The Application layer of the OSI model is where users communicate to the
computer. The Application layer is responsible for identifying and establishing the availability of the intended communication partner and determining
if sufficient resources for the intended communication exist.
Although computer applications sometimes require only desktop
resources, applications may unite communicating components from more
than one network application; for example, file transfers, e-mail, remote
access, network management activities, client/server processes, and information location. Many network applications provide services for communication over enterprise networks, but for present and future internetworking,
the need is fast developing to reach beyond their limits.
Today, transactions and information exchanges between organizations are broadening to require internetworking applications like the following:
are multimedia and include some or all of the following: graphics, text,
video, and even sound. Netscape Navigator, Internet Explorer, and other
browsers like Mosaic simplify both accessing and viewing Web sites.
E-mail gateways Are versatile and can use Simple Mail Transfer Protocol (SMTP) or the X.400 standard to deliver messages between different e-mail applications.
Electronic Data Interchange (EDI): Is a composite of specialized standards and processes that facilitates the flow of tasks such as accounting, shipping/receiving, and order and inventory tracking between businesses.
Special interest bulletin : boards Include the many Internet chat rooms
where people can connect and communicate with each other either by
posting messages or by typing a live conversation. They can also share
public domain software.
Internet navigation utilities: Include applications like Gopher and
WAIS, as well as search engines like Yahoo!, Excite, and Alta Vista, which
help users locate the resources and information they need on the Internet.
Financial transaction services : Target the financial community. They
gather and sell information pertaining to investments, market trading,
commodities, currency exchange rates, and credit data to their subscribers.
computer. The Application layer is responsible for identifying and establishing the availability of the intended communication partner and determining
if sufficient resources for the intended communication exist.
Although computer applications sometimes require only desktop
resources, applications may unite communicating components from more
than one network application; for example, file transfers, e-mail, remote
access, network management activities, client/server processes, and information location. Many network applications provide services for communication over enterprise networks, but for present and future internetworking,
the need is fast developing to reach beyond their limits.
Today, transactions and information exchanges between organizations are broadening to require internetworking applications like the following:
World Wide Web (WWW) Connects countless servers (the number
seems to grow with each passing day) presenting diverse formats. Mostare multimedia and include some or all of the following: graphics, text,
video, and even sound. Netscape Navigator, Internet Explorer, and other
browsers like Mosaic simplify both accessing and viewing Web sites.
E-mail gateways Are versatile and can use Simple Mail Transfer Protocol (SMTP) or the X.400 standard to deliver messages between different e-mail applications.
Electronic Data Interchange (EDI): Is a composite of specialized standards and processes that facilitates the flow of tasks such as accounting, shipping/receiving, and order and inventory tracking between businesses.
Special interest bulletin : boards Include the many Internet chat rooms
where people can connect and communicate with each other either by
posting messages or by typing a live conversation. They can also share
public domain software.
Internet navigation utilities: Include applications like Gopher and
WAIS, as well as search engines like Yahoo!, Excite, and Alta Vista, which
help users locate the resources and information they need on the Internet.
Financial transaction services : Target the financial community. They
gather and sell information pertaining to investments, market trading,
commodities, currency exchange rates, and credit data to their subscribers.
The application layer of the OSI model is the layer that is closest to the user. Instead of providing services to other OSI layers, it provides services to application programs outside the scope of the OSI model. It's services are often part of the application process. Main functions are:-
• identifies and establishes the availability of the intended communication partner.
• synchronizes the sending and receiving applications.
• establishes agreement on procedures for error recovery and control of data integrity.
• determines whether sufficient resources for the intended communications exist.
• synchronizes the sending and receiving applications.
• establishes agreement on procedures for error recovery and control of data integrity.
• determines whether sufficient resources for the intended communications exist.
Devices:-
• Browsers
• Search engines
• E-mail programs
• Newsgroup and chat programs
• Transaction services
• Audio/video conferencing
• Search engines
• E-mail programs
• Newsgroup and chat programs
• Transaction services
• Audio/video conferencing
• Telnet
• SNMP
The following protocols are explicitly mentioned ,describing the application layer of the Internet protocol suite
- Remote login category
- Telnet
- SSH
- File transfer category
- FTP
- TFTP
- Electronic mail category
- SMTP
- IMAP
- POP
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