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A computer that enables resource sharing by other computers on the same network.
The OSI Model :
•Protocol interaction
The OSI Model :
•Application layer protocols
•Top (seventh) OSI model layer •Does not include software applications •Protocol functions –Facilitates communication between software applications and lower-layer network services –Network interprets application request –Application interprets data sent from network•Software applications negotiate with application layer protocols
–Formatting, procedural, security, synchronization, and other requirementsExample of Application layer protocol: HTTP
•Model for understanding and developing network computer-to-computer communications •Developed by ISO in the 1980s •Divides network communications into seven layers –Physical, Data Link, Network, Transport, Session, Presentation, Application
•Protocol functions –Accept Application layer data –Format data •Understandable to different applications and hosts •Examples of file types translated at the presentation layer –GIF, JPG, TIFF, MPEG, QuickTime •Presentation layer services manage data encryption and decryption –Example protocol: Secure Sockets Layer (SSL)
•Protocol functions –Coordinate and maintain communications between two network nodes •Session –Connection for ongoing data exchange between two parties •Connection between remote client and access server •Connection between Web browser client and Web server
•Functions –Establishing and keeping alive communications link •For session duration –Keeping communications secure –Synchronizing dialogue between two nodes –Determining if communications ended •Determining where to restart transmission –Terminating communications –Set terms of communication –Identify session participants
