HyperText Transfer Protocol Nicolas Rogemond T-110.456 : Next - - PowerPoint PPT Presentation

Nicolas Rogemond 09/02/2005 1

HyperText Transfer Protocol

Nicolas Rogemond

T-110.456 : Next generation cellular networks

Nicolas Rogemond 09/02/2005 2

Introduction

Definition

• HTTP is defined in RFC 2068 as

“an ubiquitous application level protocol for distributed, collaborative, hypermedia information systems”

• HTTP is a stateless object-oriented protocol

(i.e. does not require the client and the server to keep track and state of messages exchanged)

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Introduction

History

HTTP was first proposed by Tim Berners-Lee at CERN in order to help researchers navigate through the number of research papers and project at the laboratory.

January 1992 HTTP/0.9 March 1993 HTTP/1.0 first Draft November 1993 HTTP/1.0 second Draft March 1996 HTTP/1.0 informational, RFC 1945 January 1997 HTTP/1.1 proposed standard, RFC 2068 June 1999 HTTP/1.1 draft standard, RFC 2616 June 2001 HTTP/1.1 formal standard RFC 2068

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Improvements

The main goals of the HTTP/1.1 is to remove any inconsistency and resolve the inter-operability issues that exploded with the previous version of the HTTP

• Consistent request and response methods
• Persistent connections
• Chunked encoding
• Content negotiation
• Digest authentication
• New headers
• Byte range operation

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Improvements

Consistent request and response methods

In addition to the GET, HEAD and POST methods of HTTP/1.0, HTTP/1.1 defined and finalized the semantics of 5 new methods request types :

» DELETE » PUT » OPTIONS » TRACE » CONNECT

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Improvements

Persistent connections

• Persistent connection as default

behaviour

• Pipelining

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Improvements

Chunked encoding

• In HTTP, it is very important to indicate the

length of the response message being sent to be sure that no loss occurs during the transfer

• HTTP/1.0 indicates the length of the

message by closing the connection after transmitting the full message

• HTTP/1.1 uses a “Content-length” field in

the header and if needed (e.g. dynamic generated answers) the Chunked encoding

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Improvements

Content negotiation HTTP/1.1 defines 2 types of content negotiation :

• Server driven (based on client’s request) :

the server will choose the appropriate format and representation of the resource according to the request headers and/or the client IP

• Agent driven : this occurs when the server

provides the user agent alternatives to the available resource. It is up to the user agent to indicate the best representation

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Improvements

Digest authentication

• The digest authentication is an other

security layer in addition to the “basic authentication” one

• The principle is the same (based on

username and password) but in this

• ne, the “keys” are encrypted.

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Improvements

Headers

• HTTP headers are metadata that describe the

resource being sent. They play a major role in HTTP specification and implementation in that way they extend the capabilities of the protocol

• HTTP/1.1 classified 4 types of headers :
• General headers
• Entity headers
• Request headers
• Response headers

End to End headers Hop by Hop headers

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Improvements

Byte range operation

Byte range operation allows client to download a range of bytes instead of the entire document, the consequences are :

– Recovery from failed transfers – Multiple transfers of the same document as the same time – Work with small parts of large documents without completely downloading them

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Competing Technology : MHSP

• MHSP (Multiple Hypertext Stream Protocol)
• MHSP is a full-duplex, symmetric protocol

that the proxy uses to communicate with wireless clients. It is designed to reduce latency while allowing the client to take advantage of available bandwidth

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Competing Technology : MHSP

MHSP has the following features :

– maintains a permanent connection – transfers more than one file simultaneously – allows both clients and proxy to initiate and stop file transfers – tracks the progress of file transfers, allowing stopped transfers to be resumed – maintains compatibility with existing networks by running on top of TCP

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Application for mobile telecommunications

• All WML (Wireless Mark-up Language)

content is accessed over the Internet using standard HTTP/1.1 requests

• WAP 2.0

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What’s next?

HTTP/NG (New Generation)

• The World Wide Web Consortium (W3C) and

Internet Engineering Task Force (IETF) are actively working with the WAP Forum to evolve HTTP-NG to better meet the requirements of future wireless network technologies (3G wireless network)

• HTTP-NG is a comprehensive rethinking of the

Web’s underlying protocol. It provides a framework for defining new Web applications, a powerful messaging system, and a multiplexing transport layer

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HTTP/NG

• 3 layer architecture :

– Transport Layer – Messaging Layer – Application Layer Performances comparisons

Realized with W3C Microscape benchmark

HTTP/NG 0.19sec HTTP/1.1 Pipelined 0.23sec CORBA’s IIOP 1.0 0.58sec

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Conclusion

• HTTP/1.1 has been developed to

facilitate the convergence between mobile communication (2G/3G) and the fixed networks

• HTTP & HTML were the basis of the

web’s rapid growth in the early 90’s, HTTP/1.1 can be the basis of the growth of mobile communication

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End of the lecture

Thanks for your attention