XPDL
Encyclopedia
The XML
Process Definition Language (XPDL) is a format standardized by the Workflow Management Coalition
(WfMC) to interchange business process
definitions between different workflow
products, i.e. between different modeling tools and management suites.
XPDL defines an XML schema for specifying the declarative part of workflow / business process.
XPDL is designed to exchange the process definition, both the graphics and the semantics of a workflow business process. XPDL is currently the best file format for exchange of BPMN
diagrams; it has been designed specifically to store all aspects of a BPMN diagram. XPDL contains elements to hold graphical information, such as the X and Y position of the nodes, as well as executable aspects which would be used to run a process. This distinguishes XPDL from BPEL
which focuses exclusively on the executable aspects of the process. BPEL does not contain elements to represent the graphical aspects of a process diagram.
It is possible to say that XPDL is the XML
Serialization
of BPMN.
, founded in August 1993, began by defining the Workflow Reference Model
(ultimately published in 1995) that outlined the five key interfaces that a workflow management system must have. Interface 1 was for defining the business process, which includes two aspects: a process definition expression language and a programmatic interface to transfer the process definition to/from the workflow management system.
The first revision of a process definition expression language was called Workflow Process Definition Language (WPDL) which was published in 1998. This process meta-model contained all the key concepts required to support workflow automation expressed using URL Encoding. Interoperability demonstrations were held to confirm the usefulness of this language as a way to communicate process models.
By 1998, the first standards based on XML began to appear. The utility of using an XML syntax upon which to base an interchange language was apparent. The Workflow Management Coalition Working Group 1 produced an updated process definition expression language called XML Process Definition Language (XPDL) now known as XPDL 1.0. This second revision was an XML based interchange language that contained many of the same concepts as WPDL, with some improvements. XPDL 1.0 was ratified by the WfMC in 2002, and was subsequently implemented by more than two dozen workflow/BPM products to exchange process definitions. There was a large number of research projects and academic studies on workflow capabilities around XPDL, which was essentially the only standard language at the time for interchange of process design.
The WfMC continued to update and improve the process definition interchange language. In 2004 the WfMC endorsed BPMN, a graphical formalism to standardize the way that process definitions were visualized. XPDL was extended specifically with the goal to be able to represent in XML all of the concepts present in a BPMN diagram. This third revision of a process definition expression language is known as XPDL 2.0 and was ratified by the WfMC in Oct of 2005.
In April 2008, the WfMC ratified XPDL 2.1 as the fourth revision of this specification. XPDL 2.1 includes extension to handle new BPMN 1.1 constructs, as well as clarification of conformance criteria for implementations.
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
Process Definition Language (XPDL) is a format standardized by the Workflow Management Coalition
Workflow Management Coalition
Workflow Management Coalition is a consortium, formed to define standards for the interoperability of workflow management systems. It was founded in May 1993 as an offshoot of the Black Forest Group with original members including IBM, Hewlett-Packard, Fujitsu, ICL, Staffware and approximately 300...
(WfMC) to interchange business process
Business process
A business process or business method is a collection of related, structured activities or tasks that produce a specific service or product for a particular customer or customers...
definitions between different workflow
Workflow
A workflow consists of a sequence of connected steps. It is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work...
products, i.e. between different modeling tools and management suites.
XPDL defines an XML schema for specifying the declarative part of workflow / business process.
XPDL is designed to exchange the process definition, both the graphics and the semantics of a workflow business process. XPDL is currently the best file format for exchange of BPMN
Business Process Modeling Notation
Business Process Model and Notation is a graphical representation for specifying business processes in a business process model. It was previously known as Business Process Modeling Notation....
diagrams; it has been designed specifically to store all aspects of a BPMN diagram. XPDL contains elements to hold graphical information, such as the X and Y position of the nodes, as well as executable aspects which would be used to run a process. This distinguishes XPDL from BPEL
Business Process Execution Language
Business Process Execution Language , short for Web Services Business Process Execution Language is an OASIS standard executable language for specifying actions within business processes with web services...
which focuses exclusively on the executable aspects of the process. BPEL does not contain elements to represent the graphical aspects of a process diagram.
It is possible to say that XPDL is the XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
Serialization
Serialization
In computer science, in the context of data storage and transmission, serialization is the process of converting a data structure or object state into a format that can be stored and "resurrected" later in the same or another computer environment...
of BPMN.
History
The Workflow Management CoalitionWorkflow Management Coalition
Workflow Management Coalition is a consortium, formed to define standards for the interoperability of workflow management systems. It was founded in May 1993 as an offshoot of the Black Forest Group with original members including IBM, Hewlett-Packard, Fujitsu, ICL, Staffware and approximately 300...
, founded in August 1993, began by defining the Workflow Reference Model
Workflow Reference Model
First published in 1995 the Workflow Reference Model was developed by the Workflow Management Coalition to define a workflow management system and to identify the most important system interfaces. Other WfMC standards make reference to this model.*...
(ultimately published in 1995) that outlined the five key interfaces that a workflow management system must have. Interface 1 was for defining the business process, which includes two aspects: a process definition expression language and a programmatic interface to transfer the process definition to/from the workflow management system.
The first revision of a process definition expression language was called Workflow Process Definition Language (WPDL) which was published in 1998. This process meta-model contained all the key concepts required to support workflow automation expressed using URL Encoding. Interoperability demonstrations were held to confirm the usefulness of this language as a way to communicate process models.
By 1998, the first standards based on XML began to appear. The utility of using an XML syntax upon which to base an interchange language was apparent. The Workflow Management Coalition Working Group 1 produced an updated process definition expression language called XML Process Definition Language (XPDL) now known as XPDL 1.0. This second revision was an XML based interchange language that contained many of the same concepts as WPDL, with some improvements. XPDL 1.0 was ratified by the WfMC in 2002, and was subsequently implemented by more than two dozen workflow/BPM products to exchange process definitions. There was a large number of research projects and academic studies on workflow capabilities around XPDL, which was essentially the only standard language at the time for interchange of process design.
The WfMC continued to update and improve the process definition interchange language. In 2004 the WfMC endorsed BPMN, a graphical formalism to standardize the way that process definitions were visualized. XPDL was extended specifically with the goal to be able to represent in XML all of the concepts present in a BPMN diagram. This third revision of a process definition expression language is known as XPDL 2.0 and was ratified by the WfMC in Oct of 2005.
In April 2008, the WfMC ratified XPDL 2.1 as the fourth revision of this specification. XPDL 2.1 includes extension to handle new BPMN 1.1 constructs, as well as clarification of conformance criteria for implementations.
External links
- XPDL 2.1
- XPDL & Workflow Patterns PDF
- Critical comments on XPDL 1.0
- Enterprise Workflow National Project supported by the Office of the Deputy Prime Minister endorses WfMC standards for use in all workflow projects in UK.