The Session Layer
Electronic Conversations
A session between processes is like a conversation between people. Certain conventions in conversation help avoid confusion and allow for orderly and complete transfer of information between the parties. The conventions include:
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The parties first agree to talk to one another.
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They (usually) do not talk simultaneously.
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They divide the conversation into parts. ("Let me describe it to you, and you can tell me what you think.")
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They end the conversation in an orderly fashion. ("I will talk to you later." "Okay. Bye.")
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Similarly, the Session Layer provides higher layers with services that can be used to conduct sessions, including:
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Establishing a session (separately from a connection)
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Conducting dialogs that prevent both parties from transmitting data simultaneously
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Managing activities by dividing the session into parts
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Ending a session gracefully
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