Web Services Software Architecture RFI Response

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Web Services Software Architecture RFI Response

• Eric Newcomer Rebecca Bergersen
• May 28, 2003

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Summary

• OMG is not in a position to establish a Web
  Services Architecture
• WSA working group already exists at W3C
• Liaise with Web services working groups instead
• OMG can contribute towards the realization of the
  architecture
• Define Web services mappings for CORBA services
• Create integrations for related CORBA, EJB, Web
  services specifications
• Define GIOP bindings for SOAP
• Fix UML and MDA to work better with Web services

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Web Services Architecture

• Compare and contrast OMG efforts with W3Cs WSA
• Ensure complementary activities and eliminate
  duplication of effort
• Add value where needed with OMG expertise
• OMG establishing a WSA is at odds with the
  industry
• This work is already underway at W3C
• OMG alignment with W3C, OASIS, WS-I, JCP is
  essential, instead
• OMG cannot realistically tackle WSA now

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WS mappings for CORBA services

• Security
• Define how CSIv2 tokens can be used within
  WS-Security framework
• Define mapping of CS1v2 to additional formats
  used in WS
• Transactions
• Bridge OTS to WS-Transactions
• Map Activity Spec to WS-Coordination
• Notification
• Define pub/sub message exchange patterns for Web
  services (we have a draft spec)
• AMI
• Define store and forward mechanism for pickling
  SOAP requests (we have some technology in this
  area)

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Integrations across CORBA, J2EE, WS

• Web services mappings tend to be 1-1
• WSDL to IDL
• SOAP to JAX-RPC
• WSDL to EJB
• But what about mixed language environments
• C to Java
• COBOL to PL/I
• Perl to Python?
• What about mixed paradigms and services across
  them all?

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GIOP bindings for SOAP

• Web services are designed to be multi-protocol
  compatible
• Yet standard bindings are effectively limited to
  HTTP
• What about bindings for IIOP, FTP, SMTP, JMS,
  Notification?
• No one is working on this
• Is the GIOP model applicable?
• Can we reuse the abstractions?
• Is there something we can do about persistent
  sessions for HTTP?

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Fix UML and MDA for WS

• Web services are data-oriented, not
  object-oriented
• UML and MDA are object-oriented
• Class diagrams are not well suited to modeling
  Web services
• Web services design starts with the message, or
  schema for the message not with the interface
• Interaction diagrams can be used but they are
  limited in terms of the information they can
  capture

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Common understanding of WS

• Web services are not executable
• They are applications of XML
• XML is a document markup language
• Documents, schemas, and transformations are
  interpreted, not compiled
• Web services are mapped into and out of
  executable agents
• Non functional requirements such as
  scalability, availability, etc. are out of scope
• Traditional architectures do not directly apply

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Design center for WSA

• Its all about the overlay
• XML and HTTP have broadsided distributed
  computing systems
• The success of the Web cannot be questioned
• Therefore we must adopt and adapt
• Web services are kind of retro
• Back to text and file based interaction
• No persistent sessions or CORBA services
• OMG has a lot to offer services, GIOP, UML/MDA