HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 1

HTTP - Next GenerationHTTP - Next Generation

Mike Spreitzer

Xerox PARC CSL

8 June 1998

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 2

Problems with HTTPProblems with HTTP

Difficulty of extending/modifying HTTP Emerging incompatible object systems HTTP used as a reliable datagram protocol Increased use of CGI-like Web services Performance

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 3

The W3C HTTP-NG ProjectThe W3C HTTP-NG Project An activity of the World Wide Web

Consortium Experimental: What happens if we factor

HTTP into distributed-object system + application?

»original HTTP attempted a distributed object protocol

Goals: greater extensibility, simplicity, functionality, efficiency

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 4

Project StructureProject Structure

Two working groups– Web Characterization Group

» Jim Pitkow, Xerox PARC, chair»Study Web usage and form requirements

– Protocol Design Group» Jim Gettys, Digital, chair»Redesign Web as a distributed object

application

– Interest Group»www.w3.org/Protocols/HTTP-NG/Group/IG/

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 5

HTTP-NG ArchitectureHTTP-NG Architecture

Application (s)

Application Interface Stubs

Messaging Protocol

Transport

Stacks

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 6

Three Layer StructureThree Layer Structure

Web API layer on top offers object-oriented access to the classic Web operations

Messaging layer in middle provides state-of-the-art distributed object capabilities

Modular architecture for stackable byte transport layers– MUX layer addresses TCP/IP problems

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 7

Web Application LayerWeb Application Layer

Object-oriented network API for the HTTP 1.1 specification

The Classic Web Application (TCWA) Still under development

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 8

Messaging LayerMessaging Layer

Simple marshalling rules Small but powerful type system

»Combines Java RMI, CORBA, DCOM

Byte-efficient Uses session-adaptive compression Based on existing IETF standards and

registries

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 9

MUX LayerMUX Layer

Multiplexing multiple streams over single TCP/IP connection

Byte streams or opaque message streams Bi-directional over same TCP/IP

connection

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 10

Advantages of HTTP-NGAdvantages of HTTP-NG

Efficiency Extensibility Simplicity

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 11

EfficiencyEfficiency

MUX provides for state-sharing between multiple parallel connections

Binary message formats reduce the amount of string parsing and formatting needed, and typically reduce bytes on wire

Careful protocol design minimizes network round trips

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 12

ExtensibilityExtensibility

New interfaces can be defined to add new applications such as WebDAV

Backwards compatibility of interfaces allowed via subtyping of object types

HTTP+PEP’s optional/mandatory End-to-End/Hop-by-Hop headers mechanism available via property list groups

» Ideas on better typing too

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 13

Extensibility (2)Extensibility (2)

Extensibility in transport layer with transport stacking to transform message streams

Extensibility in messaging layer with extension contexts

Extensibility in application layer with interface definition, subtyping, etc.

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 14

SimplicitySimplicity

Highly modular architecture Low coupling between modules Each module designed to be internally

simple Predictable architecture

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 15

Relationship with XMLRelationship with XML

XML is important in the web HTTP-NG will use XML as appropriate

– Plan to develop an RDF-based IDL– DOM is getting IDL, Java interfaces;

hope to add HTTP-NG interfaces

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 16

Project Phase 1Project Phase 1 W3C Activity Demonstrate basic feasibility

– using existing ILU as testbed– new MUX and messaging protocols– robotic clients and modified Apache

First release of drafts in early July Ends this summer

– road show ready for September TC mtg

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 17

Project Phase 2Project Phase 2

Starting this summer W3C Activity continues (if approved) IETF involvement begins

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 18

Come Join Us!Come Join Us!

http://www.w3.org/Protocols/HTTP-NG/

– W3C members can see all– Others can join the Interest Group

Next IETF– August 23--28, Chicago