BPMN for REST paper presented at the 3rd International Workshop on BPMN, 21.11.2011, Luzerne, Switzerland

1. BPMN for REST
Cesare Pautasso
Faculty of Informatics, USI Lugano, Switzerland
c.pautasso@ieee.org
http://www.pautasso.info
@pautasso
21.11.2011

2. BPM REST
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3. Business
RESTful
Process
Web Services
Management
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4. WS-* Standards Stack
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5. WS-* Standards Stack
BPM Management
Interoperability
Metadata
Reliability
Transactions
Security
State
Messaging
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6. BPM Management
Interoperability
Metadata
Reliability
Transactions
Security
State
Messaging
Can you do it
with REST?
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7. RESTful APIs…
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8. RESTful APIs…
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9. From REST-*
“ We believe there is huge potential to
marrying REST with workflow and BPM.
http://www.jboss.org/reststar/specifications/workflow.html
[…]
Combined with the architecture of the Web,
a workflow service can provide both a truly
simple, portable, and flexible way to build
workflow driven integrations and
”
applications.
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10. BPM REST
resource resource
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11. REST in one slide
 Web Services expose their
data and functionality trough PUT
resources identified by URI
R
 Uniform Interface constraint: GET
Clients interact with resources POST
through a fix set of verbs. DELETE
Example HTTP:
GET (read), POST (create), PUT (update), DELETE
 Multiple representations for the same resource
 Hyperlinks model resource relationships and valid
state transitions for dynamic protocol description
and discovery
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12. From REST-*
“ We believe there is huge potential to
marrying REST with workflow and BPM.
http://www.jboss.org/reststar/specifications/workflow.html
 The HATEOAS (hypermedia and linking)
principal of REST is logically a dynamic state
machine and fits very well with how
workflow and BPM systems are designed.
 Combined with the architecture of the Web,
a workflow service can provide both a truly
simple, portable, and flexible way to build
workflow driven integrations and
applications.
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13. BPMN Levels
From Bruce Silver
1.Descriptive Modeling
2.Analytical Modeling
3.Executable Modeling
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14. BPMN Primitives
Web
Service Service Task
Web
Service Send/Receive Task
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15. REST as a new connector
RPC BUS
Publish/Subscribe
Call
REST/HTTP
Get/Put/Post/Delete
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16. Outline
1. Goal: use a business process model to:
 orchestrate a set of distributed resources
 specify the behavior of stateful resources
2. BPMN for REST Extension
 Resource Symbol
 Invoking external resources
 Publishing process elements as
resources
3. Examples
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17. Modeling questions
 Which are the resources that a process depends
upon for a successful execution?
 Which are the resources that are affected by the
execution of a process?
 Can we reason about the behavior of stateful
resources using a process model?
 Which are the tasks of a process that have been
made accessible to clients as a resource?
 Which are the possible requests that can be sent
to a resource whose behavior is specified by a
process?
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18. BPMN 2.0 Notation
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19. REST Triangle
Resources Representations
(Multiple,
(Multiple,
Negotiable)
Globally Addressable)
R
(Fixed,
Uniform Interface)
Verbs
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20. Resource Icon
R
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21. Resource Icon and Tasks
Task published as a resource
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22. Resource Icon and Events
Resource Request Event Signal
(BPMN for REST) (BPMN 2.0)
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23. Resource Icon and Data
External Resource
(RESTful Datastore)
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24. Invoking External Resources
GET PUT DELETE POST
Message Flows
(Visualize the semantics
of the HTTP method)
External
Resources:
(Resource lifecycle is
independent
of process instance)
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25. Abstraction
GET message flow Synchronous RPC
with external resource with participant lane
(BPMN for REST) (BPMN)
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26. Publishing X as Resources
Process Task
published as resource published as resource
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27. Publishing X as Resource
SubProcess
published as resource
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28. Publish Process as Resource
List the
GET /process deployed Get a form
processes describing how
GET /process/name to start the
process
Start a new
POST /process/name process
instance Check what
is the state
GET /process/name/instance of the
instance
DELETE /process/name/instance
Clean up
(once it is done)
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29. Publish Task as Resource
List links to the
active tasks
GET /task instances Get a form
describing how
GET /task/name/instance to interact with
the task
Complete a
PUT /task/name/instance
task
Retrieve final
GET /task/name/instance state of task
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30. Publishing X as Resource
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31. Handling Resource Requests
The event models the arrival of a
specific resource request method
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32. Local Search Mashup
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33. Loan Approval Example
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34. RESTBucks Example
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35. Conclusion
 RESTful business process can be modeled using
our simple BPMN for REST notation extension
 Processes interact with external resources
(e.g., Web 2.0 APIs) which are fully decoupled
from their lifecycle
 Processes publish their state as a resource:
 Entire Tasks and SubProcesses
 Use Events to model Resource Requests
 The graphical syntax and extended semantics of
BPMN for REST was only informally sketched,
more work is needed to specify the XML meta-
model for the extension and its formal semantics
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36. 10th International Conference on
Business Process Management
(BPM 2012)
September 3-6 2012, Tallinn, Estonia
http://bpm2012.ut.ee
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37. 16-20 April 2012, Lyon, France
http://ws-rest.org/2012
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38. PhD Positions Available
Cesare Pautasso
http://www.pautasso.info/
@pautasso
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39. Raj Balasubramanians,
Benjamin Carlyle,
Thomas Erl,
Cesare Pautasso,
SOA with REST,
Prentice Hall, 2012
http://soabooks.com/rest/
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