Computer networking application protocols

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	To oppose or discuss a nomination, please go to CZ:Proposed for deletion and follow the instructions. For the monthly nomination lists, see Category:Articles for deletion. Computer networking application protocols travel over computer networking end-to-end protocols]] to provide services meaningful to application program]]s residing in the endpoints. The application protocols differ in the kind of information they transfer (e.g., self-contained messages, file transfer|computer file]]s, remote procedure call]]s, spoken language]], etc.). Note well that these are not directly accessible to a human user. To draw an analogy to postal mail, a person can drop an envelope into a mailbox, but has no access either to the mechanism between mailbox and post office, or post office to post office. Application protocols also differ in their expectations of the performance end-to-end service below them. The application protocol may provide security, expect certain security services from the end-to-end or computer networking internetwork protocols]] over which they run, or both. Classes of information transfer Message Messages are self-contained units of data, which may contain other types of data. Message handling protocols are analogous to postal protocols. Different protocols run among mail clients that provide a human interface; message transfer agents analogous to post offices, possibly at multiple levels of a hierarchy; and message stores, analogous to temporary mailboxes. The major IETF message transfer paradigms and protocols include: Mail client to mail server: Post Office Protocol version 3]] (POP3), in which the messages are transferred to the client, and Internet Mail Access Protocol]] (IMAP), in which copies of the messages go to the client but the master copies remain on the server, They use a client-server]] model Mail transfer agent to mail transfer agent: Simple Mail Transfer Protocol]] (SMTP) exchanges messages, on a peer-to-peer]] model, among mail transfer agent]]s that either are part of mail servers, or pure mail exchangers. See messaging application protocols]] for further detail File Files are sequences of units of data. Structured data Remote procedure calls Character- or bit-oriented interaction Directory services Network management services Expectations of the end-to-end service Performance They may be tolerant or intolerant of impairments such as: Latency Bit errors Packet loss Sequencing of packets Security Endpoint authentication]] Client authentication Server authentication Peer authentication Data integrity Atomic integrity]] Sequential integrity]] Content confidentiality]] Traffic flow confidentiality]] Nonrepudiation]]