Putting a Face to SOA

There seems to be some things missing from much of the discussion on SOA. In a couple of books I've read SOA as touted as an all-encompassing approach to developing systems but issues on data modelling and user interface are almost completely ignored. These are pretty fundamental parts of or software. Early computer systems were nothing but user interface and database. Now there is so much in between such as business logic and middleware that this all needs to be regarded as the most important part of the architecture. So are there recommendations about how to do the data model and user interface in SOA?

Firstly, does SOA affect the logical data model compared with traditional architectures? My answer is that the method of obtaining the data model may be different but I'm not sure whether the resulting data model is any different from traditional methods. The focus has to be on the message format if the development is to be driven WSDL first. I will probably expand on this in later post but for now I will focus on the user interface for the rest of this post.

The book Service-Oriented Architecture: Concepts, Technology, and Design by Thomas Erl provides good description of SOA and web services but the issue of user interface is never broached. The reader is left to wonder whether the user interface is somehow built into the services or sits outside it. Another book Enterprise SOA: Service-Oriented Architecture Best Practices by Dirk Krafzig, Karl Banke and Dirk Slama explicitly states that the user interface sit outside the service. An article by some IBM authors provides both scenarios. They observe that " The Model-View-Controller (MVC) paradigm underlies most modern UI application frameworks. SOA operations provide the model layer, and UIs occupy the view layer". (Hepper et al)

The IBM article discusses Web Services for Remote Portlet (WSRP) to enable a portal to aggregate content from multiple sources. The intention of WSRP is so that "Content and application provider services can be discovered and plugged into standards-compliant applications without any extra programming effort". This described more succinctly in another article "A remote portlet is a portlet that's deployed in a different environment than the portal that actually uses it" (Ort). The approach assumes the software developer has a portal for the portlet deployment.

The IBM article also looks at the human workflow. If all human interactions can be managed by forms within a workflow product then programmatic user interfaces could presumably disappear. The human workflow is included in the BPEL process designed to orchestrate the SOA. This may be good for simple forms but this is not going to suit all purposes.

There seems to be a weight of industry acceptance behind Rich Internet Applications in general and AJAX in particular. This user interface for SOA uses makes good use of the XML used in web services messages uses asynchronous messaging and is sufficient rich to provide users all they need from a simple web browser. This approach seems to be supported by Zapthink, Tibco and Oracle.

A number of products seem to be appearing that target the SOA user interface space. BEA systems, Sun Microsystems, CapeClear Software, Tibco (see footnote) all plan to add Ajax tools to their SOA-centric products (Meehan). Other solutions will also become evident from vendors like Corizon that use approaches to SOA user interfaces that differ to the AJAX approach.

The combination of AJAX and WSRP seems well accepted by the industry. "These two technologies complement each other in terms of ease of sharing of aggregated content and better usability of such content" (Padmanabhuni et al). AJAX support will be included in WSRP version 3 (Dovey). These technologies have been included in both the IBM Websphere and BEA Weblogic portal products. AJAX allows the interfaces with sufficient richness to be developed for Web Service applications and WSRP allows interfaces to be deployed and aggregated into portals easily.

It looks like the choice to use SOA and the choice over interface technology will always remain fairly independent although not unconnected. This could be an advantage as it will mean that that good user interface technology can develop reasonably independently for the evolving web services standards. A portal seems a generally accepted starting point for an SOA user interface. AJAX and WSRP are popular technologies to take advantage of web services. The human workflow approach as way for users to interact with SOA is worth watching. This will be an effective way to build workflow applications that have simple form-based user interfaces.

Footnote
Comments received on this blog suggest that Tibco have already released Ajax tools for their SOA product offering.

References
Erl, Thomas, Service-Oriented Architecture: Concepts, Technology, and Design, 2005 Prentice Hall

Krafzig, Dirk, Banke, Karl and Slama, Dirk, Enterprise SOA: Service-Oriented Architecture Best Practices, Prentice Hall, 2004

Hepper, S, Liesche, S and Stockton, M, http://www.ibm.com/developerworks/library/ws-soa-progmodel5/index.html

Ort, Ed, What's New in SOA and Web Services? http://java.sun.com/developer/technicalArticles/WebServices/soa2/WhatsNewArticle.html

Meehan, Michael, Vendors look to Ajax to make SOA shine
http://searchwebservices.techtarget.com/originalContent/0,289142,sid26_gci1144429,00.html

Padmanabhuni, S, Kunti, K, Sahoo, L and Bharti, S, Coupling RDF/RSS, WSRP and AJAX for Dynamic Reusable Portlets: An Approach and a Use Case, http://doi.ieeecomputersociety.org/10.1109/SERVICES.2007.26

Dovey, Matthew, WSRP2 and JSR286,
http://www.nesc.ac.uk/talks/686/10-00_Dovey-WSRP2-JSR286.ppt

Seeley, Rich, Ajax tools from IBM and real-time Java for SOA from BEA,
http://searchwebservices.techtarget.com/originalContent/0,289142,sid26_gci1213063,00.html

Seeley, Rich, BEA bets its portal on WSRP, Ajax,
http://searchwebservices.techtarget.com/originalContent/0,289142,sid26_gci1198691,00.html

Davies, David, SOA at the user interface, http://www.looselycoupled.com/opinion/2006/davies-ui-dev0424.html

Tibco, Rich Portals: The Ideal User Interface for SOA,
http://www.tibco.com/resources/mk/rich_portals.pdf

Bloomberg, Jason, Corizon: Leveraging User Interface Services for Rapid Application Creation
http://www.zapthink.com/report.html?id=ZTZN-1216