Over the years movement of Integration platforms towards more reusability, industry standards approach to interoperability and better performance have resulted in SOA based architecture as a panacea for integration challenges.Some of these recommendations have resulted also in implementations , building application composed of webservices or orchestrating complete business processes using webservices.This has however resulted in multiple standards being adopted towards creating such platforms of reusability.This weblog intends to look at just some of these features that can have a major impact on any system landscape study that would need to be critically looked at by a Solution architect while designing Services using webservices over an EAI.
Webservices are basically a message based interfacing layers built over the existing applications/systems to basically achieve the following
Interoperability and integration capability:-
Webservices are a result of an evolution of consistent, standards based protocols linking together applications from a variety of legacy and monolithic architectures.Some of the lower level standards like WSDL and SOAP are widely adopted platforms for exposing functionality of business applications to EAI and middleware layers for seamless integration to other latest platforms.But the question is do we have the same kind of agreement on issues like security , reliability where the emerging standards are not yet agreed upon as the basis of collaboration between applications?
One answer to this question could be the Web Services Interoperability Organization(WS-I) whose WS-I Basic Profile 1.1 is considered a best practice towards creating webservices for attaining maximum interoperability. This can be verified by testing the developed webservices for conformance through actual webclients which would consume these services.Some off the shelf toolkits can also be used to verify the conformance of these webservices to the standards.
QOS:- QOS is an area, which I feel needs some thought, b’cos typically unlike an EAI where the standard product offerings provided QOS thro’ say the infamous CertifiedMessaging/RV of say Tibco or the BE/EO/EOIO mechanisms of SAP Xi, we may not be clearly able to define the QOS standards for messages from webservices which would come into the new landscape.I have faced this dilemma during many integrations involving webservices and WSFL standard based process implementations like Siebel UAN on Tibco.
Eg: How would you manage a HTTP synchronous call, which would required ‘n’ process calls to different application systems before the data from the different systems can be picked up, transformed and the content filtered before being sent as a single response from within EAI layer.(XI’s S-A bridge is one mechanisam which can bridge this problem, but in a multi application scenario, it may not be the solution to the problem)
But recently, reliable messaging standards have arrived that are protocol-independent like WS-Reliability and WS-ReliableMessaging which provide guaranteed messaging capability but choosing the infrastructure required for implementing them would still need an evaluation .
Performance:- As in any standard web based interface measurement strategy, the catch here is on the throughput of the server and latency time involving the request-response.This is dependent on the Network bandwidth, Server-Client performance, Message size, transformation logic involved and Memory- CPU constraints.
I havent dealt with other issues which may need to be considered in any Webservices strategy like message security , manageability of the deployments,clustering capabilities(in relevance to QOS) but these we can deal with them probably in a future weblog…