B345 Internet Science and Technology 
Week 10 lecture 2

Today's Lecture Learning Objective
- Understand the issues related to connecting a database to the web.
    - Specifically the 3-tier web application.

Data, Metadata and Programs
- Reminder from last lecture: 
    - Different types of "data" being passed at different levels.
    - Not clear what is "data" and what is not.

Basic 3-tier Web Application
- Why the 3-tiers?
- Alternatives:
    - No web front end?
    - No DBMS?
        - Data in web page content (text, images, sound, etc)
        - Data manipulation in server-side scripts
        - Data manipulation in client-side scripts

<< See Diagram A >>

Why DBMS?
- What a database management system can manage for your web app:
    - Efficient storage and retrieval
    - Data integrity
    - Multiple access control 
    - Transaction control
    - Crash recovery
- B218 and B334

Database Connectivity
- Technologies:
    - Proprietary APIs
    - ODBC
    - JDBC
    - ADO.NET
    - OLE DB

ODBC
- API for consistent access to different DBMS.
- ODBC drivers
- ODBC interface has
    - Standard way to connect to DBMS
    - Function calls to send SQL queries.
    - Standard data types

<< See Diagram B and C >>

Beyond Basic Connectivity
- .NET and ADO.NET
    - Towards distributed computing
- JDBC
    - Language and Java technology integration
- Do we need it?
    - Most of current problems in web app still is poor DB design and DBMS problems, rather than connectivity issues.

Deciding on the Connectivity Technology
- Which platform?
- What support in chosen DBMS?
- Proprietary or standard connectivity API?
    - For integration with other apps.
    - For easier development within and between projects.

Deciding on the DBMS
- Responsibilities of the DBMS
    - See earlier in the lecture. 
- Not the responsibility of the DBMS:
    - Interaction with the users.
    - Presentation of the results or responses.
    - Done by client and server-side scripts.

Easing the job of DBMS
- Scripts can:
    - Preprocess data (eg. validation).
    - Collate requests and queries.
    - Cache result.
- App development: deciding between
    - What the DBMS can do.
    - What the DBMS should do. 

Moving from small to large DBMS
- Small:
    - MS-Access
    - MySQL
- Large:
    - MS SQL Server
    - Oracle 9i
    - IBM DB2

Moving from small to large DBMS
- Gains in
    - Scalability, Performance, Manageability, Integration, Security, etc.
- Features
    - Difference in standard features closing fast.
    - Advanced features:
        - XML formats
        - Development tools
        - Web Services