Components of a TP Application?
Front-end program; request controller; transaction server; dbms
What are the functions of the FRONT-END PROGRAM?
TO gather input and display output (user interaction) and to construct requests and interpret replies
Core technologies for client side:
JAVA APPLETS, JAVASCRIPT
core technologies for server-side:
CGI programs, web server API, java servlets, SSI, jsp
applet advantages
- enhance UI-Support
- Applet may connect directly to Db-server, connection-server and application server
- applet state can preserve db-connections across interactions allowing long, multi-step transactions and distributed transactions
Applet disadvantages:
- higher initial loading time due to downloading the applet from web-server
- java security (unsigned applet can only connect back to server of origin)
- No adequate support for combined client/server-side transactions
- requires enabling/allowing connection to db-server systems from web clients
ajax characteristics
Ajax avoids reloading complete pages, only interacts with server for subset of the content or avoids interations altogether. The user perceives web application as faster, due to asynchronous loading of data. State preserved inside javascript variables across multiple interactions
statefull interactions may depend on the outcome of previous steps. HTTP is a stateless protocol
session support is required. Name alternatives
Common techniques: HTTP-cookies, http-authentication, URL encoding, Form variables (hidden form fields),
