BPMN for REST. Cesare Pautasso Faculty of Informatics, USI Lugano, Switzerland

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1 BPMN for REST Cesare Pautasso Faculty of Informatics, USI Lugano, Switzerland

2 BPM REST Cesare Pautasso 3

3 Business Process Management RESTful Web Services Cesare Pautasso 4

4 WS-* Standards Stack Cesare Pautasso

5 WS-* Standards Stack Interoperability Metadata BPM Reliability Security Management Transactions Messaging State Cesare Pautasso

6 Interoperability Metadata BPM Reliability Security Management Transactions Messaging State Can you do it with REST? Cesare Pautasso 7

7 RESTful APIs Cesare Pautasso 8

8 RESTful APIs Cesare Pautasso 9

9 From REST-* We believe there is huge potential to marrying REST with workflow and BPM. [ ] 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 Cesare Pautasso 10

10 BPM resource REST resource Cesare Pautasso 11

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. 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 DELETE Cesare Pautasso 12

12 From REST-* We believe there is huge potential to marrying REST with workflow and BPM. 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 Cesare Pautasso 13

13 BPMN Levels 1.Descriptive Modeling From Bruce Silver 2.Analytical Modeling 3.Executable Modeling Cesare Pautasso 14

14 BPMN Primitives Web Service Service Task Web Service Send/Receive Task Cesare Pautasso 15

15 REST as a new connector RPC Call BUS Publish/Subscribe REST/HTTP Get/Put/Post/Delete Cesare Pautasso 16

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 Cesare Pautasso 17

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? Cesare Pautasso 18

18 BPMN 2.0 Notation Cesare Pautasso 19

19 REST Triangle Resources (Multiple, Globally Addressable) Representations (Multiple, Negotiable) R (Fixed, Uniform Interface) Verbs Cesare Pautasso 20

20 Resource Icon R Cesare Pautasso 21

21 Resource Icon and Tasks Task published as a resource Cesare Pautasso 22

22 Resource Icon and Events Resource Request Event Signal (BPMN for REST) (BPMN 2.0) Cesare Pautasso 23

23 Resource Icon and Data External Resource (RESTful Datastore) Cesare Pautasso 24

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) Cesare Pautasso 25

25 Abstraction GET message flow with external resource (BPMN for REST) Synchronous RPC with participant lane (BPMN) Cesare Pautasso 26

26 Publishing X as Resources Process published as resource Task published as resource Cesare Pautasso 27

27 Publishing X as Resource SubProcess published as resource Cesare Pautasso 28

28 Publish Process as Resource GET GET POST GET /process /process/name /process/name List the deployed processes /process/name/instance DELETE /process/name/instance Get a form describing how to start the process Start a new process instance Check what is the state of the instance Clean up (once it is done) Cesare Pautasso 29

29 Publish Task as Resource GET GET /task /task/name/instance List links to the active tasks instances Get a form describing how to interact with the task PUT GET /task/name/instance /task/name/instance Complete a task Retrieve final state of task Cesare Pautasso 30

30 Publishing X as Resource Cesare Pautasso 31

31 Handling Resource Requests The event models the arrival of a specific resource request method Cesare Pautasso 32

32 Local Search Mashup Cesare Pautasso 33

33 Loan Approval Example Cesare Pautasso 34

34 RESTBucks Example Cesare Pautasso 35

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 metamodel for the extension and its formal semantics Cesare Pautasso 36

36 10 th International Conference on Business Process Management (BPM 2012) September , Tallinn, Estonia Cesare Pautasso 37

37 16-20 April 2012, Lyon, France Cesare Pautasso 38

38 PhD Positions Available Cesare Pautasso 2011 Cesare Pautasso 39

39 Raj Balasubramanians, Benjamin Carlyle, Thomas Erl, Cesare Pautasso, SOA with REST, Prentice Hall, Cesare Pautasso 40