HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 1 HTTP - 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 HTTP l Difficulty of extending/modifying HTTP l Emerging incompatible object systems l HTTP used as a reliable datagram protocol l Increased use of CGI-like Web services l Performance

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 3 The W3C HTTP-NG Project l An activity of the World Wide Web Consortium l Experimental: What happens if we factor HTTP into distributed-object system + application? »original HTTP attempted a distributed object protocol l Goals: greater extensibility, simplicity, functionality, efficiency

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 4 Project Structure l 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 » NG/Group/IG/

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 5 HTTP-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 Structure l Web API layer on top offers object-oriented access to the classic Web operations l Messaging layer in middle provides state- of-the-art distributed object capabilities l 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 Layer l Object-oriented network API for the HTTP 1.1 specification l The Classic Web Application (TCWA) l Still under development

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 8 Messaging Layer l Simple marshalling rules l Small but powerful type system »Combines Java RMI, CORBA, DCOM l Byte-efficient l Uses session-adaptive compression l Based on existing IETF standards and registries

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 9 MUX Layer l Multiplexing multiple streams over single TCP/IP connection l Byte streams or opaque message streams l 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-NG l Efficiency l Extensibility l Simplicity

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 11 Efficiency l MUX provides for state-sharing between multiple parallel connections l Binary message formats reduce the amount of string parsing and formatting needed, and typically reduce bytes on wire l Careful protocol design minimizes network round trips

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 12 Extensibility l New interfaces can be defined to add new applications such as WebDAV l Backwards compatibility of interfaces allowed via subtyping of object types l 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) l Extensibility in transport layer with transport stacking to transform message streams l Extensibility in messaging layer with extension contexts l Extensibility in application layer with interface definition, subtyping, etc.

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 14 Simplicity l Highly modular architecture l Low coupling between modules l Each module designed to be internally simple l Predictable architecture

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 15 Relationship with XML l XML is important in the web l 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 1 l W3C Activity l Demonstrate basic feasibility –using existing ILU as testbed –new MUX and messaging protocols –robotic clients and modified Apache l First release of drafts in early July l 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 2 l Starting this summer l W3C Activity continues (if approved) l IETF involvement begins

HTTP-NG Briefing at Internet PSIG meeting, 8 June 1998; Mike Spreitzer, Xerox PARC 18 Come Join Us! l –W3C members can see all –Others can join the Interest Group l Next IETF –August , Chicago