's Blog

One requirement for GEOSS and OWS-5 is to seamlessly interface with several workflow engines (BPEL, OpenWFEru and SensorML). These workflows will have to be fully accessible as resources over the web and discoverable.

A lot of work has been done in that area by the Workflow Management Coalition Group (WfMC). Wf-XML 2.0 is the current XML-based protocol for run-time integration of process engines. Several issues are hindering the effort. SOAP 1.2 is still not supported by SOAP4R and the Ruby code generated from the WSDL file is questionable. And by the way, WSDL 2.0 has just been approved by the W3C.

Wf-XML relies on the OASIS Asynchronous Protocol (ASAP) which is still in draft form while the W3C is proposing WS-Addressing. If we are there, then might as well look at the WS-Notification group of specifications… grrrr! Does not look easy…

Plan B is to take a step back and look at a RESTful approach and consider workflows as web resources. It ought to be straighforward to create an entry for a workflow, add versionable definitions for that workflow and create instances to run. The proposed approach is to create a RESTful access to those collections and publish the services using the new Atom Publication Protocol.

These workflows ought to be searchable via an OpenSearch web service that would output atom feeds.

Notifications could happen using Twitter or any simlar Publish/Subscribe mechanism.

A simpler SOAP service could be implemented later on top of that architecture.

Here is the plan for a demo:

A Web Feature Server (WFS) in its basic incantation is really a store of geospatial collections that can be accessed using RESTful services.

Building Web Services the REST way has been a very hot topic in the Rails Community.

Rails 1.2 can quickly allow you to build such services and return xml or html on-demand. JSON or [Geo]-rss/atom could be returned as easily in a similar manner.

The idea here is to return a GeoAtom Feed that could follow a similar structure as GData with a namespace specific to that WFS and an additional extension for the geospatial component.

Discovering the meta-data should be feasible using a meta-data feed and probing a specific url.

This would give us many services to access the various collections and the meta-data. The whole package could be described using a service document as proposed in the Atom Publishing Protocol (APP) that would describe all the available services. This document itself would be available at a specific url.

Searching the WFS would be done via OpenSearch-Geo which is another REST service returning atom or KML feeds.

The goal is to implement this for the upcoming ESTO/AIST Fire Management demo this summer and support the GEOSS Pilot effort this fall. This is also in line with our participation into the OWS-5 Agile Geography testbed.

A Few Links:

Get to know APP

Dreaming of An Atom Store

Great article From Sandra Upson in Spectrum Magazine.

“Making such work as simple as a Web search is the central objective of the Global Earth Observation System of Systems (GEOSS), an endeavor taking its first baby steps this summer….Scientists inch toward a standardized, universal system…”

It is all about interoperability and working together :)

Great article in Goddard Tech Trends this month. “Using the Internet to cross-link and Task Earth-Observing Sensors”. This is a wonderful follow-up to our interoperability effort with OWS-5 and our GEOSS Pilot Program.

Tomorrow is the Kick-off for the Open Geospatial Consortium Interoperability initiative testbed activity Phase 5 (OWS-5) in Reston Virginia.

We will be presenting [G]EO-Web: our multi-sensor web-based architecture. Workflows for SensorWeb processing will be heavily debated.

Our Approach:

• BPMN 1.0 for the presentation layer
• XPDL 2.0 for model persistence
• Workflow Chaining Service API for runtime control (loosely based on an harmonized version of SPS/WPS and Transactions)
• Identity 20 with OpenID and SSL-PKI

This will be the first official presentation of GeoBPMS: Our GeoSpatial Business Process Management System to be integrated with our GeoBliki SensorWeb Enabled Data Nodes.

All Open Source and Standards-based: it will feature the OpenWFEru workflow engine, Rools, a ruby rules engine, Community MapBuilder, XForms and Matelot, an upcoming FLEX-based workflow navigator.

This will be interesting and will get us ready for GEOSS International Pilot Program later this year in South Africa… We will need some help!

Please contact me if you are interested.