[PPT] - 61A Lecture 33 Monday, November 25 Announcements 2 Announcements PowerPoint Presentation

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61A Lecture 33

Monday, November 25

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Announcements

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29
No discussion section Wednesday 11/27 through Friday 11/29

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29
No discussion section Wednesday 11/27 through Friday 11/29

Lab will be held on Wednesday 11/27

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29
No discussion section Wednesday 11/27 through Friday 11/29

Lab will be held on Wednesday 11/27

Recursive art contest entries due Monday 12/2 @ 11:59pm

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29
No discussion section Wednesday 11/27 through Friday 11/29

Lab will be held on Wednesday 11/27

Recursive art contest entries due Monday 12/2 @ 11:59pm
Guerrilla section about logic programming coming soon...

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Announcements

Homework 10 due Tuesday 11/26 @ 11:59pm
No lecture on Wednesday 11/27 or Friday 11/29
No discussion section Wednesday 11/27 through Friday 11/29

Lab will be held on Wednesday 11/27

Recursive art contest entries due Monday 12/2 @ 11:59pm
Guerrilla section about logic programming coming soon...
Homework 11 due Thursday 12/5 @ 11:59pm

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Addition in Logic

(Demo)

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Distributed Computing

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Distributed Computing

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

5

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.
Coordination is enabled by messages passed across a network.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.
Coordination is enabled by messages passed across a network.
Individual programs have differentiating roles.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.
Coordination is enabled by messages passed across a network.
Individual programs have differentiating roles.

Distributed computing for large-scale data processing:

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.
Coordination is enabled by messages passed across a network.
Individual programs have differentiating roles.

Distributed computing for large-scale data processing:

Databases respond to queries over a network.

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Distributed Computing

A distributed computing application consists of multiple programs running on multiple computers that together coordinate to perform some task.

Computation is performed in parallel by many computers.
Information can be restricted to certain computers.
Redundancy and geographic diversity improve reliability.

Characteristics of distributed computing:

Computers are independent — they do not share memory.
Coordination is enabled by messages passed across a network.
Individual programs have differentiating roles.

Distributed computing for large-scale data processing:

Databases respond to queries over a network.
Data sets can be partitioned across multiple machines (next lecture).

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Network Messages

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network.

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.
Transfer a program to be executed by another computer.

6

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.
Transfer a program to be executed by another computer.

Messages conform to a message protocol adopted by both the sender (to encode the message) & receiver (to interpret the message).

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.
Transfer a program to be executed by another computer.

Messages conform to a message protocol adopted by both the sender (to encode the message) & receiver (to interpret the message).

For example, bits at fixed positions may have fixed meanings.

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.
Transfer a program to be executed by another computer.

Messages conform to a message protocol adopted by both the sender (to encode the message) & receiver (to interpret the message).

For example, bits at fixed positions may have fixed meanings.
Components of a message may be separated by delimiters.

6

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Network Messages

Computers communicate via messages: sequences of bytes transmitted over a network. Messages can serve many purposes:

Send data to another computer
Request data from another computer
Instruct a program to call a function on some arguments.
Transfer a program to be executed by another computer.

Messages conform to a message protocol adopted by both the sender (to encode the message) & receiver (to interpret the message).

For example, bits at fixed positions may have fixed meanings.
Components of a message may be separated by delimiters.
Protocols are designed to be implemented by many different programming languages on many

different types of machines.

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Internet Protocol

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The Internet Protocol

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The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

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The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.

8

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The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.

8

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The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

8

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

8

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

IPv4

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All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet IPv4

8

All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports IPv4

8

All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports IPv4

8

E.g., 192.168.1.1 All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports The packet knows its size IPv4

8

E.g., 192.168.1.1 All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports The packet knows its size IPv4

8

Max length: 216 = 65,536 E.g., 192.168.1.1 All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports Packets can't survive forever The packet knows its size IPv4

8

Max length: 216 = 65,536 E.g., 192.168.1.1 All machines know IPv4

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Where to send the packet Where to send error reports Packets can't survive forever The packet knows its size IPv4

8

Max length: 216 = 65,536 E.g., 192.168.1.1 All machines know IPv4 Decremented

n forwarding

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http://en.wikipedia.org/wiki/IPv4

The Internet Protocol

The Internet Protocol (IP) specifies how to transfer packets of data among networks.

Networks are inherently unreliable at any point.
The structure of a network is dynamic, not fixed.
No system exists to monitor or track communications.

Packets are forwarded toward their destination on a best effort basis. Programs that use IP typically need a policy for handling lost packets. Where to send the packet Where to send error reports Packets can't survive forever The packet knows its size IPv4

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Max length: 216 = 65,536 E.g., 192.168.1.1 All machines know IPv4 Decremented

n forwarding

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Transmission Control Protocol

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Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

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Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.

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Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.

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Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

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Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

The receiver can correctly order packets that arrive out of order.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

The receiver can correctly order packets that arrive out of order. The receiver can ignore duplicate packets.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

The receiver can correctly order packets that arrive out of order. The receiver can ignore duplicate packets.

All received packets are acknowledged; both parties know that transmission succeeded.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

The receiver can correctly order packets that arrive out of order. The receiver can ignore duplicate packets.

All received packets are acknowledged; both parties know that transmission succeeded.
Packets that aren't acknowledged are sent repeatedly.

10

Transmission Control Protocol

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The design of the Internet Protocol (IPv4) imposes constraints:

Packets are limited to 65,535 bytes each.
Packets may arrive in a different order than they were sent.
Packets may be duplicated or lost.

The Transmission Control Protocol (TCP) improves reliability:

Ordered, reliable transmission of arbitrary byte streams.
Implemented using the IP. Every TCP connection involves sending IP packets.
Each packet in a TCP session has a sequence number:

The receiver can correctly order packets that arrive out of order. The receiver can ignore duplicate packets.

All received packets are acknowledged; both parties know that transmission succeeded.
Packets that aren't acknowledged are sent repeatedly.

The socket module in Python implements the TCP.

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Transmission Control Protocol

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TCP Handshakes

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.
The number of required messages is minimized.

11

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.
The number of required messages is minimized.

Communication Rules:

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.
The number of required messages is minimized.

Communication Rules:

Computer A can send an initial message to Computer B requesting a new connection.

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.
The number of required messages is minimized.

Communication Rules:

Computer A can send an initial message to Computer B requesting a new connection.
Computer B can respond to messages from Computer A.

11

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TCP Handshakes

All TCP connections begin with a sequence of messages called a "handshake" which verifies that communication is possible. "Can you hear me now?" Let's design a handshake protocol. Handshake Goals:

Computer A knows that it can send data to and receive data from Computer B.
Computer B knows that it can send data to and receive data from Computer A.
Lots of separate connections can exist without any confusion.
The number of required messages is minimized.

Communication Rules:

Computer A can send an initial message to Computer B requesting a new connection.
Computer B can respond to messages from Computer A.
Computer A can respond to messages from Computer B.

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Message Sequence of a TCP Connection

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Message Sequence of a TCP Connection

Computer A

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Message Sequence of a TCP Connection

Computer A Computer B

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement

Establishes packet numbering system

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement

Establishes packet numbering system

12

..

Data message from A to B Data message from B to A

..

Acknowledgement Acknowledgement

..

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement Termination signal

Establishes packet numbering system

12

..

Data message from A to B Data message from B to A

..

Acknowledgement Acknowledgement

..

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement Termination signal Acknowledgement & termination signal

Establishes packet numbering system

12

..

Data message from A to B Data message from B to A

..

Acknowledgement Acknowledgement

..

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement Termination signal Acknowledgement & termination signal Acknowledgement

Establishes packet numbering system

12

..

Data message from A to B Data message from B to A

..

Acknowledgement Acknowledgement

..

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Message Sequence of a TCP Connection

Computer A Computer B

Synchronization request Acknowledgement & synchronization request Acknowledgement Termination signal Acknowledgement & termination signal Acknowledgement

Establishes packet numbering system

12

..

Data message from A to B Data message from B to A

..

Acknowledgement Acknowledgement

..

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Client/Server Architecture

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The Client/Server Architecture

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The Client/Server Architecture

One server provides information to multiple clients through request and response messages.

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The Client/Server Architecture

One server provides information to multiple clients through request and response messages. Server role: Respond to service requests with requested information.

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The Client/Server Architecture

One server provides information to multiple clients through request and response messages. Server role: Respond to service requests with requested information. Client role: Request information and make use of the response.

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The Client/Server Architecture

One server provides information to multiple clients through request and response messages. Server role: Respond to service requests with requested information. Client role: Request information and make use of the response. Abstraction: The client knows what service a server provides, but not how it is provided.

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The Client/Server Architecture

One server provides information to multiple clients through request and response messages. Server role: Respond to service requests with requested information. Client role: Request information and make use of the response. Abstraction: The client knows what service a server provides, but not how it is provided.

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Client/Server Example: The World Wide Web

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

Interpret requests and respond with content.

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

Interpret requests and respond with content.

Web browser Web server

TCP Initialization Handshake

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

Interpret requests and respond with content.

HTTP GET request of content

Web browser Web server

TCP Initialization Handshake

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

Interpret requests and respond with content.

HTTP GET request of content HTTP response with content

Web browser Web server

TCP Initialization Handshake

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Client/Server Example: The World Wide Web

The client is a web browser (e.g., Firefox):

Request content for a location.
Interpret the content for the user.

The server is a web server:

Interpret requests and respond with content.

HTTP GET request of content HTTP response with content Follow-up requests for auxiliary content

...

Web browser Web server

TCP Initialization Handshake

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The Hypertext Transfer Protocol

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SLIDE 110

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture.

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The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture.

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The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Uniform resource locator (URL)

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SLIDE 113

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL)

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SLIDE 114

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL) Server response contains more than just the resource itself:

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SLIDE 115

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL) Server response contains more than just the resource itself:

Status code, e.g. 200 OK, 404 Not Found, 403 Forbidden, etc.

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SLIDE 116

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL) Server response contains more than just the resource itself:

Status code, e.g. 200 OK, 404 Not Found, 403 Forbidden, etc.
Date of response; type of server responding

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SLIDE 117

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL) Server response contains more than just the resource itself:

Status code, e.g. 200 OK, 404 Not Found, 403 Forbidden, etc.
Date of response; type of server responding
Last-modified time of the resource

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SLIDE 118

The Hypertext Transfer Protocol

The Hypertext Transfer Protocol (HTTP) is a protocol designed to implement a Client/ Server architecture. Browser issues a GET request to a server at www.nytimes.com for the content (resource) at location "pages/todayspaper". Uniform resource locator (URL) Server response contains more than just the resource itself:

Status code, e.g. 200 OK, 404 Not Found, 403 Forbidden, etc.
Date of response; type of server responding
Last-modified time of the resource
Type of content and length of content

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SLIDE 119

Properties of a Client/Server Architecture

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SLIDE 120

Properties of a Client/Server Architecture

Benefits:

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SLIDE 121

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.

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SLIDE 122

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.

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SLIDE 123

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

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SLIDE 124

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

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SLIDE 125

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.

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SLIDE 126

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.
Computing resources become scarce when demand increases.

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SLIDE 127

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.
Computing resources become scarce when demand increases.

Common use cases:

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SLIDE 128

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.
Computing resources become scarce when demand increases.

Common use cases:

Databases — The database serves responses to query requests.

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SLIDE 129

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.
Computing resources become scarce when demand increases.

Common use cases:

Databases — The database serves responses to query requests.
Open Graphics Library (OpenGL) — A graphics processing unit (GPU) serves images to a

central processing unit (CPU).

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SLIDE 130

Properties of a Client/Server Architecture

Benefits:

Creates a separation of concerns among components.
Enforces an abstraction barrier between client and server.
A centralized server can reuse computation across clients.

Liabilities:

A single point of failure: the server.
Computing resources become scarce when demand increases.

Common use cases:

Databases — The database serves responses to query requests.
Open Graphics Library (OpenGL) — A graphics processing unit (GPU) serves images to a

central processing unit (CPU).

Internet file and resource transfer: HTTP, FTP, email, etc.

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SLIDE 131

Peer-to-Peer Architecture

SLIDE 132

The Peer-to-Peer Architecture

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SLIDE 133

The Peer-to-Peer Architecture

All participants in a distributed application contribute computational resources: processing, storage, and network capacity.

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SLIDE 134

The Peer-to-Peer Architecture

All participants in a distributed application contribute computational resources: processing, storage, and network capacity. Messages are relayed through a network of participants.

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SLIDE 135

The Peer-to-Peer Architecture

All participants in a distributed application contribute computational resources: processing, storage, and network capacity. Messages are relayed through a network of participants. Each participant has only partial knowledge of the network.

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SLIDE 136

The Peer-to-Peer Architecture

All participants in a distributed application contribute computational resources: processing, storage, and network capacity. Messages are relayed through a network of participants. Each participant has only partial knowledge of the network.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 137

Network Structure Concerns

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 138

Network Structure Concerns

Some data transfers on the Internet are faster than others.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 139

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 140

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 141

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 142

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 143

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 144

Network Structure Concerns

Some data transfers on the Internet are faster than others. The time required to transfer a message through a peer-to-peer network depends on the route chosen.

http://en.wikipedia.org/wiki/File:P2P-network.svg

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SLIDE 145

Example: Skype

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SLIDE 146

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture.

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SLIDE 147

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server.

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SLIDE 148

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes.

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SLIDE 149

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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SLIDE 150

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A

SLIDE 151

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A Client B

SLIDE 152

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A Client B Clients behind firewalls cannot communicate directly

SLIDE 153

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A Client B Client C Clients behind firewalls cannot communicate directly

SLIDE 154

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A Client B Client C A client not behind a firewall may be used as a supernode Clients behind firewalls cannot communicate directly

SLIDE 155

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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Client A Client B Client C A client not behind a firewall may be used as a supernode Clients behind firewalls cannot communicate directly

SLIDE 156

Example: Skype

Skype is a Voice Over IP (VOIP) system that uses a hybrid peer-to-peer architecture. Login & contacts are handled via a centralized server. Conversations between two computers that cannot send messages to each other directly are relayed through supernodes. Any Skype client with its own IP address may be a supernode.

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