lect4 - Chapter 2 Application Layer 2 Application Layer 1 Chapter 2 Application layer 2.1 Principles of network applications 2.2 Web and HTTP 2.3 FTP

lect4 - Chapter 2 Application Layer 2 Application Layer 1...

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2: Application Layer 1 Chapter 2 Application Layer
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2: Application Layer 2 Chapter 2: Application layer 2.1 Principles of network applications 2.2 Web and HTTP 2.3 FTP 2.4 Electronic Mail SMTP, POP3, IMAP 2.5 DNS 2.6 P2P applications
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2: Application Layer 3 Chapter 2: Application Layer Our goals: conceptual, implementation aspects of network application protocols transport-layer service models client-server paradigm peer-to-peer paradigm learn about protocols by examining popular application-level protocols HTTP FTP SMTP / POP3 / IMAP DNS
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2: Application Layer 4 Some network apps e-mail web instant messaging remote login P2P file sharing multi-user network games streaming stored video clips voice over IP real-time video conferencing grid computing
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2: Application Layer 5 Creating a network app write programs that run on (different) end systems communicate over network e.g., web server software communicates with browser software No need to write software for network-core devices Network-core devices do not run user applications applications on end systems allows for rapid app development application transport network data link physical application transport network data link physical application transport network data link physical
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2: Application Layer 6 Chapter 2: Application layer 2.1 Principles of network applications 2.2 Web and HTTP 2.3 FTP 2.4 Electronic Mail SMTP, POP3, IMAP 2.5 DNS 2.6 P2P applications
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2: Application Layer 7 Application architectures Client-server Peer-to-peer (P2P) Hybrid of client-server and P2P
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2: Application Layer 8 Client-server architecture server: always-on host permanent IP address server farms for scaling clients: communicate with server may be intermittently connected may have dynamic IP addresses do not communicate directly with each other client/server
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2: Application Layer 9 Pure P2P architecture no always-on server arbitrary end systems directly communicate peers are intermittently connected and change IP addresses Highly scalable but difficult to manage peer-peer
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2: Application Layer 10 Hybrid of client-server and P2P Skype voice-over-IP P2P application centralized server: finding address of remote party: client-client connection: direct (not through server) Instant messaging chatting between two users is P2P centralized service: client presence detection/location user registers its IP address with central server when it comes online user contacts central server to find IP addresses of buddies
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2: Application Layer 11 Processes communicating Process: program running within a host. within same host, two processes communicate using inter-process communication (defined by OS). processes in different hosts communicate by exchanging messages Client process: process that initiates communication Server process: process that waits to be contacted Note: applications with P2P architectures have client processes & server processes
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2: Application Layer 12 Sockets process sends/receives
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  • Spring '17
  • IP address, Web server, Hypertext Transfer Protocol

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