Events

Start Event:

- Start Event is a starting node which indicates the starting point of an instance of a process.

- It is permissible for a process to have no Start Events but instead it must have one or more Start Message Events.  These allow the process to be started from an external event such as a UCA.

End Event:

- End Event is used to model the end of a process. There can be multiple End Event nodes in a diagram.

- The process instance will come to an end only when all the concurrently executing branches reach their End Events.

Message Start Event:

- Message Start Event can be used to initiate an instance of a process due to the arrival of an event.

- An instance of the process can be started based on this element when an external event occurs.

Message Intermediate Event:

- Message Intermediate Event is an Event listener that is used to listen for incoming events within a process instance that is already running.

Message End Event:

- Message End Event ends the current path of the process and fires an event.

Timer Event:

- Timer Event can be added as an attribute on an existing task or can be an element in its own right.

Tracking Intermediate Event:

- Tracking Intermediate Event is used to generate a data point used in performance reporting on process instances.

Ad-hoc Start Event:

- Ad-hoc Start Event is a mechanism that allows us to start a chain of activities in an already existing process instance.

Terminate Event:

- Terminate Event will cause the immediate termination of a process instance.

Error Intermediate Event:

- Control is passed to this event handler when an exception is caught within the implementation of that activity.

Error Event:

- Error Event, if a process detects that an error condition has occurred, it can terminate the remaining and current steps of the process and throw an Exception.

Business Process Definition - BPD

BPD   
- The Business Process Definition is the core of the IBM BPM solutions. BPD is a diagram that represents the overall view and flow of the business process.

Fig: BPD with all components 

Pools and lanes

- The canvas as a whole represents the pool while multiple lanes can be added to segment the pool into horizontal sections.

Fig: Pools and Lanes

Sequence lines

- Sequence lines are drawn to connect the individual steps in the BPD. A sequence line describes which activities will follow other activities in sequence as the process executes. 

Activities

Fig: Initial Properties of Activity

- Activities are the core element in the process. These are the declarations that some work is going to be performed.

- Data mapping is the mapping of the variables in scope in the BPD to the expected parameters of the service that is to be called by the Activity.

- When an Activity is reached in the BPD, it may not always be applicable to execute this activity but instead it can be skipped over by using an condition attribute.

BPD Diagram Notes 

- Notes are documentation items added to the BPD diagram. They appear as yellow rectangles into which text can be entered.

Architecture Of IBM BPM

- The heart of the IBM BPM is Process Center and Process Center Server.

- We can communicate with the Process Center through process designer, process center console and process admin console.

- Process Center uses the BPM repository to store all business process definitions. Repository uses the SQL database and it automatically provides the version for all stored assets.

- Process designer is eclipse based application,allows to create or edit the business process and manages the server environment.

- Process center console is browser based application, it manages the server, assets and relationships. It does not allow us to create or edit the business process.

- Process admin console is browser based application, it manages the run time features such as coaches,variable,events and users as well.

- Performance database warehouse is an optional database but necessary for monitoring.

- Process center server is run time component where business process run. When working with the process designer, the current version of the business process will run in the tip of the process center server. As development progresses, the business process applications need to deploy in different environments such as test environment, quality assurance environment and production environment. Each environment has its own set of database.

- Its important to note that BPM Express does not provide the server clustering.