Workflows with JMS messaging

 Last several years there is a lot of buzz about Apache Kafka, Apache Pulsar and in general about event streams. But looking into lots of organizations they are in many case still relying on "old good traditional messaging". To give one example of that, IBM MQ is very popular within small, medium and big enterprises to realize messaging between systems.

While event streams are starting to play bigger role in integration, there are still big opportunities to build systems and services based on traditional messaging. In Java world, JMS is an excellent solution to that. Majority (if not all) Java frameworks for building services have support for JMS such as Spring, Quarkus, Jakarta EE application servers and many more.

Have a read of full article here.

jBPM 6 first steps

This post is about to give a very quick introduction to how users can take their first steps in jBPM 6. Using completely web tooling to build up:

• processes
• rules
• process and task forms
• data model

With just three simple examples you will learn how easy and quickly you can start with BPM. So let's start.

The simples process

First process is illustrating how you move around in KIE workbench web application. Where to:

• create repository
• create project
• configure Knowledge Base, KnowledgeSession
• create process
• build and deploy
• execute process and work with user task

Custom data and forms

Next let's explore more and start with bit advanced features like:

• building custom data model that will be used as process variable
• make use of process variables in user task
• define custom forms for process and tasks
• edit and adjust your process and task forms

Make use of business rules and decisions in your process

At the end let's make the process be more efficient by applying business rules in the process and then use gateways as deception points. This example introduces:

• use of business rule task
• define business rules with Drools
• use XOR gateway to split between different paths in the process

Important to note that business rule task can automatically insert and retract process variables using data input and output of business rule task. When defining them make sure that both data input and output are named exactly the same to allow engine to properly retract the facts on business rule task completion.

That would be all for the first steps with jBPM 6. Stay tuned for more examples and videos!

As usual comments more than welcome.

Make your work asynchronous

Asynchronous execution as part of a business process is common requirement. jBPM has had support for it via custom implementation of WorkItemHandler. In general it was as simple as providing async handler (is it as simple as it sounds?) that delegates the actual work to some worker e.g. a separate thread that proceeds with the execution.

Before we dig into details on jBPM v6 support for asynchronous execution let's look at what are the common requirements for such execution:

• first and foremost it allows asynchronous execution of given piece of business logic
• it allows to retry in case of resources are temporarily unavailable e.g. external system interaction
• it allows to handle errors in case all retries has been attempted
• it provides cancelation option
• it provides history log of execution

When confronting these requirements with the "simple async handler" we can directly notice that all of these would need to be implemented all over again by different systems. So that is not so appealing, isn't?

jBPM executor to the rescue 

Since version 6, jBPM introduces new component called jbpm executor which provides quite advanced features for asynchronous execution. It delivers generic environment for background execution of commands. Commands are nothing more than business logic encapsulated with simple interface. It does not have any process runtime related information, that means no need to complete work items, or anything of that sort. It purely focuses on the business logic to be executed. It receives data via CommandContext and returns results of the execution with ExecutionResults. The most important rule for both input and output data is - it must be serializable.

Executor covers all requirements listed above and provides user interface as part of jbpm console and kie workbench (kie-wb) applications.

Illustrates Jobs panel in kie-wb application

Above screenshot illustrates history view of executor's job queue. As can be seen on it there are several options available:

• view details of the job
• cancel given job
• create new job

With that quite few things can already be achieved. But what about executing logic as part of a process instance - via work item handler?

Async work item handler

jBPM (again since version 6) provides an out of the box async work item handler that is backed by the jbpm executor. So by default all features that executor delivers will be available for background execution within process instance. AsyncWorkItemHandler can be configured in two ways:

1. as generic handler that expects to get the command name as part of work item parameters
2. as specific handler for given type of work item - for example web service

Option number 1 is by default configured for jbpm console and kie-wb web applications and is registered under async name in every ksession that is bootstrapped within the applications. So whenever there is a need to execute some logic asynchronously following needs to be done at modeling time (using jbpm web designer):

• specify async as TaskName property 
• create data input called CommandClass
• assign fully qualified class name for the CommandClass data input

Next follow regular way to complete process modeling. Note that all data inputs will be transferred to executor so they must be serializable.

Illustrates assignments for an async node (web service execution)

Second option allows to register different instances of AsyncWorkItemHandler for different work items. Since it's registered for dedicated work item most likely the command will be dedicated to that work item as well. If so CommandClass can be specified on registration time instead of requiring it to be set as work item parameters. To register such handlers for jbpm console or kie-wb additional class is required to inform what shall be registered. A CDI bean that implements WorkItemHandlerProducer interface needs to be provided and placed on the application classpath so CDI container will be able to find it. Then at modeling time TaskName property needs to be aligned with those used at registration time.

Ready to give it a try?

To see this working it's enough to give a try to the latest kie-wb or jbpm console build (either master or CR2). As soon as application is deployed, go to Authoring perspective and you'll find an async-examples project in jbpm-playground repository. It comes with three samples that illustrates asynchronous execution from within process instance:

• async executor
• async data executor
• check weather

Async executor is the simplest execution process that allows execute commands asynchronously. When starting a process instance it will ask for fully qualified class name of the command, for demo purpose use org.jbpm.executor.commands.PrintOutCommand which is similar to the SystemOutWorkItemHandler that simple prints out to logs the content of the CommandContext. You can leave it empty or provide invalid command class name to see the error handling mechanism (using boundary error event).

Async data executor is preatty much same as Async executor but it does operate on custom data (included in the project - User and UserCommand). On start process form use org.jbpm.examples.cmd.UserCommand to invoke custom command included in the project.

Check weather is asynchronous execution of a web service call. It checks weather for any U.S. zip code and provides results as a human task. So on start form specify who should receive user task with results and what is the zip code of the city you would like to get weather forecast for.

Start Check weather process with async web service execution

And that's it, asynchronous execution is now available out of the box in jBPM v6. 

Have fun and as usual keep the comments coming so we can add more useful features!

Clustering in jBPM v6

Clustering in jBPM v5 was not an easy task, there where several known issues that had to be resolved on client (project that was implementing solution with jBPM) side, to name few:

• session management - when to load/dispose knowledge session
• timer management - required to keep knowledge session active to fire timers

This is not the case any more in version 6 where several improvements made their place in code base, for example new module that is responsible for complete session management was introduced - jbpm runtime manager. More on runtime manager in next post, this one focuses on how clustered solution might look like. First of all lets start with all the important pieces jbpm environment consists of:

1. asset repository - VFS based repository backed with GIT - this is where all the assets are stored during authoring phase
2. jbpm server that includes JBoss AS7 with deployed jbpm console (bpm focused web application) of kie-wb (fully features web application that combines BPM and BRM worlds)
3. data base - backend where all the state date is kept (process instances, ksessions, history log, etc)

Repository clustering

Asset repository is GIT backed virtual file system (VFS) that keeps all the assets (process definitions, rules, data model, forms, etc) is reliable and efficient way. Anyone who used to work with GIT understands perfectly how good it is for source management and what else assets are if not source code?

So if that is file system it resides on the same machine as the server that uses it, that enforces it to be kept in sync between all servers of a cluster. For that jbpm makes use of two well know open source projects:

• Apache Zookeeper
• Apache Helix

Zookeeper is responsible for gluing all parts together where Helix is cluster management component that registers all cluster details (cluster itself, nodes, resources).

So this two components are utilized by the runtime environment on which jbpm v6 is based on:

• kie-commons - provides VFS implementation and clustering 
• uber fire framework - provides backbone of the web applications

So let's take a look at what we need to do to setup cluster of our VFS:

Get the software

• download Apache Zookeeper (note that 3.3.4 and 3.3.5 are the only versions that were currently tested so make sure you get the correct version)
• download Apache Helix  (note that version that was tested was 0.6.1)

Install and configure

• unzip Apache Zookeeper into desired location - ( from now one we refer to it as zookeeper_home)
• go to zookeeper_home/conf and make a copy of zoo_sample.conf to zoo.conf
• edit zoo.conf and adjust settings if needed, these two are important in most of the cases:

# the directory where the snapshot is stored.
dataDir=/tmp/zookeeper
# the port at which the clients will connect
clientPort=2181

•  unzip Apache helix to into desired location (from now one we refer to it as helix_home)

Setup cluster

Now we have all the software available locally so next step is to configure the cluster itself. We start with start of the Zookeeper server that will be master of the configuration of the cluster:

• go to zookeeper_home/bin
• execute following command to start zookeeper server:

sudo ./zkServer.sh start

• zookeeper server should be started, if the server fails to start make sure that the data directory defined in zoo.conf file exists and is accessible
• all zookeeper activities can be viewed zookeeper_home/bin/zookeeper.out

To do so, Apache Helix provides utility scripts that can be found in helix_home/bin.

• go to helix_home/bin
• create cluster

./helix-admin.sh --zkSvr localhost:2181 --addCluster jbpm-cluster

• add nodes to the cluster 

node 1

./helix-admin.sh --zkSvr localhost:2181 --addNode jbpm-cluster nodeOne:12345

node2

    ./helix-admin.sh --zkSvr localhost:2181 --addNode jbpm-cluster nodeTwo:12346

add as many nodes as you will have cluster members of jBPM server (in most cases number of application servers in the cluster)

NOTE: nodeOne:12345 is the unique identifier of the node, that will be referenced later on when configuring application severs, although it looks like host and port number it is use to identify uniquely logical node.

• add resources to the cluster

./helix-admin.sh --zkSvr localhost:2181 

           --addResource jbpm-cluster vfs-repo 1 LeaderStandby AUTO_REBALANCE

• rebalance cluster to initialize it

./helix-admin.sh --zkSvr localhost:2181 --rebalance jbpm-cluster vfs-repo 2

• start the Helix controller to manage the cluster

./run-helix-controller.sh --zkSvr localhost:2181 

                        --cluster jbpm-cluster 2>&1 > /tmp/controller.log &

Values given above are just examples and can be changed according to the needs:

cluster name: jbpm-cluster

node name: nodeOne:12345, nodeTwo:12346

resource name: vfs-repo

zkSvr value must match Zookeeper server that is used.

Prepare data base 

Before we start with application server configuration data base needs to be prepared, for this example we use PostgreSQL data base. jBPM server will create all required tables itself by default so there is no big work required for this but some simple tasks must be done before starting the server configuration.

Create data base user and data base

First of all PostgreSQL data base needs to be installed, next user needs to be created on the data base that will own the jbpm schema, in this example we use:

user name: jbpm

password: jbpm

Once the user is ready, data base can be created, and again for the example jbpm is chosen for the data base name.

NOTE: this information (username, password, data base name) will be used later on in application server configuration.

Create Quartz tables

Lastly Quartz related tables must be created, to do so best is to utilize the data base scripts provided with Quartz distribution, jbpm uses Quartz 1.8.5. DB scripts are usually located under QUARTZ_HOME/docs/dbTables.

Create quartz definition file 

Quartz configuration that will be used by the jbpm server needs to accomodate the needs of the environment, as this guide is about to show the basic setup obviously it will not cover all the needs but will allow for further improvements.

Here is a sample configuration used in this setup:

#============================================================================

# Configure Main Scheduler Properties  

#============================================================================

org.quartz.scheduler.instanceName = jBPMClusteredScheduler

org.quartz.scheduler.instanceId = AUTO

#============================================================================

# Configure ThreadPool  

#============================================================================

org.quartz.threadPool.class = org.quartz.simpl.SimpleThreadPool

org.quartz.threadPool.threadCount = 5

org.quartz.threadPool.threadPriority = 5

#============================================================================

# Configure JobStore  

#============================================================================

org.quartz.jobStore.misfireThreshold = 60000

org.quartz.jobStore.class=org.quartz.impl.jdbcjobstore.JobStoreCMT

org.quartz.jobStore.driverDelegateClass=org.quartz.impl.jdbcjobstore.PostgreSQLDelegate

org.quartz.jobStore.useProperties=false

org.quartz.jobStore.dataSource=managedDS

org.quartz.jobStore.nonManagedTXDataSource=notManagedDS

org.quartz.jobStore.tablePrefix=QRTZ_

org.quartz.jobStore.isClustered=true

org.quartz.jobStore.clusterCheckinInterval = 20000

#============================================================================

# Configure Datasources  

#============================================================================

org.quartz.dataSource.managedDS.jndiURL=jboss/datasources/psjbpmDS

org.quartz.dataSource.notManagedDS.jndiURL=jboss/datasources/quartzNotManagedDS

Configure JBoss AS 7 domain

1. Create JDBC driver module - for this example PostgreSQL

a) go to JBOSS_HOME/modules directory (on EAP JBOSS_HOME/modules/system/layers/base)

b) create module folder org/postgresql/main

c) copy postgresql driver jar into the module folder (org/postgresql/main) as postgresql-jdbc.jar          name

d) create module.xml file inside module folder (org/postgresql/main) with following content:

         <module xmlns="urn:jboss:module:1.0" name="org.postgresql">

         <resources>

           <resource-root path="postgresql-jdbc.jar"/>

         </resources>

             <dependencies>

      <module name="javax.api"/>

      <module name="javax.transaction.api"/>

         </dependencies>

</module>

2. Configure data sources for jbpm server

a) go to JBOSS_HOME/domain/configuration

b) edit domain.xml file

for simplicity sake we use default domain configuration which uses profile "full" that defines two 

        server nodes as part of main-server-group

c) locate the profile "full" inside the domain.xml file and add new data sources

main data source used by jbpm

   <datasource jndi-name="java:jboss/datasources/psjbpmDS" 

                pool-name="postgresDS" enabled="true" use-java-context="true">

        <connection-url>jdbc:postgresql://localhost:5432/jbpm</connection-url>

        <driver>postgres</driver>

        <security>

            <user-name>jbpm</user-name>

                <password>jbpm</password>

        </security>

   </datasource>

        

        additional data source for quartz (non managed pool)

        <datasource jta="false" jndi-name="java:jboss/datasources/quartzNotManagedDS"   

           pool-name="quartzNotManagedDS" enabled="true" use-java-context="true">

      <connection-url>jdbc:postgresql://localhost:5432/jbpm</connection-url>

        <driver>postgres</driver>

        <security>

         <user-name>jbpm</user-name>

                <password>jbpm</password>

        </security>

    </datasource>

defined the driver used for the data sources

<driver name="postgres" module="org.postgresql">

      <xa-datasource-class>org.postgresql.xa.PGXADataSource</xa-datasource-class>

    </driver>

        

3. Configure security domain 

     a) go to JBOSS_HOME/domain/configuration

     b) edit domain.xml file

for simplicity sake we use default domain configuration which uses profile "full" that defines two

        server nodes as part of main-server-group

      

     c) locate the profile "full" inside the domain.xml file and add new security domain to define security 

         domain for jbpm-console (or kie-wb) - this is just a copy of the "other" security domain defined 

         there by default

    

<security-domain name="jbpm-console-ng" cache-type="default"> <authentication>

            <login-module code="Remoting" flag="optional">

               <module-option name="password-stacking" value="useFirstPass"/>

            </login-module>

            <login-module code="RealmDirect" flag="required">

                  <module-option name="password-stacking" value="useFirstPass"/>

            </login-module>

        </authentication>

    </security-domain>  

        

for kie-wb application, simply replace jbpm-console-ng with kie-ide as name of the security domain.  

        

4. Configure server nodes

    a) go to JBOSS_HOME/domain/configuration

    b) edit host.xml file

    c) locate servers that belongs to "main-server-group" in host.xml file and add following system  

        properties:

    

property name	property value	comments
org.uberfire.nio.git.dir	/home/jbpm/node[N]/repo	location where the VFS asset repository will be stored for the node[N]
org.quartz.properties	/jbpm/quartz-definition.properties	absolute file path to the quartz definition properties
jboss.node.name	nodeOne	unique node name within cluster (nodeOne, nodeTwo, etc)
org.uberfire.cluster.id	jbpm-cluster	name of the helix cluster
org.uberfire.cluster.zk	localhost:2181	location of the zookeeper server
org.uberfire.cluster.local.id	nodeOne_12345	unique id of the helix cluster node, note that ':' is replaced with '_'
org.uberfire.cluster.vfs.lock	vfs-repo	name of the resource defined on helix cluster
org.uberfire.nio.git.daemon.port	9418	port used by the GIT repo to accept client connections, must be unique for each cluster member
org.uberfire.nio.git.ssh.port	8001	port used by the GIT repo to accept client connections (over ssh), must be unique for each cluster member
org.uberfire.nio.git.daemon.host	localhost	host used by the GIT repo to accept client connections, in case cluster members run on different machines this property must be set to actual host name instead of localhost otherwise synchronization won't work
org.uberfire.nio.git.ssh.host	localhost	host used by the GIT repo to accept client connections (over ssh), in case cluster members run on different machines this property must be set to actual host name instead of localhost otherwise synchronization won't work
org.uberfire.metadata.index.dir	/home/jbpm/node[N]/index	location where index for search will be created (maintained by Apache Lucene)
org.uberfire.cluster.autostart	false	delays VFS clustering until the application is fully initialized to avoid conficts when all cluster members create local clones

    

examples for the two nodes:

    

•     nodeOne

<system-properties>

  <property name="org.uberfire.nio.git.dir" value="/tmp/jbpm/nodeone" 

                                       boot-time="false"/>

  <property name="org.quartz.properties" 

      value="/tmp/jbpm/quartz/quartz-db-postgres.properties" boot-time="false"/>

  <property name="jboss.node.name" value="nodeOne" boot-time="false"/>

  <property name="org.uberfire.cluster.id" value="jbpm-cluster" 

                                           boot-time="false"/>

    <property name="org.uberfire.cluster.zk" value="localhost:2181" 

                                           boot-time="false"/>

  <property name="org.uberfire.cluster.local.id" value="nodeOne_12345" 

                                                 boot-time="false"/>

  <property name="org.uberfire.cluster.vfs.lock" value="vfs-repo" 

                                                 boot-time="false"/>

  <property name="org.uberfire.nio.git.daemon.port" value="9418" boot-time="false"/>
  <property name="org.uberfire.metadata.index.dir" value="/tmp/jbpm/nodeone" boot-time="false"/>
  <property name="org.uberfire.cluster.autostart" value="false" boot-time="false"/>

</system-properties>

    

•     nodeTwo

<system-properties>

    <property name="org.uberfire.nio.git.dir" value="/tmp/jbpm/nodetwo" 

                                         boot-time="false"/>

    <property name="org.quartz.properties" 

       value="/tmp/jbpm/quartz/quartz-db-postgres.properties" boot-time="false"/>

    <property name="jboss.node.name" value="nodeTwo" boot-time="false"/>

    <property name="org.uberfire.cluster.id" value="jbpm-cluster" 

                                             boot-time="false"/>

    <property name="org.uberfire.cluster.zk" value="localhost:2181" 

                                             boot-time="false"/>

    <property name="org.uberfire.cluster.local.id" value="nodeTwo_12346" 

                                                   boot-time="false"/>

    <property name="org.uberfire.cluster.vfs.lock" value="vfs-repo" 

                                                   boot-time="false"/>

    <property name="org.uberfire.nio.git.daemon.port" value="9419" boot-time="false"/>
    <property name="org.uberfire.metadata.index.dir" value="/tmp/jbpm/nodetwo" boot-
     time="false"/>
    <property name="org.uberfire.cluster.autostart" value="false" boot-time="false"/>

</system-properties>

NOTE: since this example runs on single node host properties for ssh and git daemons are omitted.

Since repository synchronization is done between git servers make sure that GIT daemons are active (and properly configured - host name and port) on every cluster member.

5. Create user(s) and assign it to proper roles on application server

Add application users

In previous step security domain has been created so jbpm console (or kie-wb) users could be authenticated while logging on. Now it's time to add some users to be able to logon to the application once it's deployed. To do so:

 a) go to JBOSS_HOME/bin

 b) execute ./add-user.sh script and follow the instructions on the screen

  - use Application realm not management

  - when asked for roles, make sure you assign at least:

  for jbpm-console: jbpm-console-user

  for kie-wb: kie-user

 

add as many users you need, same goes for roles, listed above are required to be authorized to use the web application. 

Add management (of application server) user

To be able to manage the application server as domain, we need to add administrator user, it's similar to what was defined for adding application users but the realm needs to be management

 a) go to JBOSS_HOME/bin

 b) execute ./add-user.sh script and follow the instructions on the screen

  - use Management realm not application

Application server should be now ready to be used, so let's start the domain:

JBOSS_HOME/bin/domain.sh

after few seconds (it's still empty servers) you should be able to access both server nodes on following locations:

nodeOne: http://localhost:8080

nodeTwo: http://localhost:8230

administration console: http://localhost:9990/console

the port offset is configurable in host.xml for given server.

Deploy application - jBPM console (or kie-wb)

Now it's time to prepare and deploy application, either jbpm-console or kie-wb. As by default both application comes with predefined persistence that uses ExampleDS from AS7 and H2 data base there is a need to alter this configuration to use PostgreSQL data base instead.

Required changes in persistence.xml

• change jta-data-source name to match one defined on application server

             java:jboss/datasources/psjbpmDS

• change hibernate dialect to be postgresql 

             org.hibernate.dialect.PostgreSQLDialect

Application build from source

If the application is built from source then you need to edit persistence.xml file that is located under:

jbpm-console-ng/jbpm-console-ng-distribution-wars/src/main/jbossas7/WEB-INF/classes/META-INF/

next rebuild the jbpm-distribution-wars module to prepare deployable package - once that is named: 

jbpm-console-ng-jboss-as7.0.war

Deployable package downloaded

In case you have deployable package downloaded (which is already a war file) you need to extract it change the persistence.xml located under:

WEB-INF/classes/META-INF

once the file is edited and contains correct values to work properly with PostgreSQL data base application needs to be repackaged:

NOTE: before repackaging make use that previous war is not in the same directory otherwise it will be packaged into new war too.

jar -cfm jbpm-console-ng.war META-INF/MANIFEST.MF *

IMPORTANT: make sure that you include the same manifest file that was in original war file as it contains valuable entires.

To deploy application logon as management user into administration console of the domain and add new deployments using Runtime view of console. Once the deployment is added to the domain, assign it to the right server group - in this example we used main-server-group it will be default enable this deployment on all servers within that group - meaning deploy it on the servers. This will take a while and after successful deployment you should be able to access jbpm-console (or kie-wb) on following locations:

console on server one: http://localhost:8080/jbpm-console-ng

console on server one: http://localhost:8230/jbpm-console-ng

the context root (jbpm-console-ng) depends on the name of the war file that was deployed so if the filename will be jbpm-console-ng-jboss7.war then the context root will be jbpm-console-ng-jboss7. Same rule apply to kie-wb deployment.

And that's it - you should have fully operational jbpm cluster environment!!!

Obviously in normal scenarios you would like to hide the complexity of different urls to the application from end users (like putting in front of them a load balancer) but I explicitly left that out of this example to show proper behavior of independent cluster nodes.

Next post will go into details on how different components play smoothly in cluster, to name few:

• failover - in case cluster node goes down
• timer management - how does timer fire in cluster environment
• session management - auto reactivation of session on demand
• etc

As we are still in development mode, please share your thoughts on what would you like to see in cluster support for jBPM, your input is most appreciated!

Update:
There was a change in naming of system properties since the article was written so for those that configured it already for 6.0.0.Final there will be a need to adjust name of following system properties:

• org.kie.nio.git.dir -> org.uberfire.nio.git.dir
• org.kie.nio.git.daemon.port -> org.uberfire.nio.git.daemon.port
• org.kie.kieora.index.dir -> org.uberfire.metadata.index.dir
• org.uberfire.cluster.autostart - new parameter

Table above already contains proper values for 6.0.0.Final

jBPM web designer runs on VFS

As part of efforts for jBPM and Drools version 6.0 web designer is going through quite few enhancements too. One of the major features is to provide flexible mechanism to persist modeled processes (and other assets that relate to them such as forms, process image, etc) a.k.a assets even without being embedded in Drools Guvnor.
So let's start with the main part here - what does it mean flexible mechanism to persists assets? To answers this let's look at what is currently (jBPM 5.x) available:

• designer by default runs in embedded mode inside Drools Guvnor
• designer stores all assets inside Drools Guvnor JCR repository
• designer can run in standalone mode but only as modeling tool without capabilities to store assets

So as listed above there is only one option to persist assets - inside Drools Guvnor. In most of the cases this is good enough or even desired but there are quite few situation where modeling capabilities are required to be delivered with the custom application and including complete Drools Guvnor could be too much. 

That leads us to the flexible mechanism implemented - designer was equipped with Repository interface that is considered entry point to interact with underlying storage. Designer by default comes with Virtual File System based repository that provides:

• default implementation that supports 
• simple (local) file system repository
• git based repository
• allows for pluggable VFS provider implementations
• is based on standards - java NIO2

Extensions to what is delivered out of the box can be done in one of the following ways:

1. if VFS based repository is not what user needs an alternative implementation of the Repository interface can be provided, e.g data base
2. if VFS is what user is looking for but neither local file system nor git is the right implementation additional providers can be developed

Let's look little bit deeper into what these new features are and how users will benefit from them. 

1. It's based on Java 7 NIO2

VFS support provides is based on Java SE 7 NIO2 but does not require Java 7 to run as it comes with backport implementation of selected parts of NIO2 that are required

2. Different providers for Virtual File System

The simplest option is to use designer with local file system storage that will simply utilize file system on which designer is running. As most likely it will provide the best performance it leaves user with rather limited options when it comes to clustering, distributed environments or backups.

Next option that personally would recommend is to utilize GIT as underlying storage. People that works with GIT in their software development projects will most likely notice quite few advantages as in the end process definitions are more like source code that can be versioned, developed in parallel (branching) and included in some sort of release cycle.

3. Save process directly in designer editor

Designer now allows users to save process directly from the editor which will store the svg process content as well with just one click!

4. Repository menu

With the repository designer provides a simple UI menu to navigate through the repository and perform basic operations such as:

• open processes in designer editor
• create assets and directories
• copy/move assets
• delete assets and directories
• preview files

This menu is intended to be seen as basic file system browser utilized more in a standalone mode as when integrated with jBPM console-ng, guvnor-ng (UberFire) more advanced options will be delivered in this area.

5. Simpler integration with jBPM console and Drools Guvnor

Both jBPM console and Drools Guvnor are going to be "refreshed" for version 6.0 and thus integration between these components and designer will be simplified as they all will be unified on the repository level, meaning single repository can be shared across all these three components.

That will be all for a brief introduction but certainly not all in this topic. Expect more to come as soon as preview will be released on how to configure different repositories and more updates on git based repository on how to make best of it.

Your comments are more than welcome as they can help to make designer best modeling tool out there :)

Known limitation

Currently git based repository does not support move of assets and directories as atomic operation which means that preferred is to copy first and then delete.

Service Task with web service implementation

Invocation of web services as part of business process is common and most likely because of that default implementation of Service Task in BPMN2 specification is web service. Recently (5.4) jBPM5 has gotten support for such activity.

jBPM5 web service support is based on Apache CXF dynamic client. It provides dedicated Service Task handler (that implements WorkItemHandler interface).

org.jbpm.process.workitem.bpmn2.ServiceTaskHandler

Worth noting is that this handler is capable of invoking both web service end points and simple Java based services as with previous ServiceTask handler (org.jbpm.bpmn2.handler.SendTaskHandler) based on the implementation attribute of service task node

web service implementation

 <bpmn2:serviceTask id="ServiceTask_1" name="Service Task" implementation="##WebService" operationRef="_2_ServiceOperation"> </bpmn2:serviceTask>

java implementation

<bpmn2:serviceTask id="_2" name="Hello" operationRef="_2_ServiceOperation" implementation="Other" >

</bpmn2:serviceTask>

ServiceTaskHandler can invoke web service operations in three modes:

• synchronous (sends request and waits for response before continuing)
• asynchronous (sends request and uses callback to get response)
• one way (sends request and does not wait for any response)

This configuration is done on service node level as parameter (data input) so it allows to have different configuration for service nodes and to be handled by the same service task handler.

Let's try to go through this implementation with example. We are going to build a process that will get weather forecast for given zip codes in US. So process will look like this:

This process will:

• ask for couple of zip codes on the first human task (task is assigned to john)
• next transform result of the user task to a collection that will be used as input for multi instance service task
• then based on the input collection process will create several instances of service task to query the weather forecast service
• once all service task instances are completed it will log result to the console
• and create another human task to show the weather forecast for selected zip codes (task is assigned to john)

When process instance is started it will prompt the user to select in what mode service task instances should be executed: async or sync. With this particular example changing the mode from async to sync will not make big difference as the service we use is rather fast but with services that takes some time to respond difference will be noticeable.

But how does it know it is web service and even more important what web service it is? This is configured as part of process definition using few dedicated constructs:

1. first of all we need to tell the engine where is our WSDL so it can be read and operations from it can be invoked - this is done with BPMN2 import:
 <import importType="http://schemas.xmlsoap.org/wsdl/" location="http://wsf.cdyne.com/WeatherWS/Weather.asmx?WSDL" namespace="http://ws.cdyne.com/WeatherWS/"/>

2. next message, interface and operations must be defined:

<itemDefinition id="_2-2-4_InMessageType" />

<message id="_2-2-4_InMessage" itemRef="_2-2-4_InMessageType" />

<interface id="_2-2-4_ServiceInterface" name="" implementationRef="Weather">
 

  <operation id="_2-2-4_ServiceOperation"   

       implementationRef="GetCityWeatherByZIP" name="hello">
      <inMessageRef>_2-2-4_InMessage</inMessageRef>
  </operation>

</interface>

Important: make sure that implementationRef for both interface and operations point to valid service and operation in WSDL.

3. Next use defined operation in your service task and set implementation as web service (or don't specify that attribute at all so default will be taken):

<serviceTask id="_2" name="Service Task" operationRef="_2-2-4_ServiceOperation" implementation="##WebService" >

........

</serviceTask>

NOTE: Unfortunately tooling does not support this yet so the bpmn2 file needs to be edited by hand. Soon tooling will provide this as well.

Yet another important thing here is that if you plan to use request or response object of the service in your process as variables make sure that all of them implement java.io.Serializable interface so they can be properly persisted. One way to do this (used in the example) is to provide additional configuration to tell JAXB to add Serializable while generating classes from WSDL and generate classes as part of the build:

• create extra binding file
• configure cxf codegen maven plugin

Complete source code can be found here. It comes with test cases that uses this example as well as local service that can be used to illustrate difference between sync and async modes.

This example can be executed on jbpm-console when build from master, as it already has this service task handler configured. Here is a short guide on how to do it:
1. clone jbpm master and build it with mvn clean install -DskipTests -Dfull (alternatively download latest build from build server)
2. clone jbpm-examples and build jbpm-ws-example project with mvn clean install
3. copy result of build in point 2 (jbpm-ws-sample-1.0-SNAPSHOT.jar) into jbpm-installer/dependencies
4. copy WeatherWSServiceProcess.bpmn2 into jbpm-installer/sample/evaluation/src/main/resource
5. copy all archives from jbpm-distribution into jbpm-installer/lib
6. use jbpm-installer to install jbpm into jboss AS7 - ant install.demo.noeclipse
7. start demo server - ant start.demo.noeclipse

then go to jbpm-console and run the process with name WeatherWSServiceProcess.

Have fun!

JUDCon2012 - Boston

JUDCon 2012 in Boston was a great place to meet with fellow developers and discuss about future of jBPM. I had a pleasure to give a talk about experimental project that I have been working on for quite some time, but unfortunately not enough time was spent on it. Anyway, I gave a introduction to the project that I use to call jbpm enterprise.

The goal of this project is to provide comprehensive BPM platform on top of jBPM and Drools projects to leverage the most of them in the enterprise (Java EE) environment. So what it does?

• First of all it bundles jbpm and drools (together with all dependencies) into JBoss Module. 
• Next it provides very tiny layer that abstracts knowledge api and provides simplified interfaces to interact with execution engine (execution engine is knowledge base with sessions enclosed by an component with additional characteristics - more in presentation)
• exposes some services via OSGi service repository
• provides maven archetypes to build your components that utilize the platform over OSGi service registry
• bundle archetype that is dedicated to put you process/rules/events logic in
• web application archetype that makes use of the platform (starts, signal processes, etc)

More details can be found in the presentation from the JUDCon2012 conference.

jBPM&Drools go Enterprise - JUDCon2012

If some one would like to give it a test drive please find a downloadable artefacts and short guide here.

Have fun and as usual comments are welcome.

In this case your feedback is even more important to see if that is something that community expects.

jBPM 5.3 brings LDAP into the picture

jBPM engine itself does not require to have knowledge about users and groups but to build more complete platform based on it sooner or later users and their memberships will be needed. Prior to version 5.3, jBPM relied on basic (and demo only) setup based on some property files. With 5.3 you can make use of integration that allow to employ existing LDAP server.

So, let's start digging into it :)

User and group information are relevant to two components:

• jbpm console
• human task server

jbpm console need to know about users and their roles to properly authenticate and grant them with correct access in the console.
Human task server has bit more to do with users and groups. First of all it requires it when assigning task to entities (either user or group). Next, in case notification mechanism is configured it requires to fetch more information about the entity (such as email address, etc.)

Bit of heads up is always welcome, but how this can be configured and used? Firstly, we need to have a LDAP server that could be used as user repository. If you have already one this step can be omitted.

Install and configure LDAP server

Install and configure LDAP server of your choice, I personally use OpenLDAP that can be downloaded and used freely for evaluation purpose. Regardless of your choice most likely the best guide on installation and configuration is to be found on the server home page.

Note: make sure that when configuring your LDAP server inetOrgPerson schema is included otherwise import of example ldif will fail.

Once the server is up and running it's time to load it with some information that will be used later on by jBPM. Following is a sample setup of users and groups that matches the one used in previous versions of jBPM5 (Example ldif file expect that there is already domain configured (dc=jbpm,dc=org)):

Sample LDIF file

Rest of the post assumes that LDAP server is installed on the same machine as application server that hosts jbpm (but it is not limited to that).

Configure JBoss AS7 security domain to use LDAP

Next step is to configure application server that host jbpm console to authenticate users using LDAP instead of the default property file based security domain. In fact there are no changes needed to jbpm console itself but only to JBoss AS7 configuration.
To use LDAP, jbpm-console security domain inside standalone.xml file should be replaced with:
 <security-domain name="jbpm-console">
      <authentication>
         <login-module code="org.jboss.security.auth.spi.LdapExtLoginModule" flag="required">
             <module-option name="baseCtxDN" value="ou=People,dc=jbpm,dc=org"/>
             <module-option name="baseFilter" value="(uid={0})"/>
             <module-option name="rolesCtxDN" value="ou=Roles,dc=jbpm,dc=org"/>
             <module-option name="roleFilter" value="(member=uid={0},ou=People,dc=jbpm,dc=org)"/>
             <module-option name="roleAttributeID" value="cn"/>
             <module-option name="allowEmptyPasswords" value="true"/>
         </login-module>
     </authentication>
 </security-domain>
This is pure JBoss configuration so in case of more advanced setup is required please visit JBoss AS7 documentation.

Note that from jBPM 5.3 jbpm console is capable of using any security domain that JBoss AS supports with just configuring it properly on application server so it is not limited to LDAP.

Configure Human task server to use LDAP

Finally it is time to look into the details of human task server configuration to make it use of LDAP as user repository. Those that are following jBPM development are already familiar with UserGroupCallback interface that is responsible for providing user and group/role information to the task server. So naturally LDAP integration is done through implementation of that interface.
Similar to configuring application server, ldap callback needs to be configured (with property file for instance). Here is a sample file that corresponds to the configuration used throughout the post:

ldap.user.ctx=ou\=People,dc\=jbpm,dc\=org
ldap.role.ctx=ou\=Roles,dc\=jbpm,dc\=org
ldap.user.roles.ctx=ou\=Roles,dc\=jbpm,dc\=org
ldap.user.filter=(uid\={0})
ldap.role.filter=(cn\={0})
ldap.user.roles.filter=(member\={0})

As from 5.3 by default human task server is deployed as web application on Jboss AS7. With this, user can simply adjust configuration of the human task server by editing its web.xml file. And this is how LDAP callback is registered.

<init-param>
     <param-name>user.group.callback.class</param-name>
     <param-value>org.jbpm.task.service.LDAPUserGroupCallbackImpl</param-value>

</init-param>

Next put the jbpm.usergroup.callback.properties on the root of the classpath inside jbpm-human-task.war web application and your LDAP callback will be ready to rock!

In addition, when using deadlines on your tasks together with notification, there is one more step to configure so user information (for instance email address) could be retrieved from LDAP server. UserInfo interface is dedicated to providing this sort of information to the deadline handler and thus it's implementation needs to registered as well.
Similar as user group callback was registered it can be done via web.xml of human task web application:

<init-param>
     <param-name>user.info.class</param-name>
     <param-value>org.jbpm.task.service.LDAPUserInfoImpl</param-value>

</init-param>

It requires to be configured as well and it could be done via property file that should be named jbpm.user.info.properties and be placed on root of the class path.
As it shares most of the properties with callback configuration, in many cases users could use single file that contains all required values and instruct both implementation where to find this file with system properties:

-Djbpm.user.info.properties=classpath-location-and-file-name

-Djbpm.usergroup.callback.properties=classpath-location-and-file-name

With all that jBPM will now utilize your LDAP server for users and groups information whenever it needs them.

P.S.
This post is more of introduction to the LDAP integration rather than complete and comprehensive guide as it touches on high level all the components involved. More detailed information about configuring particular pieces can be found in jBPM documentation for 5.3 release.

Any comments are more than welcome.