Define the Example Client-server Implementations

Once you accept the client-server mindset, the process of architecting and developing applications becomes rather easy. Clearly, there is a wall of acceptance between requesting (client) and responding (server) components. This new architecture for applications can be easily achieved by creating application functions and procedures as self- contained components. Each component can only interact with others through this well- defined interface. Self- contained application components are a requirement for client server programming. The client- server application developer must make important architectural choices from the beginning. Choosing the interface between components is a fundamental decision affecting how the two application partners, client and server, interact. I will provide examples using both a procedural interface and a message- based interface for this interaction. In addition, my client- server application protocols will model the interface choices by being flexible and predefined, respectively. Each method, actually any client server interaction, has five main characteristics:

• The interface between Request/response components
• The formulation of requests from the client side
• The transmission of request between components
• Acceptance and unpacking of request from the client
• The execution of request at the server side

For client and server components to interact, a series of steps must be taken as documented above. First, an interface needs to be defined between requesting and responding components. This interface will vary widely based on the communications technique being implemented. Requests then need to be broken down at the client, communicated to the server, accepted, and executed.

The formulation and acceptance or requests will vary based on implementation. The core transmission and execution requirements will remain relatively similar no matter what interface is chosen between client and server components. Please refer to the following sections for in-depth examples. It is also important to note that for client-server communications to take place in a secure environment, some form of authentication of client must be performed. This authentication will be performed when initial contact is made between the client and server. This contact (or location of services) will be initiated by the client application programmer and authenticated by the server.