What TCP/IP Provides to Applications

TCP/IP provides 6 major features:

1. Connection orientation - for two programs to employ TCP/IP, one program must first request a connection to the destination before communication may proceed.

2. Reliable connection startup - when two applications create a connection, both must agree to the new connection. No packets from previous, or ongoing, connections will interfere.

3. Point-to-point communication - each communication session has exactly 2 endpoints.

4. Full-duplex communication - once established, a single connection may be used for messages in both directions.

   This requires buffering at both each input and output 'end', and enables each application to continue with computation while data is being communicated.

5. Stream interface - from the application's viewpoint, data is sent and received as a continuous sequence of bytes.

   Applications need not (but may) communicate using fixed-sized records. Data may be written and read in blocks of arbritary size.

6. Graceful connection shutdown - TCP/IP guarantees to reliably deliver all 'pending' data once a connection is closed by one of the endpoints.