Standard Client-Server protocold, - Coggle Diagram
Standard Client-Server protocold
the service provider is an application program, called the server process
make a connection through the Internet and ask for service.
some server processes that can provide a specific type of service, but there are many clients that request service from any of these server processes.
the server should be a powerful computer
WORLD WIDE WEB AND HTTP
World Wide Web
Uniform Resource Locator (URL)
A web page, as a file, needs to have a unique identifier to distinguish it from other web pages
To define a web page, we need four identifiers: protocol, host, port, and path.
Architecture of WWW
a client using a browser can access a service using a server.
Each site holds one or more web pages
can contain some links to other web pages in the same or other sites
a web page can be simple or composite
HyperText Transfer Protocol
used to define how the client-server programs can be written to retrieve web pages from the Web.
An HTTP client sends a request; an HTTP server returns a response
Ports used on servers are persistent in the sense that they last for a long time
Ports used on clients are ephemeral (“lasting a short time,”)
HTTP uses the services of TCP
After the transaction, the connection should be terminated.
File Transfer Protocol (FTP) is the standard protocol provided by TCP/IP for copying a file from one host to another.
Although we can transfer files using HTTP, FTP is a better
choice to transfer large files or to transfer files using different formats.
The client has three components: the user interface, the
client control process, and the client data transfer process.
The server has two components: the server control process
and the server data transfer process.
The control connection is made between the control
processes and the data connection is made between the data transfer processes
The control connection uses very simple rules of
The data connection, on the other hand, needs more complex rules due to the variety of data types transferred.
The control connection is opened by client and remains
connected during the entire interactive FTP session.
The data connection is opened and then closed by server for each file transfer activity.
FTP uses two well-known TCP ports: port 21 is used for the
control connection, and port 20 is used for the data connection.
Allows users to exchange messages
e-mail is considered a one-way transaction
the idea of client/server programming should be implemented in another way: using some intermediate computers (servers).
The users run only client programs when they want, and the intermediate servers apply the client/server paradigm
E-mail exchanges can be secured using two application layer securities designed in particular for e-mail systems.
Two of these protocols, Pretty Good Privacy (PGP) and
Secure/Multipurpose Internet Mail Extensions (S/MIME).