IGNOU BCA 5th sem Solved Assignment -Explain different types of client-server architectures. Explain the GET and POST methods of HTTP protocol?

Explain different types of client-server architectures. Explain the GET and POST methods of HTTP protocol? Why do you use these methods? Explain with the help of an example each.

Ans

Client/server architecture This approach introduced replacement of file server by database server. User queries could be answered directly by using a relational database management system. The client/server architecture significantly decreased network traffic by providing a query response rather than total file transfer. It allows multi-user updating through a GUI front end to a shared database. Remote Procedure Calls (RPCs) or standard query language (SQL) statements are typically used to communicate between the client and server.

The following are the examples of client/server architectures.

1) Two tier architectures In two tier client/server architectures, the user interface is placed at user's desktop environment and the database management system services are usually in a server that is a more powerful machine that provides services to the many clients. Information processing is split between the user system interface environment and the database management server environment. The database management server supports for stored procedures and triggers. Software vendors provide tools to simplify development of applications for the two tier client/server architecture.

2) Three tier architectures The three tier architecture is introduced to overcome the drawbacks of the two tier architecture. In the three tier architecture, a middleware is used between the user system interface client environment and the database management server environment. These middleware are implemented in a variety of ways such as transaction processing monitors, message servers or application servers. The middleware perform the function of queuing, application execution and database staging. In addition the middleware adds scheduling and prioritization for work in progress. The three tier client/server architecture is used to improve performance for large number of users and also improves flexibility when compared to the two tier approach. The drawback of three tier architectures is that the development environment is more difficult to use than the development of two tier applications.

i) Three tier with message server. In this architecture, messages are processed and prioritized asynchronously. Messages have headers that include priority information, address and identification number. The message server links to the relational DBMS and other data sources. Messaging systems are alternative for wireless infrastructures.

ii) Three tier with an application server This architecture allows the main body of an application to run on a shared host rather than in the user system interface client environment. The application server shares business logic, computations and a data retrieval engine. In this architecture applications are more scalable and installation costs are less on a single server than maintaining each on a desktop client.

Uses Client/server architectures are used in industry as well as in military. They provide a versatile architecture that allows insertion of new technology more readily than earlier software designs.

Client-server describes the relationship between two computer programs in which one program, the client program, makes a service request to another, the server program. Standard networked functions such as email exchange, web access and database access, are based on the client-server model.

For example, a web browser is a client program at the user computer that may access information at any web server in the world. To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you.

The client-server model has become one of the central ideas of network computing. Most business applications being written today use the client-server model. So do the Internet’s main application protocols, such as HTTP, SMTP, Telnet, DNS, etc. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the “monolithic” centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client-server model and become part of network computing.
for a variety of reasons to many different kinds of applications, the architecture remains fundamentally the same.
The most basic type of client-server architecture employs only two types of hosts: clients and servers. This type of architecture is sometimes referred to as two-tier. It allows devices to share files and resources. The two tier architecture means that the client acts as one tier and application in combination with server acts as another tier.
These days, clients are most often web browsers, although that has not always been the case. Servers typically include web servers, database servers and mail servers. Online gaming is usually client-server too
The interaction between client and server is often described using sequence diagrams. Sequence diagrams are standardized in the Unified Modeling Language.
When both the client- and server-software are running on the same computer, this is called a single seat setup.
Specific types of clients include web browsers, email clients, and online chat clients.
Specific types of servers include web servers, ftp servers, application servers, database servers, mail servers, file servers, print servers, and terminal servers. Most web services are also types of servers.

Each instance of the client software can send-data requests to one or more connected servers. In turn, the servers can accept these requests, process them, and return the requested information to.the client. Although this concept can be applied