1. Wilson 1 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Service Casting: A Proposal for Advertising Web Services Brian Wilson Jet Propulsion Laboratory Advertise Web Services via Atom feeds, enabling simple aggregation, discovery, & machine invocation.

2. Wilson 2 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Reduce advertising services to publishing an scast (Atom) feed n Feed readers already aggregate & filter feeds n Search also available n Decentralized repository with auto-aggregation n Service providers control publishing of advertisements n Scast discoverable in the cloud n Publish scast to Federation list by creating wiki link n Script auto-aggregates to list of scasts (OPML file) n Scast contains machine-readable metadata to categorize services and enable auto-invocation n Links to interface, service endpoint, human documentation n So simple it will be adopted (unlike previous attempts). n Make free tools available n Evangelize Motivation & Goals

3. Wilson 3 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Advertise bundle of Web Services via Atom Feed n Service Casts (scast) from many providers n With links pointing to callable interface (WSDL) & docs. n Service provider pushes new ads when services change, or periodically n Simple Aggregation & Display n All feed readers aggregate multiple feeds & import OPML n Publish bundled ads on Federation web site as OPML file n Display feeds in HTML or custom feed reader n Discovery n Can search for feeds in Google FeedReader n Provide opensearch interface that returns scasts n Machine Readable => Auto Service Invocation n SOAP/REST service interfaces described by WSDL n Or REST interfaces described by WADL n Or known interfaces for OGC WMS/WCS/WFS Service Casting Quick Summary

4. Wilson 4 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Multiple Typed Links possible in each Entry n type=application/wsdl+xml href= /> n Links to interface, service endpoint, & human documentation n Can embed tags from arbitrary namespaces n Define scast namespace, and register it n = SOAP, REST, OGC.WMS, HUMAN n Specific services can embed more XML metadata (sciflo) n Embed arbitrary content in typed tag n n Use for more documentation, or more XML metadata n Use tag to characterize services n Use taxonomy of services, or just text keywords n Opensearch and GoogleData standards extend Atom n Atom got timestamps right (unlike RSS) n ISO YYYY-MM-DDTHH:MM:SS Why Atom feed instead of RSS?

5. Wilson 5 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Service Types n SOAP (WSDL) n REST (WADL), n OGC.WXS: WMS, WCS, WFS, etc. n HUMAN (for human-oriented GUIs) n What else? n Service Type tells machine how to interpret links n For SOAP, parse WSDL interface bundle and call service n For REST, parse WADL interface and call service n For OGC, do GetCapabilities call n For human GUI, use serviceEndpoint link to load GUI n How do we type the variety of REST semantics? n Use REST.XXX for service type n Use to further specify semantics of call n What services are well known besides OGC.WXS? Service Types

6. Wilson 6 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Service Cast Namespace n scast = http://sciflo.jpl.nasa.gov/ServiceCast/2008v1http://sciflo.jpl.nasa.gov/ServiceCast/2008v1 n Links have typed purpose (rel attribute) n Rel = scast:interfaceDescription n URL pointing to WSDL, WADL, or WXS GetCapabilities call n Also the default link for each feed entry n For human-oriented GUIs, this link probably the same as serviceEndpoint. n Rel = scast:serviceEndpoint n URL pointing to where services can be called n For SOAP, also contained in WSDL file n Rel = scast:serviceDocumentation n URL pointing to human-readable documentation n Also the alternate link for each feed entry n Rel = what else? Typed Links

7. Wilson 7 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle Feed Reader View Firefoxs Feed Reader: For SOAP services, default links point to WSDL interface.

8. Wilson 8 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Simple service to create an scast n http://tinyurl.com/createSCast n Select REST or SOAP version of service n Hit execute n Result is scast (clink download link at bottom of results page n If your browser auto-displays Atom feeds, youll see it. n Use page source to download XML text n Aggregating scasts n Send me the URL pointing to your scast feed (Brian.Wilson@jpl.nasa.gov)Brian.Wilson@jpl.nasa.gov n I will aggregate them onto a ESIP Federation page, and an OPML file that can be imported into feed readers n If you have suggestions or questions about some fields, email me. Create An SCast

9. Wilson 9 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle Scast feed format

10. Wilson 10 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle Scast feed entry

11. Wilson 11 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle Scast feed entry (2) (rest of entry)

12. Wilson 12 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle HTML View in Browser Convert SCast to HTML view using XQuery or XSLT stylesheet

13. Wilson 13 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle Readers Import List of SCasts Feed Readers import OPML feed lists (OPML = outlining standard)

14. Wilson 14 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle SCast Distributed Architecture ESIP Federation SCast List SCast Feeds In the Cloud Wiki, OPML Human Clients Machine Clients Load OPML into Feed Reader, Or peruse Wiki Catalog Search GUI OpenSearch GData Federation 2 nd Feed Aggregation 3 rd Feed Aggregation Auto - Invoke the Service! NASA EPA NOAA Etc. Service Providers

15. Wilson 15 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n You can never be too simple, or have too many interfaces. n SCast feed links on ESIP Federation wiki page n Any service provider can add their ad feed n Scasts are auto-aggregated from wiki into OPML file n OPML catalog can be XSL-transformed into HTML viewable catalog n Opensearch / GoogleData interface n Everything is search, all results are feeds. n Search/filter scasts using REST call n Human GUI for feed search n Many feed readers n What else? Interface, Interface, Interface

16. Wilson 16 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Everything is search, all results are feeds! n Discover Service Bundles (scast entries) n /scast/-/services?q=parameter+subsetting &startIndex=1&count=200&format=atom n Returns scast entries satisfying query keywords n Discover Services by Provider n /scast/-/services/providerId?q=space+reprojection &startIndex=1&count=200&format=atom n Returns scast entries only from that provider n OpenSearch (GData) Features n GoogleData standard uses and extends OpenSearch n Search aggregators auto-handle Atom feed, traverse result sets n Google already crawls Atom feeds, making them searchable Open Search Interface

17. Wilson 17 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Describe owner of scast n tag, or link n n Could also reuse Dublin Core tags, n Categories (contents of tag) n Just text keywords? n Develop services taxonomy? n Specify availability and maturity of the feed n Experimental, or operational 24x7 n Add tag to point to other scasts n Create a web ring of scasts n Could point to related or recommended alternative scasts n n Who is allowed to use the service? Permissions? n Response to Steve Oldings Comments

18. Wilson 18 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Solicit Feedback n Missing service types? n Categorizing services – taxonomy? n Adoption n Twist arms RIGHT NOW to author scasts n Evangelize within Federation n Author feeds for people, and send them the draft n Make free tools available n HTML views of scast and OMPL using stylesheets n Custom feed reader / filter n Promulgate as wider standard n Scasts for everyone, simpler than UDDI n Generate scast of all services registered in ECHO (??, info. for all three links might not be present) Issues / Future

19. Wilson 19 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Reduce advertising services to publishing an scast (Atom) feed n Feed readers already aggregate & filter feeds n Search also available n Decentralized repository with auto-aggregation n Service providers control publishing of advertisements n Scast discoverable in the cloud n Publish scast to Federation list by creating wiki link n Script auto-aggregates to list of scasts (OPML file) n Scast contains machine-readable metadata to categorize services and enable auto-invocation n Links to interface, service endpoint, human documentation n So simple it will be adopted (unlike previous attempts). n Make free tools available n Evangelize Summary

20. Wilson 20 ESDSWG Meeting, Philadelphia, PA, Oct. 21-23, 2008 Carbon Cycle n Lets author some scasts!!! n Download example files: n http://sciflo.jpl.nasa.gov/sciflo/web/feed.atom.xml n http://sciflo.jpl.nasa.gov/sciflo/web/EsipFederationServices.opml.xml n Author a ServiceCast n Start with feed.atom.xml n What is the service type? Need a new type? n Lookup URLs to your interface (WSDL, WADL, GetCapabilities), service endpoint, and docs. for humans n Provide feedback and suggestions n Explore capabilities of your favorite Feed Reader n How does it format the scast? n Can you filter on text keywords? n Publish your ServiceCast on the Federation wiki Required Lab