BPEL

Business Process Engineering Language

A technology used to build programs in SOA architecture

Business processes

Business Process

• ProcessProcess is a sequence of steps that is:– initiated by an event,

– transforms its inputs (in many repsects) and

– produces a specified output.

• A business process business process is a set of logically related tasks performed to achieve a well-defined business outcome. – Defines the results to be achieved, the context of the

activities, the relationships between the activities & the interactions with other processes and resources

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Web Services & Business Processes

• Building composite services by combining existing elementary or complex services– requires coordinating the flow of control and

information between the component services. • Business logic can be seen as the ingredient

that sequences, coordinates, and manages interactions among web services.

• Techniques for Web services composability draw heavily on business process modelling and workflow processing languages.

Flow Model

• How to combine?

• Order execution

• Decision points

• Passing data

Transition conditions

Service Composition

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WS orchestration vs. choreography

• Orchestration describes how WSs can interact at the message level, from the perspective and under control of a single endpoint (single party).

• Choreography – is associated with the public message exchanges, rules of

interaction & agreements that occur between multiple business process endpoints.

– tracks the sequence of messages that may involve multiple parties & multiple sources, & described from the perspectives of all parties (common view).

BPEL an orchestration language

• models business process collaboration (<partnerLink>s),

• models the execution control of business processes,

• separates abstract definition from concrete binding,

• supports fault handling & compensation,

• supports service composability (structured activities can be nested and combined arbitrarily),

• supports context (<scope> mechanism),

• spawns off & synchronizes processes (<pick> & <receive> activities),

• supports event-handling.

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