Computer network programming: Difference between revisions

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{{Short description|Writing computer programs with networking capability}}

In [[computing]], '''network programming''', essentially identical to ''[[Internet socket|socket]] programming'' or ''[[client-server]] programming'', involves writing [[computer programs]] that communicate with other programs across a [[computer network]]. The program or process initiating the communication is called a [[client (computing)|client]] process, and the program waiting for the communication to be initiated is the [[Server (computing)|server]] process. The client and server processes together form a [[distributed system]]. The communication between the client and server process may either be [[connection-oriented]] (such as an established [[Transmission Control Protocol|TCP]] [[virtual circuit]] or [[Session (computer science)|session]]), or [[connectionless]] (based on [[User Datagram Protocol|UDP]] datagrams).

{{one source|date=June 2013}}

{{For|similar terms referring to the hardware technologies committed to computer network programming |Computer network}}

A program that can act both as a client and a server is based on [[peer-to-peer]] communication.

'''Computer network programming''' involves writing [[computer programs]] that enable [[process (computing)|processes]] to communicate with each other across a [[computer network]].<ref>{{cite book| url=http://people.scs.carleton.ca/~lanthier/teaching/COMP1406/Notes/COMP1406_Ch12_NetworkProgramming.pdf | archive-url=https://web.archive.org/web/20200305163115/http://people.scs.carleton.ca/~lanthier/teaching/COMP1406/Notes/COMP1406_Ch12_NetworkProgramming.pdf | url-status=dead | archive-date=2020-03-05 | chapter=Chapter 12 - Network Programming | date=2017 | quote=Network Programming involves writing programs that communicate with other programs across a computer network. | title=COMP1406 }}</ref>

Sockets are usually implemented by an [[Application programming interface|API]] library such as [[Berkeley sockets]], first introduced in 1983. Most implementations are based on [[Berkeley sockets]], for example [[Winsock]] introduced 1991. Other socket API implementations exist, such as the [[Streams (networking API)|STREAMS]]-based [[Transport Layer Interface]] (TLI).

== Connection-oriented and connectionless communications ==

These are examples of functions or methods typically provided by the API library:

* <code>socket()</code> creates a new socket of a certain socket type, identified by an integer number, and allocates system resources to it.

* <code>bind()</code> is typically used on the server side, and associates a socket with a socket address structure, i.e. a specified local port number and IP address.

* <code>listen()</code> is used on the server side, and causes a bound TCP socket to enter listening state.

* <code>connect()</code> is used on the client side, and assigns a free local port number to a socket. In case of a TCP socket, it causes an attempt to establish a new TCP connection.

* <code>accept()</code> is used on the server side. It accepts a received incoming attempt to create a new TCP connection from the remote client, and creates a new socket associated with the socket address pair of this connection.

* <code>send()</code> and <code>recv()</code>, or <code>write()</code> and <code>read()</code>, or <code>recvfrom()</code> and <code>sendto()</code>, are used for sending and receiving data to/from a remote socket.

* <code>close()</code> causes the system to release resources allocated to a socket. In case of TCP, the connection is terminated.

Very generally, most of communications can be divided into [[Connection-oriented_communication|connection-oriented]], and [[Connectionless_communication|connectionless]]. Whether a communication is connection-oriented or connectionless, is defined by the [[Communications_protocol|communication protocol]], and not by {{nowr|[[application programming interface]] (API)}}. Examples of the connection-oriented protocols include {{nowr|[[Transmission Control Protocol]] (TCP)}} and {{nowr|[[Sequenced Packet Exchange]] (SPX)}}, and examples of connectionless protocols include {{nowr|[[User Datagram Protocol]] (UDP)}}, "raw IP", and {{nowr|[[Internetwork Packet Exchange]] (IPX)}}.

== See also ==

* [[Inter-process communication]] (IPC)

== Clients and servers ==

==External links==

{{main|client–server model}}

* [http://beej.us/guide/bgnet/ Beej's guide to network programming]

* http://www.kohala.com/start/preface.unpv12e.html

For connection-oriented communications, communication parties usually have different roles. One party is usually waiting for incoming connections; this party is usually referred to as "[[Server_(computing)|server]]". Another party is the one which initiates connection; this party is usually referred to as "[[Client_(computing)|client]]".

* http://java.sun.com/docs/books/tutorial/networking/overview/networking.html

For connectionless communications, one party ("server") is usually waiting for an incoming packet, and another party ("client") is usually understood as the one which sends an unsolicited [[Network_packet|packet]] to "server".

== Popular protocols and APIs ==

Network programming traditionally covers different layers of [[OSI_model|OSI/ISO model]] (most of application-level programming belongs to L4 and up). The table below contains some examples of popular protocols belonging to different OSI/ISO layers, and popular APIs for them.

{| class="wikitable"

! OSI/ISO Layer

! Protocol

! API

|-

| L3 (network)

| [[Internet Protocol|IP]]

| [[Raw socket]]

|-

| L4 (transport)

| [[Transmission Control Protocol|TCP]], [[User Datagram Protocol|UDP]], [[Stream Control Transmission Protocol |SCTP]]

| [[Berkeley Sockets]]

|-

| L5 (session)

| [[Transport Layer Security|TLS]]

| [[OpenSSL]]

|-

| L7 (application)

| [[HTTP]]

| Various

|}

== See also ==

* [[Software-defined networking]]

*[[Infrastructure as code]]

* [[Site reliability engineering]]

* [[DevOps]]

== References ==

{{compu-prog-stub}}

* W. Richard Stevens: '''[[UNIX Network Programming]]''', Volume 1, Second Edition: Networking APIs: Sockets and XTI, Prentice Hall, 1998, {{ISBN|0-13-490012-X}}

{{reflist}}

[[ru:Программирование сетевых задач]]

[[Category:Computer networks engineering]]

[[[[Link title]][[[[Link title]][[''Link title''''''Italic text'''''{| class="wikitable"

[[Category:Computer programming]]

|Bold text

* [[Category:Inter-process communication]] (IPC)

|}''''']]]]]]