Book Image

Business Process Execution Language for Web Services 2nd Edition

Book Image

Business Process Execution Language for Web Services 2nd Edition

Overview of this book

Web services provide the basic technical platform required for application interoperability. They do not, however, provide higher level control, such as which web services need to be invoked, which operations should be called and in what sequence. Nor do they provide ways to describe the semantics of interfaces, the workflows, or e-business processes. BPEL is the missing link to assemble and integrate web services into a real business process BPEL4WS standardizes process automation between web services. This applies both within the enterprise, where BPEL4WS is used to integrate previously isolated systems, and between enterprises, where BPEL4WS enables easier and more effective integration with business partners. In providing a standard descriptive structure BPEL4WS enables enterprises to define their business processes during the design phase. Wider business benefits can flow from this through business process optimization, reengineering, and the selection of most appropriate processes . Supported by major vendorsó including BEA, Hewlett-Packard, IBM, Microsoft, Novell, Oracle, SAP, Sun, and othersó BPEL4WS is becoming the accepted standard for business process management. This book provides detailed coverage of BPEL4WS, its syntax, and where, and how, it is used. It begins with an overview of web services, showing both the foundation of, and need for, BPEL. The web services orchestration stack is explained, including standards such as WS-Security, WS-Coordination, WS-Transaction, WS-Addressing, and others. The BPEL language itself is explained in detail, with Code snippets and complete examples illustrating both its syntax and typical construction. Having covered BPEL itself, the book then goes on to show BPEL is used in context. by providing an overview of major BPEL4WS servers. It covers the Oracle BPEL Process Manager and Microsoft BizTalk Server 2004 in detail, and shows how to write BPEL4WS solutions using these servers.
Table of Contents (14 chapters)
Business Process Execution Language for Web Services
Credits
About the Authors
About the Reviewers
Preface
Index

Deadline and Duration Expressions


To specify deadlines and durations for activities, BPEL uses lexical representations of corresponding XML Schema data types. For setting deadlines, the data types are either dateTime or date. For setting the duration (a timeout, for instance), you can use the duration data type. The lexical representation of expressions should conform to the XPath 1.0 (or the selected query language) specifications. Such expressions should evaluate to values of corresponding XML Schema types: dateTime and date for deadline and duration for duration expressions.

All three data types use lexical representations that conform to the ISO 8601 standard. For more information on this standard, see the ISO web page at http://www.iso.ch. The ISO 8601 lexical format uses characters within date and time information. Characters are appended to the numbers and have the following meaning:

  • C represents centuries.

  • Y represents years.

  • M represents months.

  • D represents days.

  • h represents hours.

  • m represents minutes.

  • s represents seconds. Seconds can be represented in the format ss.sss to increase precision.

  • Z is used to designate Coordinated Universal Time (UTC). It should immediately follow the time-of-day element.

For the dateTime expressions, there is an additional designator:

  • T is used as a time designator that indicates the start of the representation of the time.

For duration expressions, the following characters can also be used:

  • P is used as the time duration designator. Duration expressions always start with P.

  • Y represents the number of years.

  • M represents the number of months or minutes.

  • D represents the number of days.

  • H represents the number of hours.

  • S represents the number of seconds.