ServletsandJavaServerPages.ppt

Agenda Servlets Introduction Basics Advanced topics JavaServer Pages? (JSP) Introduction JSP Syntax Current Status and Roadmap Conclusions, QA What are Servlets? Java? objects which extend a HTTP server A Java Platform Standard Extension Alternative for CGI, NSAPI, ISAPI, etc. Multiple threads of execution Why Servlets? HTTP is a ubiquitous protocol on the web today Much less overhead than the CGI model Superior alternative to proprietary HTTP server APIs Protocol and Platform Independent Write Once, Serve Anywhere! Servlets vs. CGI Servlets vs. CGI Servlets are Lightweight Can run in the same process as host HTTP Server Are fully threadable Can be deployed into distributed server environments where RAS (Reliability, Availability, Scalability) are critical Easy to Develop It’s Java technology! Extensive availability of Java Platform libraries such as JDBC, RMI, EJB, JMS, JavaMail?, etc. Extensive third party libraries Can develop with the smallest of servlet engines on a laptop, deploy on the most mission critical servers on enterprise class hardware Easy to Maintain Most servers allow reloading of a servlet by administrative action Servlets can be remotely loaded allowing several servers to share code Possible Servlet Applications Site wide document management Electronic Commerce HR Applications Conference and chat applications Anything else you can put on the Web! Code for a Simple Servlet Servlets Usage Results of JavaWorld? Poll (December 1998) 600 respondents Top reasons for using servlets Platform Independence Power Performance Ease of use Database access Talk to applets Security Agenda Servlets Introduction Basics Advanced topics JavaServer Pages (JSP) Introduction JSP Syntax Current Status and Roadmap Conclusions, QA Servlet Basics Servlets have well defined lifecycle Servlets are managed objects that are loaded on demand and can be unloaded by the server at any time Servlets can be mapped to any part of the URL namespace that a servlet engine has control