adding the element {{
Unknown macro: {http}
parameter}} to the input and output messages. This annotation takes two attributes:
- the attribute activityParamName defines the variable name used in the process definition,
- the attribute activityParamValue defines the value to set to the variable using an XPath expression.
Unknown macro: {colore}
What about fault ?
h4. Create an instance of a process definition
h5. Operation
The operation creating instances of process definition is identified by the value createProcInstOp set on the attribute activityAction:
<wsdl:binding name="Order">
<wsdl:operation name="newOrder" type="...">
<activity:operation xmlns:psa="http://petals.ow2.org/se/activity/1.0"
activityAction="createProcInstOp" />
<wsdl:input/>
<wsdl:output/>
</wsdl:operation>
</wsdl:binding>
It is possible to map several operations of the WSDL to the creation of process instances, but its has perhaps no sens.
h5. Input parameters
TODO. Les types ?; les arborescences
Output parameters
*TODO
Complete task of a process instance
Operation
The operation completing a task of a process instance is identified by the value completeTaskOp set on the attribute activityAction:
<wsdl:binding name="Order"> <wsdl:operation name="validOrder" type="..."> <activity:operation xmlns:psa="http://petals.ow2.org/se/activity/1.0" activityAction="completeTaskOp" /> <wsdl:input/> <wsdl:output/> </wsdl:operation> </wsdl:binding>
It is possible to map several operations of the WSDL to complete tasks, for example when a process can have several task in progress concurrently.
Some parameters are expected for this operation:
- identifier of the process instance,
- identifier of the task to complete,
- completion status.
Mapping des parametres à faire
Input parameters
TODO. Les types ?; les arborescences
Output parameters
*TODO
Retrieve process instances
Operation
The operation retrieving process instances is identified by the value retrieveProcInst set on the attribute activityAction:
<wsdl:binding name="Order"> <wsdl:operation name="searchOrder" type="..."> <activity:operation xmlns:psa="http://petals.ow2.org/se/activity/1.0" activityAction="retrieveProcInst" /> <wsdl:input/> <wsdl:output/> </wsdl:operation> </wsdl:binding>
It is possible to map several operations of the WSDL to search process instance, for example with different search criteria.
Input parameters
TODO. Les types ?; les arborescences
Output parameters
*TODO
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 :
|
-
|
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
|
Logging
To enable traces of the Activity engine, you add in the logging configuration file of Petals ESB the following logger with the right level: xxxx
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:
|
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:
|
n-tuple value containing, in millisecond:
|
no |
| ServiceProviderInvokationsResponseTimeRel | The aggregated response times of the service provider invokations on the last sample, grouped by:
|
n-tuple value containing, in millisecond:
|
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 |
|
| No more thread is available in the message exchange acceptor thread pool |
|
| No more message exchange processor is available in the message exchange processor pool |
|
| No more thread is available to run a message exchange processor |
|
Dedicated alerts
No dedicated alert is available.