1.
RESTful Web Processing Service Theodor Foerster, Andre Bruehl, Bastian Schaeffer AGILE 2011, Utrecht, the Netherlands

2.
Why RESTful WPS? <ul><li>Representational State Transfer (Fielding, 2000) </li></ul><ul><ul><li>RESTful Web Services are available </li></ul></ul><ul><ul><li>For mapping & data </li></ul></ul><ul><ul><li>GeoWeb & Mashups </li></ul></ul><ul><ul><li>Producers = Consumers </li></ul></ul><ul><li>Processing missing, but essential </li></ul><ul><ul><li>Seamless integration </li></ul></ul><ul><ul><li>OGC WPS compatibility </li></ul></ul>

3.
Web-based Geoprocessing <ul><li>Data  Information </li></ul>GetCapabilities Execute WPS Process 1 Process 2 Process n DescribeProcess

4.
REST – architectural style <ul><li>“ ... a hybrid style derived from several of the network-based architectural styles [...] and combined with additional constraints that define a uniform connector interface.” (Fielding, 2000) </li></ul><ul><li>REST properties </li></ul><ul><ul><li>Addressability, statelessness, connectedness, uniform interface </li></ul></ul><ul><li>Resources accessible through URLs </li></ul><ul><li>HTTP Verbs </li></ul><ul><ul><li>GET, POST, PUT, DELETE,… </li></ul></ul><ul><li>Hypermedia approach </li></ul><ul><li>Representations & content negotiation </li></ul>

5.
REST for Geo <ul><li>Services available </li></ul><ul><ul><li>Google, Yahoo, GeoCommons, etc. </li></ul></ul><ul><li>Documents & specifications too </li></ul>

6.
Design approach <ul><li>Identify resources </li></ul><ul><ul><li>What are the relevant resources? </li></ul></ul><ul><li>Link resources </li></ul><ul><ul><li>How does the client navigate between the resources? </li></ul></ul><ul><li>Interaction with HTTP verbs </li></ul><ul><ul><li>How to build the functionality </li></ul></ul><ul><li>Multiple representations for the resources </li></ul><ul><ul><li>Which are the relevant representations? </li></ul></ul>

7.
Resources <ul><li>Links & navigation </li></ul><ul><li>Jobs & processes </li></ul>

8.
HTTP verbs - Examples <ul><li>Perform process </li></ul><ul><ul><li>GET: processes/[process_ID]?[parameters] </li></ul></ul><ul><li>Jobs </li></ul><ul><ul><li>POST: processes/[process_ID]/jobs </li></ul></ul><ul><ul><li>GET: processes/[process_ID]/jobs </li></ul></ul><ul><li>Job </li></ul><ul><ul><li>GET: processes/[process_ID]/jobs/[job_ID] </li></ul></ul><ul><ul><li>DELETE: processes/[process_ID]/jobs/[job_ID] </li></ul></ul>

9.
Representations <ul><li>ATOM, KML, GML, OGC WPS, JSON </li></ul><ul><li>Example – processes/buffer </li></ul>

10.
WPS Compatibility <ul><li>Processes modelled as resources </li></ul><ul><li>OGC WPS return formats possible through content negotiation </li></ul><ul><li>OGC WPS functionality fully reflected </li></ul><ul><ul><li>Process by reference </li></ul></ul><ul><ul><li>Synchronous & asynchronous processing </li></ul></ul>

11.
Implementation

12.
Client <ul><li>JavaScript & RESTful APIs </li></ul>

13.
Humanitarian relief workflow <ul><li>Evaluating campsites for medical access </li></ul><ul><ul><li>Inspired by OGC testbed </li></ul></ul><ul><li>GeoCommons </li></ul><ul><ul><li>Medical facilities </li></ul></ul><ul><ul><li>Campsites </li></ul></ul><ul><li>Interactive & client-based chaining </li></ul><ul><ul><li>Buffer, intersection & symDifference </li></ul></ul>

14.
Qualitative evaluation <ul><li>Addressability </li></ul><ul><ul><li>Each process & job is a resource and addressed via URL </li></ul></ul><ul><li>Statelessness </li></ul><ul><ul><li>Required information available at runtime </li></ul></ul><ul><li>Connectedness </li></ul><ul><ul><li>Resources are connected </li></ul></ul><ul><li>Uniform interface </li></ul><ul><ul><li>HTTP </li></ul></ul>

15.
Discussion & Outlook <ul><li>Difference to ESRI GeoServices </li></ul><ul><li>Towards modular specifications at OGC </li></ul><ul><li>Incorporating WPS-T </li></ul><ul><li>Link to open linked data to be investigated </li></ul>

16.
Conclusion <ul><li>REST is a hot topic </li></ul><ul><ul><li>GeoWeb & APIs </li></ul></ul><ul><li>Process as a resource </li></ul><ul><li>Seamless integration through REST </li></ul><ul><li>OGC compatibility </li></ul><ul><li>Humanitarian relief use case </li></ul>

17.
Thanks for your attention! <ul><li>swsl.uni-muenster.de </li></ul><ul><li>Theodor Foerster </li></ul><ul><li>[email_address] </li></ul>