JDBC essays

JDBC essays The term client/server came into existence during the early 1980s when networking personal computers became popular. The basic concept behind the model is that there is one machine that request a service and one machine that provides a service. The machine making the request is known as the client and the one providing the service is the server. Before the client/server model was introduced there were two main distributed system models being commonly used but both were showing their age in the modern computing The first of these was the mainframe architecture. This had a powerful central host computer that carried out all the processing. To use the system the user connected to the mainframe via a dummy terminal. However as the industry moved towards the use of Graphical User Interfaces this model started to falter as incorporating them was very difficult. The second type is the file sharing architecture. In this model the server sends the requested file to the terminal where it can be used. This means that it uses the terminals resources taking a lot of strain off the server. However it does have problems if the amount of data being transferred is high and it can also lead to problems with data consistency because two people can call the file at the same time both make different edits and then both save. The person who saves the file first will lose all there changes once the second person saves. The number of simultaneous users was also very limiting. Only 12 people could connect at one time before performance became a significant problem The client/server model differs from these models because it uses a database server instead of a file server. The old mainframes are often used as the server in this system. This allows a user to query the files without downloading the whole files thus cuts down the amount of traffic that goes across the network. The Database Management system also ensures that referential integrity is...