BPMN for REST
Description
BPMN for REST paper presented at the 3rd International Workshop on BPMN, 21.11.2011, Luzerne, Switzerland
Transcript
BPMN for RESTCesare PautassoFaculty of Informatics, USI Lugano, Switzerlandc.pautasso@ieee.orghttp://www.pautasso.info@pautasso21.11.2011 BPM REST©2010 – Cesare Pautasso 3 Business RESTful Process Web Services Management©2010 – Cesare Pautasso 4 WS-* Standards Stack©2009-2010 – Cesare Pautasso – 30.6.2010 5 WS-* Standards Stack BPM Management Interoperability Metadata Reliability Transactions Security State Messaging©2009-2010 – Cesare Pautasso – 30.6.2010 6 BPM Management Interoperability Metadata Reliability Transactions Security State Messaging Can you do it with REST?©2010 – Cesare Pautasso 7 RESTful APIs…©2011 – Cesare Pautasso 8 RESTful APIs…©2011 – Cesare Pautasso 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.©2011 – Cesare Pautasso 10 BPM REST resource resource©2010 – Cesare Pautasso 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©2011 – Cesare Pautasso 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.©2011 – Cesare Pautasso 13 BPMN Levels From Bruce Silver 1.Descriptive Modeling 2.Analytical Modeling 3.Executable Modeling©2011 – Cesare Pautasso 14 BPMN Primitives Web Service Service Task Web Service Send/Receive Task©2011 – Cesare Pautasso 15 REST as a new connector RPC BUS Publish/Subscribe Call REST/HTTP Get/Put/Post/Delete©2010 – Cesare Pautasso 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©2011 – Cesare Pautasso 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?©2011 – Cesare Pautasso 18 BPMN 2.0 Notation©2011 – Cesare Pautasso 19 REST Triangle Resources Representations (Multiple,(Multiple, Negotiable)Globally Addressable) R (Fixed, Uniform Interface) Verbs©2011 – Cesare Pautasso 20 Resource Icon R©2011 – Cesare Pautasso 21 Resource Icon and Tasks Task published as a resource©2011 – Cesare Pautasso 22 Resource Icon and Events Resource Request Event Signal (BPMN for REST) (BPMN 2.0)©2011 – Cesare Pautasso 23 Resource Icon and Data External Resource (RESTful Datastore)©2011 – Cesare Pautasso 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)©2011 – Cesare Pautasso 25 Abstraction GET message flow Synchronous RPC with external resource with participant lane (BPMN for REST) (BPMN)©2011 – Cesare Pautasso 26 Publishing X as Resources Process Task published as resource published as resource©2011 – Cesare Pautasso 27 Publishing X as Resource SubProcess published as resource©2011 – Cesare Pautasso 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)©2010 – Cesare Pautasso 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©2010 – Cesare Pautasso 30 Publishing X as Resource©2011 – Cesare Pautasso 31 Handling Resource Requests The event models the arrival of a specific resource request method©2011 – Cesare Pautasso 32 Local Search Mashup©2011 – Cesare Pautasso 33 Loan Approval Example©2011 – Cesare Pautasso 34 RESTBucks Example ©2011 – Cesare Pautasso 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©2011 – Cesare Pautasso 36 10th International Conference on Business Process Management (BPM 2012) September 3-6 2012, Tallinn, Estonia http://bpm2012.ut.ee©2010 – Cesare Pautasso 37 16-20 April 2012, Lyon, France http://ws-rest.org/2012©2010 – Cesare Pautasso 38 PhD Positions Available Cesare Pautasso http://www.pautasso.info/ @pautasso©2011 Cesare Pautasso 39 Raj Balasubramanians, Benjamin Carlyle, Thomas Erl, Cesare Pautasso, SOA with REST, Prentice Hall, 2012 http://soabooks.com/rest/©2011 – Cesare Pautasso 40
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