A Bpel Overview

IBM United Kingdom Ltd

Workflow - A Business View

John Ibbotson Francisco Curbera

IBM UK Ltd IBM Research

10/14/08

© 2003 IBM Corporation

IBM United Kingdom Ltd

Motivation 

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Application integration is a key problem facing businesses –

Intra enterprise integration (Enterprise Application Integration)

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Integrating with partners (Business Process Integration)

Web services are enabling the move towards serviceoriented computing –

Applications are viewed as “services”

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Loosely coupled, dynamic interactions

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Heterogeneous platforms

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No single party has complete control

Application integration => Service composition –

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How do you compose services in this domain?

10/14/08

© 2003 IBM Corporation

IBM United Kingdom Ltd

BPEL4WS for Application Integration .net WAS

PROVENANCE Process brokering

SOAP, Transactions Business Process

Service Description RMI IIOP

Service Description MQSeries

Delivery channels

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Legacy integration

CICS

MQSeries

10/14/08

© 2003 IBM Corporation

IBM United Kingdom Ltd

Process Model Requirements  

Portability and Interoperability Flexible Integration –

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Rich, and easily adaptable to changes in the services it is interacting with

Recursive, type-based composition –

Enables: • • • •

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Separation and composability of concerns –

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Can carry multiple stateful long-running conversations

Recoverability –

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Decoupled from the supporting mechanisms (quality of service, messaging frameworks)

Stateful conversations and lifecycle management –

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third-party composition of existing services, providing different views on a composition to different parties, inter-workflow interaction, and increased scalability and reuse

Business processes, and in particular long running ones, need a way to build-in fault handling and compensation mechanisms to handle and recover from errors.

10/14/08

© 2003 IBM Corporation

IBM United Kingdom Ltd

Two-level Programming Model  Programming in the small – base services – Programmers implementing functions – Function logic deals with a discrete fine-grained task (such as retrieving an order document or updating a customer record)

 Programming in the large – BPEL and SCA – Non-programmers implementing flows – Flow logic deals with combining many functions in order to solve a more complex problem (such as processing an order)

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© 2003 IBM Corporation

IBM United Kingdom Ltd

BPEL Processes and interactions are Strongly Typed  BPEL is built on WSDL described services – Strongly typed

 A BPEL process interacts with the

world through a set of strongly typed channels: – Partner link = pair of WSDL port types – BPEL flows are tightly coupled to specific interfaces and message types

Process WSDL Service B

 BPEL supports traditional WfMS

properties: – Statically analyzable – Transactional, reliable, monitored execution, etc. – Fits well the (SOA) model of application to application integration through well defined service interfaces

B’s WSDL

 But BPEL is being extended to support interaction with human actors – BPEL4People: services implemented by people

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Partner Link

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© 2003 IBM Corporation

IBM United Kingdom Ltd

BPEL Composition of Web Services Process WSDL Service B

B’s WSDL

Partner Link

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© 2003 IBM Corporation

IBM United Kingdom Ltd

BPEL in Scientific Flows - questions  Scientific flows are likely to be: – Heterogeneous in control and data, – Dynamic

 But also require – Monitoring, auditing, compliance with specific policies

 Both types of workflows are likely to be part of any realistic scientific workflow.

– How do we integrate these different models? • Business and Scientific

– Can we provide flexibility and robustness, dynamic change and monitoring at the same time

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10/14/08

© 2003 IBM Corporation