Recently, I met an executive of a top bank who was trying to roll his head around the notion of software as a service and service oriented architecture. He intimated to me that these two terms are the only things he hears from software development vendors and the internal Information Technology team. I offered an explanation that went as follows.
Software as a service represents a shift in the way software is developed and used. In traditional software development, the software executable or program code is installed on the users computer. This requires a copy of the same software for each user creating challenges in updating, maintenance and licensing.
SaaS allows software to be installed and used over the Internet or Intranet. It allows a single copy of the same software to be used by different users from a single location through the network, which may be intranet or internet. Even when multiple copies are deployed, they provide redundancy rather than a copy for each user. Under SaaS, access to the software is strictly through external Application Programming Interfaces (API). To encourage loose coupling, the mode of communication is usually message passing. Because the software is used through an external interface and most often owned by a different party, this is sometimes referred to as consuming a service.
An architecture that is based on consumption of different capabilities of software programs by way of external interfaces is called a Service Oriented Architecture (SOA). With SOA, solutions can be built faster because we rely on existing SaaS functionality and add only what is missing. Incase of failure of one SaaS provider, it is possible to switch to other providers. Moreover, most SaaS vendors allow consumers to pay for only what they consume.
He appeared to understand and promised to get back to me, and will give feedback as soon as I hear from the manager.
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To begin with there has been considerable attention to web services in the last couple of years since early 2000. For starters web service are no more that applications that are designed to be used across the web. Web services provide a program-to-program programming model where one service invokes another using web standards including the well known HTTP and XML. Here I outline the main benefits, some technical others business.
- Interoperability – when faced with a challenge varying systems architectures, legacy systems, a cocktail of programming languages that make up systems that make up systems which need to be integrated then web services come in handy. Perhaps the most important benefit of web services they provide a non proprietary means of interactions. Web services only need to speak the same message protocol for them to inter-operate. So far a common set of standards-based communications method that include HTTP, WSDL, SOAP have been developed. These make it possible for web services to be platform-independent.
- Usability – web services are designed to be used over the web, that is just in the same way a page is fetched, one can fetch web services capability over the web. The capability of a web services varies from simple information lookup to complex algorithmic computations. Therefore when a service is used to expose a business logic, then it can easily used.
- Re-usability – Web Services are designed to be combined to deliver more added value services. Web services serve as building blocks and this makes it easy to reuse Web Service components as appropriate in other services. Also legacy applications can be wrapped into web services for use by others
- Deploy ability – Web Services are deployed over standard Internet technologies. For instance using Apache, Axis2 to provide HTTP, WSDL driven services. This makes it simple to deploy
- Agility – this looks at ability to change. When a an enterprise IT infrastructure is streamlined into services, new functionality to address new business demands is a matter of assembling existing services. Of course a few more services may need to build, but overall it is easier that re-building a new system from scratch.
- Quality – Related to reuse, because web service development approaches allows services to be built by assembling existing existing services, it logical to expect that such services are already tested with known performance characteristics. Therefore new systems will be less buggy.
- Cost – The cost of developing new systems reduces significantly since such systems are assembled from ready made web services. Such cost reductions translate into profits on may be passed on the customers. The customers stand to win from cost cuts and efficiency brought in by web service
Overall, an enterprise that streamlines its operations into web services stands to benefit in many aspects.
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