Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Web Application Development Lec 25 Web Application Development we used J2SE until now For web application development, we need J2EE (Servlets API, JSP API, JSF API etc) Web Based Performance Review Management System Web Based School Management System What is a Web Application HTTP Communication Model A communications model • Client, often but not always a web browser, sends a request for a resource to a server. •The server returns a response or an error message. • Stateless • No immediate feedback • No details on how request is made HTTP Communication Model Different clients like •Web browsers •FTP clients (e.g., interarchy on MacOS X) •Software registration programs •telnet HTTP Communication Model Web Server? Software that provides services to access the Internet, or an intranet. A web server hosts web sites Provides support for HTTP and other protocols Executes server-side programs (such as CGI scripts or servlets) that perform certain functions. HTTP HTTP Basics HTTP is a request-response oriented protocol. Parts of an HTTP request Request Method URI Header Fields Body HTTP response contains Result Code Header Fields Body HTTP Request Example Request parameters etc Request Parameters Request can also contain additional info in the form of parameters In the URL itself as a query string http://www.gmail.com/register?name=ali&state=punjab As part of the request body Shown earlier in the diagram HTTP Response Example HTTP Response Codes Codes fall into five general categories 100-199 200-299 Values in the 300s are used for files that have moved and usually include a Location header indicating the new address. 400-499 Values in the 200s signify that the request was successful. 300-399 Codes in the 100s are informational, indicating that the client should respond with some other action. Values in the 400s indicate an error by the client. 500-599 Codes in the 500s signify an error by the server. Common HTTP Response Codes 200: means every thing is fine. 404: Indicates that the requested resource is not available 401: Indicates that the request requires HTTP authentication 403: Indicates that access to the requested resource has been denied 503: Indicates that the HTTP server is temporarily overloaded and unable to handle the request Server Side Programming Static Pages 1 - Request file 2 - Retrieve file 3 - Send file Example: Static Page Dynamic Pages 1 - Request service Do Computation Generate HTML page with results of computation Return dynamically generated HTML file Why build Pages Dynamically? The Web page is based on data submitted by the user The Web page is derived from data that changes frequently E.g. results page from search engines and order confirmation pages at on line stores E.g. a weather report or news headlines page The Web page uses information from databases or other serverside resources E.g. an e-commerce site could use a servlet to build a Web page that lists the current price and availability of each item that is for sale\ Course Registration System Course Registration System What is Server-Side Programming (SSP)? Technologies for developing web pages that include dynamic content. Can produce web pages that contain information that is connection- or time-dependent. Dynamic Web Content Technologies Evolution (only figure) CGI CGI (in C) (java, C++) Speed, Security Servlet (Java) Template (ASP, PHP,CFML) complexity JSP Web-Based Enterprise Applications in Java Figure shows a simplified view of one application and its layers. Java Web Application Technologies (Presentation/Web Tier)