1. Session 1 Web Applications An Overview

2. JSP and Servlets / Session 1 / 2 of 15 Objectives Describe a multi-level architectural view of a Web application. Review HTTP protocol Describe the anatomy of a typical Web Application. Describe the Web development process Setup Tomcat environment in Java Studio Enterprise 8. 3. JSP and Servlets / Session 1 / 3 of 15 Desktop Applications 2-1 User Windows Media Player User selects an mp3 file Media Player playing the mp3 file 4. JSP and Servlets / Session 1 / 4 of 15 Desktop Applications 2-2 User Windows Media Player Request = Select a file to play User sends a request Player sends a response Response = Media Player plays the selected file Media Player is an example of desktop application 5. JSP and Servlets / Session 1 / 5 of 15 Web Applications 2-1 Web Site hosted on a Web Server www.mp3.com 6. JSP and Servlets / Session 1 / 6 of 15 Web Applications 2-2 www.mp3.com Web Application Web Application running on a Web Server User requests a song Song is played in response Advantages of Web Applications: Accessing Web Applications is easier Maintenance and deployment costs are low 7. JSP and Servlets / Session 1 / 7 of 15 HTTP Protocol 3-1 Get File HTTP GET image/bar01.jpg HTTP/1.1 HTTP/1.1 200 OKFile Received HyperText Transfer Protocol Stateless protocol Used to send request and response messages over the Internet. Uses port 80 to send and receive messages 8. JSP and Servlets / Session 1 / 8 of 15 HTTP messages consist of: Request Response Headers HTTP Protocol 3-2 Request Message Request Line Header Information Method Resource Name Version GET/POST bar01.jpg HTTP/1.1 Browser Type Content Type User-Agent: Mozilla/4.0 (Compatible; MSIE 4.0 : Windows 95 Accept: image/gif, image/jpeg, text/*, */* Response Message Status Line Header Information Version Status Code Description HTTP/1.1 200 OK Server Software Modified Date Size (bytes) Content Type Server: JavaWebServer Last modified: Tuesday, 07-Sep-04 1:14:34 GMT Content-length: 100 Content-type: text/plain 9. JSP and Servlets / Session 1 / 9 of 15 HTTP Protocol 3-3 HTTP protocol uses the following methods to send request messages: GET Method POST Method GET Method Used for retrieving information such as document, charts, or database query results. Requested pages can be bookmarked and emailed. Request information is sent as query string POST Method Used to send sensitive information such as credit card numbers or information to be saved in the database. Requested pages cannot be bookmarked or emailed. No size limit on information being sent query string (240-255 characters) 10. JSP and Servlets / Session 1 / 10 of 15 Application Architecture Software Application Components -Presentation Logic -Application Logic -Data Access Logic Types of Architecture -One-Tier -Two-Tier -Three-Tier Data Access Business Presentation Data Access Business Presentation 11. JSP and Servlets / Session 1 / 11 of 15 Web Application Architecture Web Applications use Three-tier architecture Presentation Tier Clients Business Tier Web Server Database Data Tier 12. JSP and Servlets / Session 1 / 12 of 15 Web Application Directory Structure Web Application HTML files Images Servlets JSP pages JavaBeans Jar files Applets Tag files Tag Library Descriptor files Deployment descriptors .war file Document Root Static Files(html, images, JSP) WEB-INF lib tags .tld, web.xmlclasses Web Application Directory Structure index.html, login.jsp, contactus.jsp ViewBooks.jsp, logo.jpg book1.jpg AddBook.class, DeleteBook.class mbase.jar, msqlserver. jar, msutil.jar DisplayBook.tag web.xml, books.tld 13. JSP and Servlets / Session 1 / 13 of 15 Web Application Development Process Design a directory structure Write web application code Write deployment descriptor Compile the code Package web application Deploy web application Execute web application 14. JSP and Servlets / Session 1 / 14 of 15 Tomcat Configuration Demonstration Steps to configure Tomcat in Java Studio Enterprise 8 Select ToolsServer Manager 15. JSP and Servlets / Session 1 / 15 of 15 Summary Web applications are easy to maintain, upgrade and deploy as compared to desktop applications. Pages requested using GET method can be bookmarked and emailed. POST method is used when sending sensitive information such as credit card numbers, passwords and so on. In three-tier architecture, the presentation tier cannot interact with the data tier. JBuilder Enterprise 2005 can be configured to use external Tomcat installation.