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Distributed Object Computing. Team - A1 Williamson, MacFarlane, Crabtree. SOAP Introduction. Need exists for truly interoperable standards for object access. XML and HTTP provide perfect infrastructure.
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Distributed Object Computing Team - A1 Williamson, MacFarlane, Crabtree
SOAP Introduction • Need exists for truly interoperable standards for object access. • XML and HTTP provide perfect infrastructure. • SOAP – Simple Object Access Protocol provides a lightweight protocol for remote object access with an eye on extensibility and simplicity.
SOAP Process • Sender initiates communication using an HTTP post with XML (SOAP) content • Receiver processes SOAP message and returns result via HTTP response • Errors are returned as a SOAP Fault • SOAP allows for intermediaries
SOAP Structure • SOAP Envelope • The wrapper for the SOAP message • SOAP Header(s) • Contain processing information and requirements • Allows for application-specific extensibility • Used to instruct intermediaries • SOAP Body • Actual SOAP payload intended for the recipient • May contain SOAP Fault
SOAP & RPC • A non-vendor specific, non platform-specific way to conduct RPC • Represent method calls using specially-formatted SOAP XML • Supports advanced advanced language features such as polymorphism and function overloading
SOAP Extensions • WSDL • Web Services Description Language • A published interface for a web service • UDDI • Directory of web services • A searchable “yellow pages” of WSDL
What is an ORB • Stubs and Skel utilize IDL • IIOP is layered upon the Internet • ex: CORBA, DCOM, EJB
DCOM-General Info. • DCOM (Distributed Component Object Model), from Microsoft, is an extension of COM for distributed environments. • Provides client-server communications • Comes packaged with Windows Operating systems and is available for major UNIX platforms and IBM’s large server products. • DCOM replaces OLE Remote Automation.
DCOM-Technical Info. • Uses TCP/IP and HTTP • Object RPC (ORPC), an extension of the DCE RPC protocol, defines how remote procedure calls are made across a network.
Real-Time Configurability Predictability High Peformance Assurance of Correctness Resource Management Prioritization Issues Fault Tolerance Active/Passive Replication Network Recovery Fault Detection Rollback and Recovery Extending ORBs