IBM WebSphere survey

Kristian Bisgaard Lassen

University of Aarhus IBM WebSphere survey 2

Tools

WebSphere Application Server Portal Studio Business Integration Server

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BPEL4WS (abbr. BPEL)

Business Process Execution Language for Web Services (OASIS specification)

XML syntax and typed by XML Schema

Mapped to EJB components

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Example of BPEL

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Modeling features

Sequencing (dashed arrow) Concurrency (free grouping) Synchronization (solid arrow) Hierarchy (sub process) Reuse (instances)

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WSDL description

Web Service Definition Language Port type

Describes the operations the process supports

Operation Defined by input and output messages

Both does not need to be defined Similar to a function declaration

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BPEL general

Describes processes by what activities they perform and which processes they interact with

Visualization of a BPEL process can be done in several ways in contrast to e.g. state charts

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Basic activity content (1)

Name Join condition

Default expression is a logic OR of link status of incoming links

Can be defined as any Boolean expression

Suppress join failure (yes | no)

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Basic activity content (2)

Source links Optional transition condition

Target links

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Basic activity content (3)

All activities can have event handlers

Event handlers are invoked concurrently with the activity

Semantics of event handlers are similar to that of the Pick activity

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BPEL process activities (1)

Receive Blocking wait for a message

Reply Constructs a message to a message

received in a Receive activity

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BPEL process activities (2)

Invoke Allows a process to invoke a one-way

operation on a port type offered by a partner

Possible to specify Exception handlers Compensation handlers

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BPEL process activities (3)

Assign Update variables with data

Throw Generate a named exception

Wait Makes the process wait for a certain

period of time

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BPEL process activities (4)

Empty No operation Useful for

Synchronization Suppressing exceptions

Sequence Perform activities sequentially

Switch Allows conditional branching

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BPEL process activities (5)

While Perform a certain activity until a

condition is meet Pick

Blocking activity waiting for a message or an ‘alarm’ to go off

Flow Construct allows one or more activity to

be performed concurrently

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BPEL process activities (6)

Scope A nested activity

Compensate Fault handler for scoped activities

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Process lifecycle

BPEL4WS processes are long running stateful interactions

Process instantiation is implicit Termination can happen if

The activity completes normally A fault is reached in the process scope Explicit termination

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Partner links (1)

The type characterizes relationship between two services by roles (e.g. buyer and seller) A role specifies a WSDL port type

Partner link is an instantiation of a partner link type

Partners can be selected both statically and dynamically through assignment (Assign)

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Partner links (2)

Business partner A subset of a partner link type

Endpoint reference Dynamical reference of port. Used

typically when a certain instance of a service is needed

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Business Process Choreographer

BPEL processes can be contained in BPC

BPC add to BPEL staff activities Activities which requires human

interaction

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Staff activity

When a staff activity is invoked work items are generated

A role can have three roles Potential owner

Can claim the activity, complete it or transfer it to another potential owner

Editor Can add information to the work item but not

complete it Reader

Can only check the work item status

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BPEL+

WebSphere specific Integrated with Java, e.g. in

Variable type declarations Transition conditionals In Invoke constructs

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WebSphere Studio (1)

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WebSphere Studio (2)

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WebSphere Studio (3)

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Future work

Develop a running example of something in WebSphere Studio

Port the Bankdata model to BPEL or BPEL+ in WebSphere Studio

Compare BPEL to the Eindhoven business flow model

Investigate ways to restrict CPN models so they can translate to BPEL