Web Services
Business Process Execution Language Version 2.0
Working Draft 01, 018
September December 2004
Document identifier:
wsbpel-specification-draft-01
Location:
http://www.oasis-open.org/apps/org/workgroup/wsbpel/
Editors:
Assaf Arkin
<arkin@intalio.com>
Sid Askary <saskary@nuperus.com>
Ben Bloch <ben_b54@hotmail.com>
Francisco Curbera,
IBM <curbera@us.ibm.com>
Yaron Goland, BEA <ygoland@bea.com>
Neelakantan Kartha,
Sterling Commerce <N_Kartha@stercomm.com>
Canyang Kevin Liu,
SAP <kevin.liu@sap.com>
Satish Thatte,
Microsoft <satisht@microsoft.com>
Prasad Yendluri,
webMethods <pyendluri@webmethods.com>
Alex Yiu, Oracle <alex.yiu@oracle.com>
Contributors:
{FirstName} {Last
Name}, {Organization}
Editor’s
Notes – KevinL – this section should be consolidated with Appendix H
This
document defines a notation for specifying business process behavior based on
Web Services. This notation is called Web Services Business
Process Execution Language for Web Services (abbreviated to BPEL4WS
WS-BPEL in the rest of this document).
Processes in BPEL4WSWS-BPEL
export and import functionality by using Web Service interfaces exclusively.
Business
processes can be described in two ways. Executable business processes model
actual behavior of a participant in a business interaction. Business protocols,
in contrast, use process descriptions that specify the mutually visible message
exchange behavior of each of the parties involved in the protocol, without
revealing their internal behavior. The process descriptions for business
protocols are called abstract processes. BPEL4WSWS-BPEL
is meant to be used to model the behavior of both executable and abstract
processes.
BPEL4WSWS-BPEL
provides a language for the formal specification of business processes and
business interaction protocols. By doing so, it extends the Web Services
interaction model and enables it to support business transactions. BPEL4WSWS-BPEL
defines an interoperable integration model that should facilitate the expansion
of automated process integration in both the intra-corporate and the
business-to-business spaces.
This is
a draft version of the WS-BPEL TC specification, updated from the origninal
BPEL4WS V1.1 specification dated May 5, 2003 that was submitted to the WS BPEL
TC. See: http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/2046/BPEL%20V1-1%20May%205%202003%20Final.pdf
If you
are on the <wsbpel@lists.oasis-open.org> list for committee members, send comments
there. If you are not on that list, subscribe to the <wsbpel-comment@lists.oasis-open.org> list and send comments there. To
subscribe, send an email message to <mailto:wsbpel-comment-request@lists.oasis-open.org> with the word "subscribe"as
the body of the message.
For
information on whether any patents have been disclosed that may be essential to
implementing this specification, and any offers of patent licensing terms,
please refer to the Intellectual Property Rights section of the WS-BPEL TC web
page http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=wsbpel
Copyright © 2004
OASIS Open, Inc. All Rights Reserved.
Table of Contents
1. Introduction
3. Relationship with Other Specifications
4. What Changed from BPEL4WS 1.0This Section Has Been Deleted
4.1. Core Concepts Clarification
4.2. Terminology Changes
4.3. Feature Changes
5. Core Concepts and Usage Patterns
6. Defining a Business Process
6.1. Initial Example
6.2. The Structure of a Business Process
6.4. The Lifecycle of a Business Process
7. Partner Link Types, Partner Links, and Endpoint
References
7.1. Partner Link Types
7.2. Partner Links
7.3. Business Partners
7.4. Endpoint References
8.1. Motivation
8.2. Defining Properties
9.1. Expressions
9.2. Variables
9.3. Assignment
10. Correlation
10.1. Message
Correlation
10.2. Defining and Using Correlation
Sets
11. Basic Activities
11.1. Standard Attributes for Each Activity
11.2. Standard Elements for Each Activity
11.3. Invoking Web Service Operations
11.4. Providing Web Service Operations
11.5. Updating Variable Contents
11.6. Signaling Faults
11.7. Waiting
11.8. Doing Nothing
12.1. Sequence
12.2. Switch
12.3. While
12.4. Pick
12.5. Flow
13. Scopes
13.1. Data Handling and Partner Links
13.2. Error Handling in Business Processes
13.3. Compensation Handlers
13.4. Fault Handlers
13.5. Event Handlers
13.6. Serializable Scopes
14. Extensions for Executable Processes
14.1. Expressions
14.2. Variables
14.3. Assignment
14.4. Correlation
14.5. Web Service Operations
14.6. Terminating a Service Instance
14.7. Compensation
14.8. Event Handlers
15. Extensions for Business Protocols
15.1. Variables
15.2. Assignment
16. Examples
16.1. Shipping Service
16.2. Loan Approval
16.3. Multiple Start Activities
Appendixes
C. XSD Schemas
D. Notices
E. Intellectual Property Rights
G. References
H. Committee Members (Non-Normative)
1. Introduction
The goal of the Web Services
effort is to achieve universal interoperability between applications by using
Web standards. Web Services use a loosely coupled integration model to allow
flexible integration of heterogeneous systems in a variety of domains including
business-to-consumer, business-to-business and enterprise application
integration. The following basic specifications originally defined the Web
Services space: SOAP, Web Services Description Language (WSDL), and Universal
Description, Discovery, and Integration (UDDI). SOAP defines an XML messaging
protocol for basic service interoperability. WSDL introduces a common grammar
for describing services. UDDI provides the infrastructure required to publish
and discover services in a systematic way. Together, these specifications allow
applications to find each other and interact following a loosely coupled,
platformindependent model.
Systems integration requires more than the ability to conduct simple interactions by using standard protocols. The full potential of Web Services as an integration platform will be achieved only when applications and business processes are able to integrate their complex interactions by using a standard process integration model. The interaction model that is directly supported by WSDL is essentially a stateless model of synchronous or uncorrelated asynchronous interactions. Models for business interactions typically assume sequences of peer-to-peer message exchanges, both synchronous and asynchronous, within stateful, long-running interactions involving two or more parties. To define such business interactions, a formal description of the message exchange protocols used by business processes in their interactions is needed. The definition of such business protocols involves precisely specifying the mutually visible message exchange behavior of each of the parties involved in the protocol, without revealing their internal implementatio