Business Process Execution Language (BPEL)
BPEL is an orchestration language to compose multiple Web Services together into
another Web Service. BPEL adopts Web Services as its external communication mechanism.
Thus BPEL's messaging facilities depend on the use of the
Web Services Description Language (WSDL)
1.1 to describe outgoing and incoming messages.
In addition to providing facilities to enable sending and receiving messages,
the BPEL programming language also supports:
- A property-based message correlation mechanism
- XML and WSDL typed variables
- An extensible language plug-in model to allow writing expressions and
queries in multiple languages: BPEL supports Xpath 1.0 by default
- Structured-Programming constructs including if-then-elseif-else, while,
sequence (to enable executing commands in order) and flow (to enable
executing commands in parallel)
- A scoping system to allow the encapsulation logic with local variables,
fault handlers, compensation handlers and event handlers
- Serialized scopes to control concurrent access to variables
BPEL 2.0 Specification (PDF)
- OASIS Standard Edition, dated 11 April, 2007
site contains many useful links and references.