The Client/Server Relationship

Teach Me

Nodes that use the network's resources are called clients (usually computers), and nodes that manages the sharing of resources are called servers. Servers are specialized computers with their own operating systems and network administration software (see the task Network Software and Network Administration for more details about server software).

Servers can be specialized for a variety of functions:

• File servers are data repositories with large hard drives. By storing files on the server rather than on the individual client computers, multiple clients have access to the same files. File servers are designed to handle multiple file requests at the same time.
  
  
• Database servers store data in a large database. Rather than requesting data in the form of files, clients can request data from the database. Database servers include powerful data search and query functions. Database servers are optimized to search through large amounts of data and return only the records required to answer the question.
  
  
• Application servers allow clients to run applications from the server, rather than installing the application on each client individually.

Many servers provide a combination of these functions.

	When you are connected to the Internet, your computer acts as a client, viewing the data stored on a external computer (the server). Servers used specifically to provide Internet services are known as Web servers.
	In a network with a terminal server, the client computers have very little independent functionality. Instead, the server provides functionality to each client on an as-needed basis. Terminal servers are usually used in situations where the clients have a single function such as data input (order taking, reservation entry, etc.)

Show Me

Client/Server interaction:

1. Client sends request to server
   a. Sends log-in user name and password
   
   
2. Server responds
   a. Server validates that the user name and password are correct
   
   
3. Client sends another request
   a. Can I access files on this drive?
   
   
4. Server responds
   a. Server checks permissions for the user. If permission is granted, files are displayed. If not, a message denying access is sent.