Transaction and Rule Support for Workflow Management - A Retrospective on the WIDE Architecture Paul Grefen CS Department & CTIT University of Twente

Workflow on Intelligent Distributed database Environment

W I D E A p p r o a c h

Extended transaction support –Loose global transactions (saga) –Strict local transactions (nested) Active rule support –Decoupled execution mode –Workflow, data, external, time events Data support –Object-oriented client interface –Relational server interface –IDL-SQL/C++ compiler support D B M S E x t e n s i o n s

Advanced data support versus workflow support –reusability of advanced data support Extended transaction support versus active rule support –orthogonal and flexible semantics –adaptability of transaction/rule support WIDE integrated workflow system vs. commercial DBMS –portability of WIDE WFMS O r t h o g o n a l A r c h i t e c t u r e

O v e r a l l W I D E A r c h i t e c t u r e orthogonality Distribution

T r a n s a c t i o n S u p p o r t CORBA OCI

A c t i v e R u l e S u p p o r t

Commercial RDBMS (Oracle 7.2) –Robust basic data support –Flat ACID transactions, basic triggers –Client/Server coupling (OCI) CORBA (ILU) –Flexible distribution –Transparent communication I n f r a s t r u c t u r e

Functionality –Does the system do what was intended? Performance –Does the system offer reasonable performance? Maintainability –Is the system easy to implement and modify? L o o k i n g B a c k a t t h e D e s i g n

Local transaction functionality –Limited flexibility for atomicity control –Limited transactional multi-DB access –X/Open TPM extension helps Rule execution functionality –Decoupled rule execution model –Orthogonal transaction/rule semantics –Limited intra-business transaction rules F u n c t i o n a l i t y i n R e t r o s p e c t

C/S connection to DBMS critical –Large numbers of small transactions –Physical channel creation expensive –Reuse already created channels –Keep channels in channel pool –Modification local to LTI –Further extensions possible: channel creation in idle time statistical forecasting of channel usage P e r f o r m a n c e i n R e t r o s p e c t

Software development in 3 organizations –Sema (ES), POLI (IT), UT (NL) High level of flexibility required Orthogonal architecture design Standard internal module architectures CORBA/IDL interface specification Empty Shell integration Complexity may lead to semantic problems though …. M a i n t a i n a b i l i t y i n R e t r o s p e c t

Transfer of WIDE technology to FORO commercial WFMS (SEMA) Use of transaction concepts in cross- organizational contexts (UT, CrossFlow project) Unbundling of active rule engine functionality for non-WFM purposes (POLI, SEMA) Book on WIDE developments (Kluwer Academic, January ‘99) F u r t h e r D e v e l o p m e n t s