Challenges
The convergence of SOA and SaaS is not without its challenges and risks.
In delegating to remote services over the public untrusted Internet, you often need to be concerned with security. This risk can be mitigated effectively with a combination of application and communications security. Application security typically includes username and password login to the remote service before use, while communications security may be implemented with SSL; for example, HTTPS.
Licensing is another challenge for SaaS. Many of today's SaaS services are offered free. However, for SaaS to grow to its full potential it must be funded, and some providers of services need to get revenue from the use of their services to offset the cost of ongoing hosting and development of new software services. Early forms of such licensing are emerging that involve signing up at web sites associated with the SaaS provider, providing billing information over the Web, receiving a key in response, and sending this key with requests for services. This approach enables the SaaS provider to accurately bill for their service usage. This model of usage moves SaaS toward a utility pay-as-you-go model.
Network and service reliability is yet another challenge with SaaS. When deciding to delegate geocoding over the Web, one has to consider the scenario of network or service outages that could compromise our local Mapping Service and break its clients. Some strategies to mitigate these risks may include redundant network connectivity, so if one channel fails, another will be available. Similarly, behind a service such as the Mapping Service, you may have the capability to delegate to several remote geocoding services. If one goes down, this failure is detected and the Mapping Service implementation automatically fails over to an alternate remote service. This ensures continuity of service to clients of the Mapping Service.
Conclusion
SOA has proven itself in architectures today as a tool to integrate, consolidate, and reuse services. Concurrently, SaaS has established itself as a successful method to deliver business services across the Web. Together, these driving forces may be leveraged as discussed in this article to deliver federated SOA over the Web, and powerful new business capabilities.
