BPEL2oWFN User's Manual
About this document:
This manual is for BPEL2oWFN, Version 1.2, a
tool translating a web service described in BPEL into
an open workflow net (oWFN), last updated 6 April 2006.
This manual does not explain how to setup or install
BPEL2oWFN. For this information please read the
Installation Manual which is part of the distribution or can be
downloaded from the website of BPEL2oWFN
Copyright © 2005, 2006 Niels Lohmann
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
BPEL2oWFN is licensed under the GNU General
Copyright © 2005, 2006 Niels Lohmann, Christian Gierds
and Dennis Reinert.
BPEL2oWFN is part of the Tools4BPEL project
funded by the Bundesministerium für Bildung und Forschung. See
http://www.informatik.hu-berlin.de/top/tools4bpel for details.
BPEL2oWFN is a compiler translating a business processes expressed in
BPEL (Business Process Execution Language for Web Services)
[ACD^+03] into an oWFN (open Workflow Net) [MRS05].
This oWFN can be used to:
- check controllability [Mar03, Wei04] with Fiona [Fiona],
- generate the operating guidelines [MRS05] with Fiona [Fiona],
- check for deadlocks, or
- check any temporal logic formula with several model checking tools [LoLA, MCK].
BPEL2oWFN uses static analysis to make the generated oWFN
as compact as possible to analyze a chosen property. This is called
flexible model generation (see Future Work).
BPEL2oWFN is the successor from BPEL2PN [SHS05], a
Java-based compiler generating low-level Petri nets. BPEL2oWFN can be
understood as a re-implementation for extensibility and performance issues. Its
functionality is a superset of the functionality of BPEL2PN.
BPEL2oWFN was written by Niels Lohmann, Christian Gierds
and Dennis Reinert. It is part of the Tools4BPEL project
funded by the German Bundesministerium für Bildung und Forschung. See
http://www.informatik.hu-berlin.de/top/tools4bpel for details.
1.2 Translation Process
The translation process of the BPEL business process is performed in
six steps which we describe briefly in this section:
- Lexical and syntactical analysis. BPEL2oWFN parses the
input process according to the specification of BPEL4WS version 1.1
[ACD^+03]. All information about the process is collected in a symbol
table for further use.
- Semantic analysis. The input file is checked against the constraints
of the specification, e.g. that each defined link has to be used as source and
target exactly once. BPEL processes violating these constraints are
- AST generation. For further analysis steps the exact syntax
(indentation etc.) is not used any more. The input process is represented as
an AST (abstract syntax tree). While generating the AST, the
implicit transformation rules of BPEL (e.g. the presence of an
otherwise-branch with an empty activity) are applied.
- Net generation. The nodes of the AST are used to create
the Petri net using the pattern database by applying `unparse'-rules (rules
associating each node with a pattern).
- Net optimization (optional). To reduce the generated net several
structural reduction rules can be applied, e.g. to merge sequences.
- Net output. The generated Petri net can be exported in several file
1.3 Concepts of BPEL2oWFN
In this section we describe the main concepts of BPEL2oWFN used to
realize the translation. Reading this section is not necessary for using
BPEL2oWFN, yet knowing the underlying algorithms and data structures
not only helps to locate bugs, but also helps you to customize
BPEL2oWFN or request a feature.
1.3.1 Abstract Syntax Tree
The AST (abstract syntax tree) is an abstraction of the
syntax tree generated while parsing the BPEL process: any
unnecessary information (e.g. indention, brackets or other
“syntax-supporting” elements) is omitted. It is the central data
structure of BPEL2oWFN. The nodes of the AST are
annotated with pointers to symbol table entries during the analysis steps.
These annotations are used to select the most compact Petri net pattern
from the pattern database to check a given property.
1.3.2 Pattern Repository
The idea of flexible model generation is to find the most compact
model to check a given property. The patterns of the Petri net
semantics of [Sta05] are designed to fit in any given context.
However when the context is known some behavior modeled in the
patterns (i.e. some of the nodes) can be safely removed without
changing its semantics. BPEL2oWFN is designed to hold
several sets of Petri net patterns each suitable in certain
contexts. These patterns are collected in a pattern repository.
1.3.3 Petri Net Class
BPEL2oWFN provides many algorithms and data structures to
build, represent, modify and simplify Petri nets and open workflow
nets, resp. They are the interface between the pattern database and
the file output for the model checking tool. The functions are
collected in an extensible class allowing to add more output file
formats, structural simplification rules (optimized to preserve certain
properties such as deadlock freedom or liveness) or abstractions
(e.g. abstraction from variables, abstraction from external behavior).
1.3.4 Control Flow Graph
Beside the dynamic analysis of the generated Petri net model with Fiona
or classical model checking tools, BPEL2oWFN prototypically
implements a control flow graph (CFG) (c.f. [Hei03]). This CFG can
be used to check most of the constraints of the specification statically,
i.e. without actually deploying and running the BPEL process. For example,
the CFG can be used to check if each variable is initialized by an
incoming message or an
2 Invoking BPEL2oWFN
The standard invocation of BPEL2oWFN is:
bpel2owfn -i inputfile.bpel -f owfn -o
where inputfile.bpel is a BPEL process. The option
-f owfn cause BPEL2oWFN to generate an open workflow net. This
net is written to a file named inputfile.owfn, because of the option
-o. For more examples, see Examples.
BPEL2oWFN can be called without any parameter. In this case, it acts
as a simple parser for BPEL, that reads its input from the standard input
BPEL2oWFN supports the following command-line options:
- Print an overview of the command-line options and exit.
- Print version information and exit.
- -i filename.bpel
- Read BPEL input from file filename.bpel.
If this parameter is omitted, input is read from standard input (
- The generated files are written to a file called filename. If the short
form is used or the filename is omitted, the input file name is taken and
extended by the suffix of the chosen file format(s). If this parameter is
omitted, the output is passed to the standard output (
- All additional information like warnings and processing information
are written to a file called filename. If the short form is used
or the filename is omitted, the output file name is taken and
extended by the suffix .log. If this parameter is omitted, the
information is passed to the standard error output (
- --debug=1-4 | flex | bison
- -d 1-4 | flex | bison
- This option triggers different debug levels, and can enable additional
information from Flex and Bison about how the input is lexed and parsed.
- This option makes BPEL2oWFN behave like its predecessor,
BPEL2PN: it generates a Petri net LoLA format and an
information file. The option --bpel2pn is a shortcut for
--mode=petrinet --format=lola --format=info --output.
When invoking BPEL2oWFN several modes are possible.
Please note that you can only use at most one mode.
- -m modus
BPEL2oWFN supports four different modes for handling
BPEL, so modus can be one of the following options:
- Outputs the AST (abstract syntax tree) generated while
parsing the input file to standard output. This option is mostly
used for debugging reasons since it shows the implicit transformations
and the phylum names used when generating the Petri net.
- For control flow analysis (a form of static analysis) a CFG (Control
Flow Graph) is generated. It can be printed in graphical (dot)
representation. This option is in an early beta-stage and can only check
for uninitialzed variables yet. For more information, see Future Work.
- Generates a Petri net representing the semantics of the given
process. Other options can be added to simplify or modify that generated Petri
net (see below).
- Outputs the parsed BPEL file in XML representation. Any
unnecessary attributes are omitted. This option is mostly used for debugging
reasons as it shows the implicit transformations and the identifiers of the
2.1.2 Additional parameters
These options control some Petri net-related options. See Petri Net-related Functions for more details.
- -p par
- When the parameter is set, the pattern for the message event handler is
cyclic as depicted in Fig. 30/31 of [Sta05]. If the parameter is not set
(standard case), the pattern is acyclic: the activity embedded in the
event handler is executed at most once, depended on the incoming messages.
- When the parameter is set, the pattern for the
<while> activity is
cyclic as depicted in Fig. 18 of [Sta05]. If the parameter is not set
(standard case), the pattern is acyclic: the activity embedded in the
<while> activity is at most executed once, chosen non-deterministically.
- Add an extra loop transition to the final place of the generated Petri net to
live-lock the system in order to find deadlocks.
- With this parameter, standard faults may not occure in activities directly nested
in a fault handler.
- When the parameter is set, only used-defined faults using the
activity can occur.
- Removes places of the generated Petri net modelling variables as well as the
place modelling the system clock.
- Structurally simplify the generated Petri net.
If you want to enable more than one parameter you have to add -p/
--parameter to each parameter.
2.1.3 Output formats
Especially for the Petri net mode, a variaty of output formats are supported,
see File Formats for more information. There are invoked by the
- -f fileformat
- Create a Petri net in APNN (Abstract Petri Net Notation). Implies the
- Create a dot representation of the structure generated in the current mode
which can be any kind of Petri net (mode petrinet or the control flow
graph (mode cfg).
- Create an additional information file. Implies the mode petrinet.
- Create a LoLA place/transition net. Implies the mode
- Create a low-level oWFN in Fiona file format. Implies the
- Create a Petri net in low-level PEP notation. Implies the mode
- Create a PNML Petri net. Implies the mode petrinet.
- Create an XML (Extensible Markup Lanuage) file. Implies the mode
If you want to use more than one output file format you have to add -f/
--fileformat to each file format. Please note that the underlying modes
of the given file formats are the same, i.e. you cannot create XML and
LoLA files together since XML uses the mode pretty
whereas LoLA uses the mode petrinet.
In this section we show some examples how BPEL2oWFN can be
- bpel2owfn -i sample.bpel -flola -finfo -o -p simplify
Reads the file sample.bpel, generates a structural simplified
low-level Petri net and saves it in a LoLA file
sample.lola. For further information a file
sample.info is generated.
- bpel2owfn -i sample.bpel -fowfn -d3 -o
Reads the file sample.bpel, generates a low-level open
workflow net and saves it in an oWFN file
sample.owfn. For further information a file
sample.info is generated. During the conversion several debug
messages are printed to standard output.
- prog | bpel2owfn -fdot -m petrinet | dot -Tpng -osample.png
Runs the program prog and reads its output as BPEL
process, generates a Petri net and outputs its Dot representation.
This stream is read by Dot which layouts the Petri net and creates an output
PNG (Portable Network Graphic) file sample.png.
- bpel2owfn -i sample.bpel -m ast
Reads the file sample.bpel and prints the abstract syntax tree
(AST) to standard output.
2.3 Exit Values
When BPEL2oWFN is invoked and run without any error, the
exit value is 0.
- No error. The input file could be correctly opened, parsed and
the output file(s) could be generated without any error.
- Lexical or syntax error. This error occurs while lexing or
parsing the input file. It is thrown by the lexer or the parser,
resp. Usually the `source' of the error (i.e. the filename and line
number) is indicated together with the unexpected (last read) and
Error while parsing
syntax error, unexpected X_SLASH, expecting X_OPEN
Error in `example.bpel' in line 12:
token/text last read was `/'
Please note that the indicated position (i.e. the line number) may
be fuzzy — it should be understood as a hint to the erroneous
- `File not found' exception. The given input file was not found
resp. could not be opened.
An error has occurred while parsing "example.bpel"!
Exception #2 occurred!
File `example.bpel' not found.
- `File could not be opened' exception. An output file could not be opened
for write access. You may check the appropriate for the target directory or the
file if it already exists.
An error has occured while parsing "example.bpel"!
Exception #3 occured!
File "example.dot" could not be opened for writing access!
- Option mismatch. The given command-line options cannot be
An error has occurred while parsing "example.bpel"!
An error has occured while parsing "<STDIN>"!
Exception #10 occured!
Choose only one mode
Type ./bpel2owfn -h for more information.
- `Dynamic cast error' exception. While building an internal scope
tree an unexpected error has occurred.
- Node not found.
- `Node already defined' exception. While generating the Petri net
a node was found having a history entry covered by another node
An error has occurred while parsing "example.bpel"!
Exception #41 occurred!
Place with role `1.internal.final' already defined.
- `Merging error' exception. While generating the Petri net an
error occurred while merging two nodes. It happens either when one
of the nodes was not found or one of the nodes is a guarded
transition—the merging of guarded transitions is not yet
- `Arc error' exception. While generating the Petri net an error
occurred while adding an arc to the net. It happens either on type
errors — i.e. an arc between two transitions (or two places, resp.)
should be drawn — or when the source or target node of an arc was
Please report the occurrence of any exception with numbers 30–50
since it indicates a bug in BPEL2oWFN we would like to fix
immediately (see Reporting Bugs).
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,
- 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,
- 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].
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:
ID TYPE ROLES
a list of places
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:
- Each BPEL activity has been assigned an identifier during the
syntactic analysis of the input process. Each node added to the Petri net
from the Petri net pattern of that activity begins with that identifier.
For example, BPEL's activity process has the identifier 1,
so that all nodes of the process pattern begin with 1.. To find out the
identifiers of a given process use the --xml command-line option which
prints the id of each activity as an XML attribute.
- In most cases each BPEL activity can be source or target of
links. The semantics defined in [Sta05] organizes this link concept by several
wrappers. For an activity with the identifier id the nodes of the wrapper
begin with id. whereas the nodes of the actual activity begin
- The roles of nodes of the stop pattern of a process or scope with
identifier id begin with id.internal.stop..
The same schema is used for fault handlers
(id.internal.faultHandler.), compensation handlers
(id.internal.compensationHandler.) and event handlers
- Labels (e.g. initial) in a figure of [Sta05] are appended to the
id string (e.g. id.internal.initial). If both numeric (e.g.
p1) and textual (e.g. initial) labels are depicted in a figure,
the latter is used.
- The labels of fault-throwing transitions also contain the last place of
the positive control flow: If, for example, a reply activity throws a fault,
the fault-throwing transition reads from the place labeled
id.internal.running and is labeled
- In parameterized patterns (e.g. an assign activity or all structured
activities) the labels of the figures of [Sta05] are trailed by an numeration
3.3 Dot Graphics
To bugfix2 the implemented Petri net patterns
BPEL2oWFN implements a graph representation of the generate Petri
net. Furthermore, the CFG can be printed as dot output.
4 Petri Net Patterns
In version 1.2 of BPEL2oWFN the following Petri net
patterns are implemented:
4.1 Petri net semantics from [Sta05]
The Petri net semantics for BPEL4WS from Christian Stahl
(Humboldt-Universität zu Berlin) published in [Sta05].
Feature complete semantics covering both positive control flow with
event handling and negative control flow (fault and compensation
4.1.2 Limitations of the semantics
- Only one instance of a BPEL process can be
transformed into a Petri net.
- The semantics abstracts from the connection of a
BPEL process to its partner processes. The interface of a
BPEL process is transformed into a set of message
channels, i.e. places in the Petri net.
- In our Petri net patterns we model data, but we abstract from
the definition of the functions which edit the data. Furthermore, we
did not specify the transition guards and so we did not specify
which circumstances are necessary that a specific fault can occur.
- Every activity is limited to one correlation set (except the
synchronous invoke which is limited to two correlation sets).
4.1.3 Changes and Modulation
We tried to stick as close to the Petri net patterns of [Sta05] as
possible. However, the implemented patterns in the pattern database
sometimes differ to the given patterns due to discovery of bugs or
implementation decisions. In this subsection we sum up these changes
to help you understand the generated Petri net model.
- Fault model. At most one error can occur in the positive
control flow of each scope or process. Yet this confines the
possible runs of the process it is only a little change of the
semantics, since — according to the specification — only the
first fault is handled anyway. While further faults occurring before
the positive control flow is stopped are ignored in the original
semantics of [Sta05] (in fact, the faults are collected on place
fault_in and then consumed by a reset arc) they are prevented
in the implemented semantics. In our model, exactly the first
occurring fault is handled, whereas in [Sta05] one fault is chosen
Furthermore, all failed places of the activities were
removed. In the original Petri net semantics, all faults of a scope
were collected on the fault_in of the stop-pattern and then
classified as being the first fault of the scope, a following fault,
a fault from the fault handler, a fault from the compensation
handler, or a fault from a child scope. In our implementation, new
places (fh_fault_in and ch_fault_in) were introduced
and each activity throws its faults to the “correct” place
To ensure that at most one error can occur (i.e. at most one token
is produced on any fault place) the fault places are guarded by
state places: To throw a fault from an activity enclosed in a scope,
the state of that scope has to be Active. The first thrown
fault changes the state to !Active thus preventing more
faults to occur. The places fh_fault_in and
ch_fault_in, resp. are guarded by
Moreover, the generated Petri nets have less nodes than those
generated by BPEL2PN [SHS05] since an unfolding of the
reset arcs in not necessary any more.
- Standard faults. The “throw-fault” and “stop” transitions
are generated using parametrized functions. With the command-line parameter
--parameter=nostandardfaults all BPEL standard faults
that can occur in the activites (i.e. all faults except user-defined faults
in a throw activity or join failures) are suppressed. The generated models
have a smaller state space and allow the analysis for controllability
which is impossible without the assumption that messages can always be
In order not to suppress standard faults at all, the command-line parameter
--parameter=nofhfaults can be used to allow standard faults outside
fault handlers, i.e. to create models that allow the occurrence of one
standard fault in each scope yet disallow to occurrence of further faults.
- 1-safety. The new modeling of the fault management yields
to 1-safe Petri nets (i.e. any reachable state of the Petri net
model puts at most one token on each place of the net).
Beside performance (e.g. only 1 bit is needed to store the marking
of a place) and compatibility issues (e.g. 1-safety is a
prerequisite to use the Model-Checking Kit [MCK]), features not
supported by the Petri net semantics can be discovered since the
generated net will most likely violate 1-safety when an unsupported
BPEL feature is used. If, for example, a scope is enclosed
in a while loop (which would model instantiation which is not
supported by the Petri net semantics Limitations of the semantics), the state places of that scope would not be 1-safe.
- Assign activity. All copy branches of an assign activity
are modeled in a single pattern (i.e. Fig. 6 and Fig. 7 are merged).
Furthermore, when an error (outside that activity) occurs, an active
assign-activity is not stopped until all copy branches have
finished. This is described in [ACD^+03] as:
The assign activities are sufficiently short-lived that they are allowed to
complete rather than being interrupted when termination is forced.
This change fixes a bug in the Petri net semantics.
- While activity. Since the original semantics does not support
instances of the BPEL process, while activities were poorly supported and
usually produced non 1-safe Petri nets or deadlocks as links embedded in
the while activity were evaluated incorrectly. In the implementation the
while activity is acyclic: the embedded activity is now executed at most
once (whether or not it is executed is decided non-deterministically).
The “original” behavior can be restored with the command-line parameter
- Event handlers. There is one pattern for both alarm and
message event handlers (i.e. Fig. 29 and Fig. 30 are merged). When
no event handler is specified, an “implicit” event handler is
installed which is just a stub and does not change the semantics. The
message event handlers are acyclic by default to create acyclic Petri net
models. However, the “original” behavior can be restored with the
command-line parameter --parameter=cycliceh.
- Deadlocks. A transition named 1.internal.finalloop
can be added to livelock the process upon completion using the command-line
parameter --parameter=finalloop. This leads to
deadlock-free Petri nets in case of processes with “reasonable”
control flow and helps to find unwanted deadlocks occurring due
wrong modeling. If, for example, the links of a process model are
cyclic the generated Petri net will deadlock.
In future versions of BPEL2oWFN these found deadlocks
shall be mapped back into the BPEL code to highlight the
“unreasonable” activities (i.e. a cycle-closing link).
- Unfoldings of high-level places. Due to the abstraction (high-level to
low-level) of the patterns some places were unfolded: the place
compScope of Fig. 42–44 usually holding a token with a name
of a scope is unfolded to compScope.scopename and only
merged with the ch_in-place of that respective scope. In all
other cases the places are “converted” to low-level places so the
generated model completely abstracts from data.
- Link semantics. The generated Petri net model always
generates negLink places for structured activities
independently of the presence of links. Anyway, the semantics is not
changed since the resulting subnets are dead in this case.
- Correlation sets. Correlation sets are not implemented and
are simply ignored during parsing.
5 Petri Net-related Functions
Currently implemented Petri net-specific functions:
5.1 Structural Simplification
- If two transitions t_1 and t_2 have the same
preset and postset, one of them can be removed.
- If a transition has a singleton preset and postset, the
transition can be removed (sequence) and the preset and postset can
- All places with empty preset and postset (isolated places) are
These structural reduction rules are implemented in the command-line option
--parameter=simplify, see Invoking BPEL2oWFN). To acheive a
better reduction, combine the parameter with --parameter=novarialbles.
- To obtain a place/transition Petri net from an open workflow
net the communication places are removed. This abstraction from
communicational behavior is used in all Petri net output formats
except oWFN (--format=owfn).
- The original Petri net semantics [Sta05] consists of high-level
Petri net patterns. However, the models generated from BPEL2oWFN
abstract from data. Therefore all transition guards, arc inscriptions
and arc types were “converted” to low-level constructs: all
transition guards and arc inscriptions were removed (decisions are
now made non-deterministically) and read arcs are “unfolded” to
loops. Due to a new fault management (see Changes and Modulation) the patterns do not contain any reset arcs and is 1-safe.
The following places are initially marked to ensure a deadlock-free
model of processes with “reasonable” control-flow (e.g. with an
acyclic link structure):
- the initial place of the process (1.internal.initial),
- the variable places (variable.variablename), and
- the clock (1.internal.clock) if the process embeds an
alarm event handler or a
6 Limitations and Bugs
6.1 Known Bugs
As this is the first public version of BPEL2oWFN the
translation from a BPEL process to an open workflow net
might be unstable or incorrect in some few scenarios:
- Problem: The original semantics of [Sta05] was created to
support executable BPEL processes. Therefore the
translation of abstract BPEL processes (business
protocols) might throw an exception or even crash.
Solution: Each communicating activity (i.e.
reply) should be defined with (input/output)
- Problem: The parser of BPEL2oWFN is not capable
of skipping XML elements originating other namespaces than
bpws'. Processes using these elements are rejected with a
syntax error message.
Solution: Try removing or commenting these elements.
- Problem: LoLA does not accept the generated files and
reports parse errors in the first line.
Solution: This problem occurs using a pre-compiled windows version
of BPEL2oWFN. The generated files are in Windows format, yet
LoLA only supports files in Unix format. To overcome this
limitation of LoLA, use a tool like dos2unix or
change the file format in an editor like vi.
6.2 Reporting Bugs
If you find a bug in BPEL2oWFN, please first check that it
is not a known bug listed in `Known Bugs'. Otherwise please send us
an electronic mail to email@example.com.
Include the version number which you can find by running
bpel2owfn --version. Also include in your message the input
BPEL process and the output that the program produced. We
will try to answer your mail within a week.
If you have other questions, comments or suggestions about
BPEL2oWFN, contact us via electronic mail to
6.3 Contact Person
Humboldt-Universität zu Berlin
Institut für Informatik
Unter den Linden 6
10099 Berlin, Germany
- (+49) (30) 2093-3070
- (+49) (30) 2093-3067
7 Future Work
For future releases of BPEL2oWFN the following features are planned:
- Add data aspects. In the implemented patterns we abstract
from data and do not evaluate join or transition conditions. Instead all
decisions are made non-deterministically. With static analysis it is
possible to find the relevant ranges of values that allow a replacement
of non-deterministic choices with choices made evaulating data. This
technique (called abstract interpretation) might help to reduce the
modelled behavior of the process yet being more precise.
- Control flow analysis. In [Hei03] a control flow graph for
BPEL was introduced. This control flow graph (currently
implemented prototypic) is the base for more sophisticated analysis,
e.g. finding unreachable activities, uninitialized variables or
other problems that can occur during runtime.
- Detailed info-files. The generated info-files currently just
list the nodes of the generated net. To help the retranslation of Petri
net-specific properties to the input process the generated files have
to be more detailed. The integration of a symbol table is currently
in pre-beta state and should be finished in the next version of
- Support for WS-BPEL. The specification of
WS-BPEL (Web Service Business Process Execution Language)
version 2.0 is in its final phase. As soon as the standardization is
completed, WS-BPEL can be supported by BPEL2oWFN
by overworking the grammar and adding appropriate patterns to the
Appendix A References
- Tony Andrews, Francisco Curbera, Hitesh Dholakia, Yaron Goland, Johannes Klein,
Frank Leymann, Kevin Liu, Dieter Roller, Doug Smith, Satish Thatte, Ivana
Trickovic, and Sanjiva Weerawarana. Business Process Execution Language for
Web Services, Version 1.1. Technical report, BEA Systems, IBM, Microsoft, SAP,
Siebel Systems. May 2003.
- Falko Bause, Peter Kemper, and Pieter Kritzinger. Abstract Petri Net
Notation. Petri Net Newsletter 49:9-27, October 1995.
- Peter Massuthe and Daniela Weinberg. Fiona.4
- Thomas Heidinger. Statische Analyse von BPEL4WS-Prozessmodellen (in German).
Studienarbeit, Humboldt-Universität zu Berlin, December 2003.
- Karsten Schmidt. LoLA: A Low Level Analyser. Manual.
- Axel Martens. Verteilte Geschäftsprozesse – Modellierung und Verifikation
mit Hilfe von Web Services (in German). PhD thesis, Humboldt-Universität
zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2003.
- Javier Esparza, Claus Schröter, and Stefan Schwoon. Model-Checking Kit.
- Peter Massuthe, Wolfgang Reisig, and Karsten Schmidt. An Operating Guideline
Approach to the SOA. Proceedings of the 2nd South-East European Workshop on
Formal Methods 2005 (SEEFM05), Ohrid, Republic of Macedonia, 2005.
- University of Oldenburg, Department of Computing Science. PEP (Programming Environment based on Petri Nets). Manual.
- Karsten Schmidt. LoLA: A Low Level Analyser. In: Mogens Nielsen,
and Dan Simpson, editors: Application and Theory of Petri Nets, 21st
International Conference (ICATPN 2000), pp. 465-474, Springer-Verlag
(LNCS 1825), June 2000.
- Sebastian Hinz, Karsten Schmidt, and Christian Stahl. Transforming BPEL to
Petri Nets. In W.M.P. van der Aalst, B. Benatallah, F. Casati, and F. Curbera,
editors, Proceedings of the Third International Conference on Business
Process Management (BPM 2005), pp. 220-235, Springer-Verlag
(LNCS 3649), September 2005.
- Christian Stahl. A Petri Net Semantics for BPEL.
Informatik-Berichte 188, Humboldt-Universität zu Berlin, July 2005.
- Daniela Weinberg. Analyse der Bedienbarkeit. Diplomarbeit,
Humboldt-Universität zu Berlin, October 2004.
- Michael Weber and Ekkart Kindler. The Petri Net Markup Language. In: Hartmut Ehrig,
Wolfgang Reisig, Grzegorz Rozenberg, Herbert Weber, editors: Petri Net Technology for
Communication-Based Systems: Advances in Petri Nets, pp. 124-144, Springer Verlag
(LNCS 2472), January 2003.13
Appendix B GNU General Public License
Version 2, June 1991
Copyright © 1989, 1991 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The licenses for most software are designed to take away your
freedom to share and change it. By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software—to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
- This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The “Program,” below,
refers to any such program or work, and a “work based on the Program”
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language. (Hereinafter, translation is included without limitation in
the term “modification.”) Each licensee is addressed as “you.”
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.
- You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.
- You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
- You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
- You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.
- If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License. (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
- You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
- Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,
- Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,
- Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
- You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.
- You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
- Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
- If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all. For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
- If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
- The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and “any
later version,” you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
- If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this. Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.
- BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.
- IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and an idea of what it does.
Copyright (C) 19yy name of author
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 20yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'. This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
The hypothetical commands show w and show c should show
the appropriate parts of the General Public License. Of course, the
commands you use may be called something other than show w and
show c; they could even be mouse-clicks or menu items—whatever
suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a “copyright disclaimer” for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.