Client Server Applications

Before PCs became common place applications lived on the same servers as the data and where delivered to the end-user using 'green-screen' technology. Things have changed and the following questions need to be answered before an application can be designed and deployed.

	Where do the client applications reside. Client application can be on the database server, or the end-user's PC or on an application server that sits between the PC and the server.
	Should the database be distributed or centralised. Although the database is global logical areas may be distributed onto national servers. It might be the case that the size of the database is such that a single server solution is not possible and the database must be distributed across multiple servers to achieve the performance that is required.
	What is the communication layer between the application and the server. Local clients can communicate either via shared memory or TCP/IP. Connecting via shared memory do not incur the added networking costs, but again the server might not be capable of supporting the application and the database.