Sean Sutton
Sep 3, 2018 · 4 min read

Client/Server Model


What is it ?

Client server model is a distributed application structure that seperates tasks or workloads between servers and clients. Often clients and servers comunicate through computer networks, independent from each other on seperate hardware but both must remain in the same system.

Esscientally a server host will run one or more programs and share its resources with the clients requesting them. A client does not share of its resources but instead makes request to a server for content ot service function. Clients are the party that initiates comunication with servers who await incoming request. Some easily reconized examples of this model are Email and the internet.


History of server based computing

One this first examples of a client side model is “remote job entry ” which was introduced on os/360 1963, where the request was to run a job and the response was the output. While coming up with the client server model in the 1960s and 70s staff at the Standford research Institute coined terms such as server-host and client host and user-host while designing Arpanet … these terms found their home at in the mid 1970s

These terms also lent themselves to researchers in the budding days of designing a computer network programming language called D.E.L “decode-encode language”

Whos primary function resemlded a primitve get and post system. It would take users input encode the input into network packets and return a status report to the user

While another D.E.L enabled machine would receive those packets decode them and return requested data to the user, a separate D.E.L based program would them interpret the formatted data into user friendly text and thus began the era of client server transactions. Del was then used in 1969 but the department of defense in their implementation of Arpnet which was the predecessor to the internet .

From the 1980s to the 1990s micro computers and home computers dramatically started dropping in price at the same time increasing in power. This drop in price and increase in power set the stage for many companies and labs to start transitioning away from centralized servers like mainframes and mini computers . this gave each individual machine more power over localized resources but dramatically complicated information management.

In the early 2000s web applications began to rival application software , which meant for the first time people were able to utilize software that was as powerful and complicated as their locally installed programs completely remote, this in turn opened the market for cheaper,more efficient mass storage which drove the rise of cloud computing of today.

Now a days Browsers comunicate with web servers using http or hyper text tranfser protocol

When ever u click a link on a button on a application , hit submit or use a web site or application to search for something that web application sends a HTTP request to a server.

Request usually include

  • A URL identifying the target server and resource (e.g. an HTML file, a particular data point on the server, or a tool to run).
  • A method that defines the required action (for example, to get a file or to save or update some data). The methods I’ve used so far are
  • GET: Get a specific resource (getting users information).
  • POST: Create a new resource (such a new user or new product)

On the server side of things servers wait to receive request so they can process them and reply by sending a HTTP response message . HTTP response messages in a status code some common ones are 200 for a successful transaction 404 which mean whatever the client was requesting was not found and 500 meaning there was a server error. The body of a get request would normally contain the resource or data that the client requested while the body of a post might have a message stating that the data sent has been received by the server.

In conclusion Client server models are the internet. Without the ability to remotely process large amounts of data we would be restricted to only have access to locally housed databases and programs. The amount of educational and entertainment content the internet affords wouldn’t exist.

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