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Web Technologies and Database Administration Systems

Web Technologies and Database Administration Systems. John Rowan. CS 8990, Summer 2004. The Internet & Information Sharing The emergence of the web as a way of sharing information has made it one of the fastest growing technologies.

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Web Technologies and Database Administration Systems

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  1. Web Technologies and Database Administration Systems John Rowan CS 8990, Summer 2004

  2. The Internet & Information Sharing The emergence of the web as a way of sharing information has made it one of the fastest growing technologies. It’s platform-independence make it appealing for applications and sharing data. The Database Management System (DBMS) has become the backbone for servicing data dynamically.

  3. The Internet: Brief History • Started in the late 60s early 70s as a project called Advanced Research Projects Agency Networks (ARPANET). • - U.S. Department of Defense • Uses suite of package switching called TCP/IP or Transmission Control Protocol and Internet Protocol in 1983

  4. The Internet: Brief History (cont) Has grown to support over 650 million users in over 100 countries. It is regulated bye the Internet Engineering Task Force or IETF. - Responsible for promoting standards - Harald T. Alvestrand is chairman Supports numerous protocols (TCP, FTP, SSH, PPP)

  5. Web/DBMS Integration Considerations • The ability to access valuable customer data in a secure manner. • Data and vendor independent connectivity to allow freedom of choice in the selection of the DBMS now and in the future. • The ability to interface to the database independent of any proprietary web browser or web server.

  6. Web/DBMS Integration Considerations (cont) • A connectivity solution that takes advantage of all the features of an organization’s DBMS. • An open-architecture approach to allow interoperability with a variety of systems and technologies; for example, support for - different web servers; • Microsoft’s (Distributed) Common Object Model (DCOM/COM) • CORBA/IIOP (Internet Inter-ORB protocol) • Java/RMI (Remote Method Invocation).

  7. Web/DBMS Integration Considerations (cont) • A cost-effective solution that allows for scalability, growth, and changes in strategic directions, and helps reduce the costs of developing and maintaining applications. • Support for transactions that span multiple HTTP requests. • Support for session and applications based authentication.

  8. Web/DBMS Integration Considerations (cont) • Acceptable performance. • Minimal administration overhead. • A set of high-level productivity tools to allow applications to be developed, maintained, and deployed with relative ease and speed. • Distributed applications • The integration of legacy applications into new systems. • The use of different programming languages to write new components.

  9. Current Web Application Communication Standards • Common Object Request Broker (CORBA) • Distributed Component Object Model (DCOM) • Simple Object Access Protocol (SOAP) • Remote Method Invocation (RMI)

  10. CORBA • A CORBA component is an object. • A CORBA class implements one or more CORBA interfaces • The execution locations is transparent to the client. • The server process advertises one or more named objects. The client process has no named objects.

  11. CORBA (cont) • Client access remote objects by the way of references that have the same interface as remote objects. They forward all method invocations to the server for remote object execution. • The CORBA ORB runs within every CORBA process for communicating with other ORBS. • The CORBA ORB acts like a message bus between objects.

  12. CORBA (cont) • The ORBs are able to communicate with each other by the use of a protocol known as the General Inter-Orb Protocol. • CORBA uses an Interface Definition Language (IDL) which enables the development of language-neutral interfaces that CORBA objects implements. • Language-specific compilers translate IDL into language-specific codes that are used to implement those interfaces.

  13. CORBA Illustration

  14. Remote Method Invocation (RMI) • It is used to access remote objects. • Java to Java only. • Uses the client-server protocol. • It is transparent and lightweight.

  15. RMI (cont) • Remote References, Stubs, Skeletons • Remote references invoked on client exactly like local object references. • Remote interfaces declare exposed methods. • Methods are implemented on the client. • Stubs are used on the client and pretends to be a remote object. • Skeleton lives on the server and it receives requests from the stub. The skeleton communicates with the remote object and delivers response to the server.

  16. RMI Illustration

  17. Simple Object Access Protocol • Lightweight-protocol used for exchange of messages in a decentralized, distributed environment. • Used for Remote Procedure Calls (RPC) • W3C defines the use of SOAP with XML as payload and HTTP as transport.

  18. SOAP Components • Envelope – Top element of the XML document representing the message. • Header – Optional layer that determines how a recipient of a SOAP message should process the message. Adds features to the SOAP message such as authentication, transaction management, message routing … etc. • Body – Used for RPC calls and error reporting. • Soap Fault – Used to carry error or status information within the SOAP Message.

  19. SOAP Components

  20. Advantages and Disadvantages • of SOAP, CORBA, and RMI • Advantages - SOAP • SOAP uses a widely known protocol for transport (HTTP). It is proven to be scalable. • It has a wide remote system interoperability. • Flexible for growth due to XML use. • Disadvantages – SOAP • Parsing of SOAP packet and mapping to objects reduces performance. • Doesn’t implement security because it is a wire protocol (relies on HTTP).

  21. Advantages and Disadvantages • of SOAP, CORBA, and RMI • Advantages – CORBA • Multi-language support. • Can start up more then one service for load balancing. • Different ORBs can communicate. • Easy to extend new languages. • Open standard developed by international consortium.

  22. Advantages and Disadvantages • of SOAP, CORBA, and RMI • Disadvantages – CORBA • Performance can be slow. • Implementations are still continually evolving. • Many ORBs do not provide full functionality of CORBA specifications. • Limited mainstream acceptance.

  23. Advantages and Disadvantages • of SOAP, CORBA, and RMI • Advantages – RMI • Simple implementation. • No IDL. • Can pass and return existing Java objects. • Comes with JDK – No ORBs to buy. • Java is free.

  24. Advantages and Disadvantages • of SOAP, CORBA, and RMI • Disadvantages – RMI • Not full-featured middleware. • No mechanism for object description. • No language independence.

  25. Other Web Technologies • Java Servlets & Java Server Pages • Common Gateway Interface (CGI) • Active Server Pages (ASP) • Perl • PHP • JavaScript & VBScript

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