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25 Cards in this Set
- Front
- Back
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Application Layer Protocols defintion
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Types of messages exchanged, syntax and semantics of message, the rules for when and how messages are sent
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Socket Programming
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programming model used in constructing distributed systems, socket is a programming interface
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Protocol design issues
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in band vs. out of band control signaling (in header or not) Push vs Pull, Persistent vs non-persistant connections
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Client
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initiates contact with server (speaks first) Requests service from sender, for Web, client is implemented in browser, email mail client
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Server
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Provides requested service to client. "Always" running under the socket model.
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About Socket
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sockets created and managed by applications, fundamental building blocks of client and server systems. interface into which an opplication process can both send and reciebe messages to/from another remote or local application process
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UDP Sockets
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unreliable, datagram oriented communications
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TCP sockets
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reliable, strem-oriented communications
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Sockets Addressed
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using an IP Address and port number
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3 Way Handshake
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Client socket establishes connection, gets welcoming socket, then creates connection socket and sends information through.
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TCP Service
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connection-oriented: a setup is required. Reliable transport between sending and reciving. Flow control: snder wont overwhelm reciever, congestion control
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TCP Does not provide
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timing, minimum bandwidth guarantees
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UDP Service
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unriable data transfer between sending and reciving process
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UDP Does not provide
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connection setup, reliability, flow control, congestion control, timing, min bandwidth guarantees
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Why UDP?
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More effecient, small advantages in specific instances
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Application
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Communicating, distributed processes, Exchange mssages to implement application
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HTTP
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Hypertext transfer protocol
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HTTP Client Server
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client, browser that requests and recives web objects, Server web server sends objects
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Stateless
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HTTP is statless, server maintains no information about past browsre requests
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HTTP Uses
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TCP sockets, browser initiates TCP connection
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HTTP 1.0
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One request/response interaction per connection
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HTTP 1.1
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persistent connections, pipelined connections
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Objects
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Browser makes seperate requests for all the objects on a webpage
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Request HTTP message
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Request line, optional headers, body for some methods (POST)
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Response HTTP message
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request line, ASCII format, optional header. Requested object or error message
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