1. Servlet V.B.Sanghavi

2. Overview of Servlet to create web application resides at server side and generates dynamic web page V.B.Sanghavi

4. What is a Servlet? Technology – to create web application API -- many interfaces and classes. interface -- implemented for creating any servlet. class-- extend the capabilities of the servers and respond to the incoming request web component -- deployed on the server to create dynamic web page. V.B.Sanghavi

5. CGI(Commmon Gateway Interface) V.B.Sanghavi

6. Disadvantage of CGI If number of clients increases, it takes more time for sending response. For each request, it starts a process and Web server is limited to start processes. It uses platform dependent language e.g. C, C++, perl. V.B.Sanghavi

7. Servlet Model V.B.Sanghavi

8. Advantages of Servlet The web container creates threads for handling the multiple requests to the servlet. better performance: because it creates a thread for each request not process. Portable and secure: because it uses java language. Robust: Servlets are managed by JVM so no need to worry about memory management, garbage collection etc. V.B.Sanghavi

9. Servlet Terminology V.B.Sanghavi

10. (1) HTTP Allows web servers and browsers to exchange data over the web. It is a request response and application-level protocol. Http uses reliable TCP connections by default on TCP port 80. It is stateless server doesn't recognize the user bydefault. V.B.Sanghavi

11. (2) Http Request Methods GET POST HEAD PUT DELETE OPTIONS TRACE Method Structure V.B.Sanghavi

13. (3) Web Container and Web Server It provides runtime environment for JavaEE (j2ee) applications. Responsible for initializing, invoking and managing the lifecycle of Servlet and JSP. Web Server is a running program or software that provides service. V.B.Sanghavi

14. (4) Deployment Descriptors Manage the configuration of web application. web.xml USE: 1.Initialize the parameters for servlets and web applications. 2.Servlet/JSP Definitions 3.Servlet/JSP mappings 4.Session Config 5.welcome-page, error-pages V.B.Sanghavi

15. (5) Content-type text/html application/msword application/jar application/pdf application/x-zip images/jpeg V.B.Sanghavi

16. Servlet public void init(ServletConfig config) public void service(ServletRequest request,ServletResponse response) public void destroy() public ServletConfig getServletConfig() public String getServletInfo() V.B.Sanghavi

17. Generic Servlet implements Servlet, ServletConfig and Serializable interfaces previous mathods public ServletContext getServletContext() public String getInitParameter(String name) public Enumeration getInitParameterNames() public String getServletName() public void log(String msg) V.B.Sanghavi

18. Http Servlet extends the GenericServlet class and implements Serializable interface previous methods protected void doGet(HttpServletRequest req, HttpServletResponse res) protected void doPost(HttpServletRequest req, HttpServletResponse res) V.B.Sanghavi

19. Program There are three ways to create the servlet. By implementing the Servlet interface By inheriting the GenericServlet class By inheriting the HttpServlet class V.B.Sanghavi

20. Servlet Config and Sevlet Context V.B.Sanghavi

21. Config public interface ServletConfig -implemented by the servlet container to initialize a single servlet using init() -initialization parameters are set to the servlet using the web.xml V.B.Sanghavi

22. Example Hello Topic Advance JAVA V.B.Sanghavi

23. Advantage you don't need to edit the servlet file. it is easier to manage the web application if any specific content is modified from time to time. V.B.Sanghavi

24. How to get the object of ServletConfig public ServletConfig getServletConfig(); Ex: ServletConfig config=getServletConfig(); V.B.Sanghavi

25. Methods public String getInitParameter(String name) public Enumeration getInitParameterNames() public String getServletName() public ServletContext getServletContext() public ServletConfig getServletConfig() V.B.Sanghavi

26. Example For one parameter : String s1=getServletConfig.getInitParameter (“topic"); V.B.Sanghavi

27. Context public interface ServletContext implemented by the servlet container for all servlet to communicate with its servlet engine like an application global variable mechanism for a single web application The ServletContext object is contained within the ServletConfig object. V.B.Sanghavi

28. Topic Advance JAVA V.B.Sanghavi

29. Advantage Easy to maintain if any information is shared to all the servlet. we don't need to modify the servlet. V.B.Sanghavi

30. Usage to get configuration information from the web.xml file to set, get or remove attribute from the web.xml file provide inter-application communication V.B.Sanghavi

31. ServletContext Method public void setAttribute(String name,Object object) public Object getAttribute(String name) public void removeAttribute(String name) V.B.Sanghavi

32. How to get the object of ServletContext interface public ServletContext getServletContext() EX: ServletContext s = config.getServletContext(); ServletContext s=getServletContext(); String s1=getServletContext.getInitParameter (“topic"); V.B.Sanghavi

33. HttpServletRequest and HttpServletResponse interface V.B.Sanghavi

34. HttpServletRequest GET and POST method Servlet container recognizes request and passes to particular method. To encapsulate all Http-based Req. info., including headers and req.methods. V.B.Sanghavi

35. It includes : Role of Form data Form data and parameters Headers V.B.Sanghavi

36. Role of Form data http://commerce.rediff.com/commerce/v2/dis playbag.jsp?carttype=books http://commerce.rediff.com/commerce/v2/dis playbag.jsp?carttype=books Carttype=books -------  Form data V.B.Sanghavi

37. Form data and parameters public String getParameter(String name) public String[] getParameterValues(String name) public Enumeration getParameterNames() V.B.Sanghavi

38. Http Header Client -  send info. Regarding which software is being used, what file types the browser is capable of receiving etc. -getHeader(String name) -getHeaders(String name) -getHeaderNames() EX: Accept, Accept-Language, Host, User- Agent, Connection, etc. V.B.Sanghavi

39. HttpServletResponse Set Http Response header, set content –type or redirect Http requests to another URL. 1) setHeader( String name, String value) 2) getWriter () or getOutputStream() to write the content. 3) setContentType(String name) 4) sendRedirect (Stirng url) V.B.Sanghavi

40. sendRedirect() and Request Dispatcher Request Dispatcher only when the other servlet to which the request is being forwarded lies in the same application. Send Redirect can be used in both the cases if the two servlets resides in a same application or in different applications. V.B.Sanghavi

41. sendRedirect() response.sendRedirect("http://www. google.com"); V.B.Sanghavi

42. Request Dispatcher RequestDispatcher rd=req.getRequestDi spatcher("servlet2"); rd.forward(request, response); //method may be include or forward V.B.Sanghavi

43. RequestDispatcher Methods: public void forward(ServletRequest request,ServletResponse response)throws ServletException, IOException public void include(ServletRequest request,ServletResponse response)throws ServletException, IOException V.B.Sanghavi

46. Example V.B.Sanghavi

47. Session Handling V.B.Sanghavi

48. Session Collection of HTTP requests shared between a client and web server over a period of time. Set the lifetime of a session. Stateless protocol :HTTP V.B.Sanghavi

49. Session Tracking Techniques Cookies Hidden Form Field URL Rewriting HttpSession V.B.Sanghavi

50. Cookie small piece of information that is persisted between the multiple client requests. a name, a single value, and optional attributes such as a comment, path,a maximum age, and a version number V.B.Sanghavi

51. HTTP Header HTTP/1.1 200 OK Date: Fri, 04 Feb 2000 21:03:38 GMT Server: Apache/1.3.9 (UNIX) PHP/4.0b3 Set-Cookie: name=xyz; expires=Friday, 04-Feb- 07 22:03:38 GMT; path=/; domain=tutorialspoint.com Connection: close Content-Type: text/html V.B.Sanghavi

52. How Cookie Works? public void addCookie(Cookie ck) public Cookie[] getCookies(): V.B.Sanghavi

53. Constructor and Methods Cookie() Cookie(String name, String value) public void setName(String name) public void setValue(String value) public void setMaxAge(int expiry) public String getName() public String getValue() V.B.Sanghavi

54. Create Cookie Cookie ck=new Cookie("user",“abc"); response.addCookie(ck); //adding cookie in the response V.B.Sanghavi

55. Get Cookies Cookie ck[]=request.getCookies(); for(int i=0;i<ck.length;i++) { out.print(" "+ck[i].getName()+" "+ck[i].get Value()); } V.B.Sanghavi

56. Servlet Cookie Program V.B.Sanghavi

57. URL Rewriting we append a token or identifier to the URL of the next Servlet or the next resource. It will work only with links. url ? name1=value1 & name2=value2 V.B.Sanghavi

59. Ex: out.print(" vi sit "); V.B.Sanghavi

60. HttpSession interface container creates a session id for each user. The container uses this id to identify the particular user V.B.Sanghavi

62. Methods public HttpSession getSession() public HttpSession getSession(boolean create) public String getId() public long getCreationTime() public long getLastAccessedTime() public void invalidate() V.B.Sanghavi

63. Ex: In first servlet---  HttpSession session=request.getSession(); session.setAttribute("uname",n); In second servlet---  HttpSession session=request.getSession(); String n=(String)session.getAttribute("uname"); V.B.Sanghavi

64. Hidden Form Field hidden (invisible) textfield is used for maintaining the state of an user Better---need not to depend on browser.(maintained at server) V.B.Sanghavi

66. out.print(" "); V.B.Sanghavi

67. ServletFilter object that is invoked at the preprocessing and postprocessing of a request. to perform filtering tasks such as conversion, logging, compression, encryption and decryption, input validation etc. servlet filter is pluggable ---> less maintenance V.B.Sanghavi

69. Filter API Filter FilterChain FilterConfig V.B.Sanghavi

70. 1) Filter interface 1)public void init(FilterConfig config) 2) public void doFilter(HttpServletRequest request,HttpServletResponse response, FilterChain chain) 3) public void destroy() V.B.Sanghavi

71. doFilter method Examining the request Carrying out i/p filtering by wrapping the req. object Carrying out o/p filtering by wrapping the res. Object Invoking the next filter in the filter chain by calling chain.doFilter() or forwarding. V.B.Sanghavi

72. 2) Filter Config public String getFilterName() public String getInitParameter(String name) public Enumeration getInitParameterNames() public ServletContext getServletContext() V.B.Sanghavi

73. 3) Filter Chain responsible to invoke the next filter or resource in the chain. public void doFilter(HttpServletRequest request, HttpServletResponse response) V.B.Sanghavi

74. How to define a filter?......... //servlet-name V.B.Sanghavi

75. public class SimpleServletFilter implements Filter { public void init(FilterConfig c) throws ServletException { } public void doFilter(ServletRequest request, ServletResponse response, FilterChain fobj) throws IOException, ServletException { } public void destroy() { } } V.B.Sanghavi

76. THANK YOU V.B.Sanghavi