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3 File Formats

BPEL2oWFN can generate several file formats:

3.1 Petri Net File Formats

These file formats output the generated Petri net model to various Petri net file formats to support as much model checking and analysis tools as possible. The nodes of the Petri net are named using the internal (numeric) names generated by BPEL2oWFN. For more information on the node naming conventions of BPEL2oWFN, see Naming Conventions.

In all file formats, the inital place of the process, the process clock and all variable places are initially marked.

LoLA place/transition net
A (low-level) place/transition net as described in [LoLA]. The first entry of the history of each node is added as a comment.
oWFN in Fiona format
An open workflow net is a Petri net with an interface, i.e. two sets of places: input places and output places. Additionally an open workflow net has a set of final markings. To represent oWFNs the LoLA format was extended to implement this categorization.
Petri Net Markup Language (PNML)
A (low-level) place/transition net in Petri Net Markup Language as described in [WK02]. An arcname value is just added to meet the syntactic requirements and is just an enumeration of the arcs (a1, a2, ...).
Abstract Petri Net Notation (APNN)
A (low-level) place/transition net in Abstract Petri Net Notation as described in [BKK95]. An arcname value is just added to meet the syntactic requirements and is just an enumeration of the arcs (a1, a2, ...).
Low-level PEP Notation
A (low-level) place/transition net in low-level PEP (Programming Environment based on Petri Nets) notation as described in [PEP].

3.2 Info-files

The Info-files are generated when any command-line option is used which imply Petri net-generation. When reading from a file process.bpel a file process.info is generated. This file sums up all places and transitions together with their internal (numeric) name and their complete history:

     PLACES:
     ID  TYPE        ROLES
     a list of places
     
     TRANSITIONS:
     ID      ROLES
     a list of transitions

These files are generated to document the connection between the generated output file and the chosen Petri net patterns. In future distributions of BPEL2oWFN the Info-files will be used to annotate witness and counter-example paths, resp. and to “re-translate” Petri net properties (e.g. a dead transition) to the input BPEL process.

3.2.1 Naming Conventions

BPEL2oWFN generates the output Petri net by creating and merging parameterized patterns of the Petri net semantics defined in [Sta05]. Due to merging and simplifying the Petri net nodes “belong” to more than one pattern. For example, in a sequence the initial place of the sequence and the initial place of its first activity are merged so that the final Petri net contains one place with two roles.

The roles of each place are collected during the Petri net generation. They form the history of the node. It is used to locate errors of the modeled business process: If, for example, BPEL2oWFN generates a Petri net of a business process and the model checker LoLA finds a dead transition, its history helps to find which BPEL constructs are affected and in this case will never be executed.

The roles are named using the following conventions:

3.3 Dot Graphics

To bugfix1 the implemented Petri net patterns BPEL2oWFN implements a graph representation of the generate Petri net. Furthermore, the CFG can be printed as dot output.


Footnotes

[1] The Petri nets usually have a large number of nodes so that the graphical representation of a `real world' process would not be suitable to process, read or understand. That is why the Dot output shall be seen as a means to debug small patterns.