SOA, Web Services, Ajax and Mash-up – an overview

Nowadays you can hear buzz words like Service Oriented Architecture, Web Services, Ajax and Mash-up. But for the average business oriented person they can be hard to understand. So what do they mean and what have they got to do with each other?

Let’s try to shed some light on this.

Service Oriented Architecture (SOA) is a concept of making functionality, complex or simple, that is handled by a specific system or server, available to the outside world. This outside world can be inside your own company or exposed over the internet. The service can be called upon as and when it is needed by any other component as part of various business processes.

Web Services is a bit of a misleading name. It implies it is a service exposed over the Web but that doesn’t need to be the case. A Web Service is the technology in which a service can be approached. This service can expose itself over any network connection, including the internet. Hence the misleading name.

Active Javascript And Xml (Ajax) is not really something new. The concept of Ajax has been around for years but of late, more and more development environments have supplied the software industry with tools to make it easier to build browser based applications that interact and feel like more traditional (windows-) based applications. So now you can see more and more application developments creating rich user interfaces for their web applications.

A mash-up can be compared to a portal where various functionalities from different sources and applications are placed on one screen and these various (usually small) functionalities can interact. A common example is the screen that shows the latest news, has an overview of the outstanding tasks and shows, once a task has been selected, the location for that task in a map.

So how does it all link together?

This question is probably best answered by using an example.

Suppose your company has a server that holds all the accounts receivable information. As part of an SOA, a service is created that can expose outstanding balances based on a customer code. This piece of software on the accounts receivable server uses a web service to expose itself.

On the actual webpage that you see, an area of the screen can be used to query these outstanding balances using Ajax. The customer code comes from another area of your screen where all your tasks for today are. Once a task has been selected (clicked on) it takes the customer code from that task (in this case a task could be a phone call) and queries the web service for all outstanding balances. The result is shown next to your calendar. And it does this without contacting the server for an entire new page. It only gets the little bit of info that is needed to display the balances. So now, before you make the call, you can see if there is anything in particular going on with this customer that you may be able to mention during your phone call.

So now the browser contains a mash-up page and the accounts receivable server fits into a Service Oriented Architecture.

Of course this is but a simple presentation of the reality and in real-life there are many issues to consider (security, availability and protocols) but it does give an overview of how it is tied together.