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Component Based Systems Analysis Introduction. Why Components? t Development alternatives: –In-house software –Standard packages –Components 60% of the.

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Presentation on theme: "Component Based Systems Analysis Introduction. Why Components? t Development alternatives: –In-house software –Standard packages –Components 60% of the."— Presentation transcript:

1 Component Based Systems Analysis Introduction

2 Why Components? t Development alternatives: –In-house software –Standard packages –Components 60% of the functionality in a typical information system is the same for all organisations (IBM)

3 What is a Component? t “A component is a piece of software small enough to create and maintain, big enough to deploy and support and with standard interfaces for interoperability” (Jed Harris) t Components are executable

4 Component Models t Standard specification of how components should behave in a given environment –Versioning –Open tool palettes –Configuration management –Event notification –Metadata and introspection –Licensing

5 Levels of Components Customer, Product, Order, Currency Subscriber Telephone service Domain Components Technical Components General Business Components InsuranceTelecomAerospace GUI components Security services

6 Component Based Development Supply - Build new - Wrap existing - Buy Supply - Build new - Wrap existing - Buy Consume - Assemble applications Consume - Assemble applications Manage - Publish - Subscribe - Catalogue - Browse Manage - Publish - Subscribe - Catalogue - Browse

7 Objects and Components Analysis Design Construction Object oriented Component based A component does not have to be an object

8 Client/Server Architecture A server providing services A client requesting services ATMs Thin and fat clients

9 Advantages of Client/Server t Scalability –Horizontal, more clients –Vertical, more powerful server t Dedicated servers t Shared resources t Maintenance –Server centrally –Client locally

10 Three Level Architecture Data Presentation Application logic User interface provided via a browser Java servlets running on a server Data served from a DBMS Handles data from different sources within client/server

11 Distributed Objects t Objects encapsulate data and operations t Ordinary objects –Reside in a single program –Cease to be separate entities after compilation t Distributed objects –Reside anywhere on a network –Exist as physical standalone entities –Accessible by other objects

12 Middleware t Distributed software for supporting interaction between client and server; including client API, network transfer, and server response t Database middleware: ODBC, JDBC, … t Internet middleware: HTTP, … t Object middleware: CORBA, COM/DCOM, Enterprise JavaBeans,...

13 Application objects OMG Object Management Architecture Common facilities Object services Object Request Broker

14 Architectural Patterns t Context –Designing a living room t Problem –Making people feel comfortable t Forces –People want to sit down –People want to be close to the light t Solution –Put a sitting place close to the windows

15 Design Patterns t Context –Developing software with a human-computer interface t Problem –Interfaces vary often t Forces –Easy to modify the interface –Modifying the interface should not impact the application logic t Solution –Model-View-Controller

16 A Design Pattern - MVC Model core data notify getData View myModel display update Controller myView handleEvent update

17 Properties of Patterns t Address recurring problems t Document well-proven experience t Specify abstract solutions

18 Analysis Patterns Employment Period of Time Organisation Person A person is employed in an organisation for a period of time.

19 Analysis Patterns Management Role Period of Time Organisation Person A person has a certain management role for a period of time.

20 Analysis Patterns Marriage Period of Time Person Two people are married for a period of time.

21 Analysis Patterns Accountability Period of TimeOrganisationPerson One party is accountable to another party for something for a period of time. Accountability type Organisation

22 Course contents Analysis patterns Fowler Component models JavaBeans SanFrancisco DOT Java Servlets EJB CORBA COM/DCOM


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