Quickly eclipsing screen-scraping tools are those that create a graphical look for the mainframe application within a browser. Mass. While this approach lets you extend the application's reach to new users, it limits the extension of the application's use. Those changes may be necessary if the application is to serve new users in new ways. A more sophisticated approach to bringing legacy applications to the web is to deploy an application server on a middle tier, between the web server or the client and the host. While more time-consuming than the other approaches, the desire to extend the use of legacy applications and data is a key reason why many firms are moving toward this emerging technology, says Phil Costa, senior industry analyst for Giga.
Application servers make it easier for developers to build distributed systems.
An application server behaves like a middleman, connecting a variety of applications and data sources on the back end with a variety of clients on the front end, and handling such details as load balancing and transfers to transaction processing monitors. Importantly, application servers follow a component-based development approach, so different technologies and different platforms can work together. Costa believes application servers offer several major advantages. For example, each of your bank accounts and loans are probably managed independently in separate legacy applications. This is not a problem for the experienced customer service rep who logs into the different applications to get the information you need when you call.