1. TM 8-1 Copyright © 1999 Addison Wesley Longman, Inc. Client/Server and Middleware

2. TM 8-2 Copyright © 1999 Addison Wesley Longman, Inc. Database server architecture

3. TM 8-3 Copyright © 1999 Addison Wesley Longman, Inc. Three-tier architecture

4. TM 8-4 Copyright © 1999 Addison Wesley Longman, Inc. Client/Server Architectures Personal computers. Local area network (LAN). Share common devices. –Server. –Printer. Share software (e.g. a DBMS).

5. TM 8-5 Copyright © 1999 Addison Wesley Longman, Inc. Components of Application Logic Input/Output or Presentation Logic –Manage user input from the keyboard. –Format and present data on the screen. Processing Component –Data validation. –Business rules (not coded at DBMS level.) –Identifies the data necessary for the transaction. Storage Component –Data storage and retrieval.

6. TM 8-6 Copyright © 1999 Addison Wesley Longman, Inc. File Server Architecture All processing is done at the PC that requested the data (“fat client”). Entire files are transferred from the server to the client for processing. Problems –Requires fat clients. –Huge amount of data transfer on the network.

7. TM 8-7 Copyright © 1999 Addison Wesley Longman, Inc. Database Server Architectures Client is responsible for I/O processing logic and business rules logic. Server performs all data storage and access processing. Advantages –Clients do not have to be as powerful. –Greatly reduced data traffic on the network. –Improved data integrity since it is all processed centrally.

8. TM 8-8 Copyright © 1999 Addison Wesley Longman, Inc. Three-Tier Architectures Client database. LAN server database. Enterprise database.

9. TM 8-9 Copyright © 1999 Addison Wesley Longman, Inc. Middleware Software which allows an application to work with other, otherwise incompatible, software. Application Program Interface (API) allows otherwise incompatible application development tools and databases to communicate.