1. Web Technology and DBMS’s (CB 29)
CPSC 356 Database Design
Ellen Walker
Hiram College
(Includes figures from Database Systems by Connolly & Begg, © Addison Wesley 2005)

2. What is the Internet? Interconnected Networks History
Interoperable via standards (TCP, IP)
History
ARPANet (late 60’s, early 70’s) - military
NSF took over, provided funding (1986)
Commercial backbones ( present)

3. Internet vs. Intranet Internet Intranet Typically, limited interaction
Global, open, public
Called “extranet” to distinguish from Intranet
Intranet
Private network for exclusive use of an organization
Behind a firewall
Typically, limited interaction

4. Internet Evolution of a Business (Cisco)
Web site
E-Commerce
Customers can place and pay for orders via web
E-Business
Complete integration of Internet technology into business’s infrastructure
Ecosystem
Entire business process automated - customers, suppliers, alliance partners, corporate infrastructure merged into seamless system

5. Web vs. Internet
Internet provides infrastructure of information transmission across the network
Web contains interlinked information (web pages)
Servers: contain pages and transmit on request
Clients (browsers): request and display pages to users

6. Languages of the Web
HTTP - protocol for sending / receiving web pages. Includes GET vs. POST
HTML - basic markup language (represents complex pages as text). Includes mechanism (href) to reference other pages.
XML - extended markup language - generalization of HTML to represent more complex document information
(etc) -- this is not a complete list!

7. Limitations of HTTP
Each transaction consists of a single request for data and a single response.
GET = request data
POST = response (or data from form)
Protocol is “stateless” - does not retain information beteween transactions
Workarounds: cookies or hidden text

8. Static vs. Dynamic Web Page
Static web page
Contents of page stored in a file, served as originally written
Dynamic web page
Generated as needed
Only instructions for generating the page are stored (e.g. php query/display based on argument)

9. Dynamic Web Pages
Input provided as parameters or from forms in the page
Data generated from queries
Pages written in a “scripting language” (PHP is one example)

10. Requirements for Web-DBMS Integration
Ability to maintain data security
Not tied to a single DBMS
Not tied to a single browser
Availability of all features of DBMS
Open-architecture approach, supporting multiple servers, standard interoperability languages (e.g. DCOM, CORBA, XML, SOAP)

11. Advantages of Web Approach
Simplicity
Platform independence
Graphical User Interface
Standardization
Transparent network access
Simplified deployment
Global access

12. Disadvantages (lack of) Reliability (lack of) Security Cost (!)
Heavy (unpredictable) loads
HTML limitations
Bandwidth & Performance limitations
Immaturity of platform & tools

13. Tools to Integrate the Web
Scripting Languages
Client-side or Server-side
Common Gateway Interface (CGI)
Server-side
Web server extensions
Java, J2EE, SQLJ, etc.
Microsoft .Net
Oracle’s Internet platform

14. Scripting languages Programs embedded in HTML files on server
Behavior of all clients changed by changing script on server
Scripts are generally interpreted, not compiled

15. JavaScript Server-side or Client-side (client-side more common)
Allows immediate reaction to user interface widgets
Object-based (Document Object Model)
Limited relative to Java
(VBScript : Visual Basic = JavaScript : Java)

16. Perl, PHP Server side languages
Heavy Unix flavor (e.g. use of regular expressions)
PHP preferred for Linux
Integrates with Apache HTTP Server
Works well with MySQL or PostgreSQL

17. Common Gateway Interface (CGI)
Defines how scripts communicate with web servers
Uses Environment variables, standard I/O on server side
Uses HTML Forms on client side (original impetus for forms)
Nearly any programming language can run on server (std. output returned to browser)
Server runs script based on filename (x.cgi, x.php, etc) - this is configurable

18. CGI Environment

19. Advantages of CGI Standardized interface
Programming-language independent
Web-server independence
Simplicity
Wide acceptance

20. Disadvantages of CGI Web server can be bottleneck
Problems from HTTP Statelessness
No validation of user input (must go “back” to repopulate form)
No transactions (must connect to database on every page)
Security risks
Scripts with greater privileges than server
Risk of unanticipated (or malicious) user input

21. HTTP Cookies Stored by browser in a file on client
Cookies set / retrieved by HTTP request
Issues:
Not supported by all browsers
For privacy reasons, users disable cookies

22. Non-CGI Gateways API Extensions to server (NSAPI, ISAPI)
Scripts loaded as part of server
Direct interaction with back end
One copy per server, not per request
Changes server executable (risk?)
Requires specialized programmers

23. Vendor Specific Scripting
Developed by vendors as server add-ons
JSP - Java Server pages (Sun)
ASP - Active Server pages (Microsoft)
Flexibility of CGI, without performance overhead and I/O limitations
Better integration with vendor’s other web solutions
Some compatibility limitations

24. Sun’s Java Platform Java language: “write once run anywhere”
Assorted “editions”
ME (embedded)
SE (standard) - for desktop & workstation
EE (enterprise) - for multi-tier, robust, multiuser applications

25. Java 2 Platform (1999)

26. Microsoft .NET Platform
Integrated across servers, OS, applications, programming language environments
OLE - Object Linking and Embedding
Shared objects that provide specific functionality (e.g. sound clip)
[D]COM([Distributed] Component Object Model)
Connects client application and object (binary-compatible components)

27. MS OLE - DB

28. .NET Framework

29. Oracle’s Approach Aimed at distributed environments
N-tier architecture, based on industry standards
Designed for e-business
Components include:
TopLink (relate Java objects to relational databases)
Portal (entry point for web access)
Business Intelligence (Reports, Discoverer, etc)

30. Oracle Internet Platform