RESTful Business Process Management
Cesare Pautasso
http://www.pautasso.info
[email protected]
@pautasso
University of Lugano (USI)
Faculty of Informatics
- Opened 2004
- 30 Professors
- 150+ PhD/Postdoc researchers
- New Software Institute
- New Master in Software and Data Engineering
Architecture, Design and Web Information Systems Engineering
- BenchFlow - a benchmark for workflow engines
- Liquid.js - Liquid Software Architecture
- ASQ - Interactive Web Lectures
- Parallel JavaScript/Multicore Node.JS
- SAW - Collaborative Architectural Decision Making
- NaturalMash - Web Service Composition with Natural Language
Towards RESTful BPM
- BPEL for REST [BPM2008]
- RESTful Web Service Composition with BPEL for REST [JDKE2009]
- Composing RESTful Services with JOpera [SC2009]
- Push-enabling RESTful Business Processes [ICSOC2011]
- BPMN for REST [BPMN2011]
- RESTful Business Process Management in the Cloud [PESOS2013]
- Control flow patterns for decentralized RESTful composition [TWEB2013]
- Atomic Distributed Transactions: a RESTful design [WS-REST2014]
- A conversation based approach for modeling REST APIs [WICSA2015]
- Modeling RESTful Conversations with extended BPMN Choreography Diagrams [ECSA2015]
- From Choreography Diagrams to RESTful Interactions [WESOA2015]
- Visual Modeling of RESTful conversations with RESTalk [JSOSym2016]
- A Pattern Language for RESTful Conversations [EuroPLOP2016]
Decoupled Sharing
Hypermedia
Discovery by Referral
Software Connectors
The Web as a Software Connector
BP
RESTful Process Engine API
Remote Process Call
POST /process/name HTTP/1.1
...after some time...
HTTP/1.1 200
Process Completed
Let's have a RESTful Conversation with a Process
POST /process/name?start HTTP/1.1
HTTP/1.1 201 Created
Location: /process/name/42
GET /process/name/42
HTTP/1.1 200
Link: </process/name/42/task>; rel="task"
Process Instance 42 is running
GET /process/name/42/task
HTTP/1.1 200
PUT /process/name/42/task
HTTP/1.1 200
GET /process/name/42
HTTP/1.1 200
Process Instance 42 is complete
Processes as Resources
- Bookmark a process instance
- Ask a process instance for links to its pending tasks
- Drive the execution of tasks with PUT/POST/DELETE
- Monitor processes using an RSS/ATOM feed
- Fetch links to active, completed, failed process instances
- Control which subset of tasks is actually exposed as resources
Resources as Processes
Publish resources from processes that drive their internal state transitions
- Activate process control flow on requests routed to resources managed by processes
- Produce responses from process data flow
- Control the lifecycle of resources from the process model
- Mint resource identifiers from process instances
- Map resource identifiers to process instances
RESTful Process Engine API
- Processes can be published as resources
- Only the visible part of processes should be published as resources
- Resource state transitions can be driven by process models
REST Architectural Elements
- User Agent
- Proxy
- Gateway
- Origin Server
- Gateway
- HTTP
- Cache
REST middleware is primarily designed to scale a single server, which may need to service a large number of clients
A Composite REST service provides an aggregated view over the state of multiple REST services
The behavior of /C is defined by
composing /R and /S
The composite resource /C only aggregates
the state of its components /R and /S
The composite resource /C augments or
caches the state of its components
Composing Representations with Hypermedia
The composite representation C refers to its component resources /R and /S via hyperlinks
A composite representation is interpreted by the client that follows its hyperlinks and aggregates the state of the referenced component resources
A composite representation may be retrieved from a composite service