Copyright © 2002 ProsoftTraining. All rights reserved. Java Servlets

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 1: Introduction to Java Servlets

Objectives Describe the differences between servlets and other Web application technologies Explain the difference between the GET and POST methods of making an HTTP request Create a simple servlet using GET Create a simple servlet using POST Define a simple deployment descriptor

Introduction to Web Applications Web application technologies –Common Gateway Interface (CGI) –Server extensions –Server-side scripting –JavaServer Pages –Java servlets

Hypertext Transfer Protocol The GET method The POST method Additional methods

Writing a Simple Servlet

Responding to Form Data FormServlet getParameter method Using the POST method

Deployment Descriptors XML files conforming to Sun Microsystems DTD –Describes servlets contained within a Web application

Summary Describe the differences between servlets and other Web application technologies Explain the difference between the GET and POST methods of making an HTTP request Create a simple servlet using GET Create a simple servlet using POST Define a simple deployment descriptor

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 2: The Servlet Life Cycle

Objectives Describe the servlet life cycle Create init and destroy methods Retrieve servlet initialization parameters Use the SingleThreadModel interface Retrieve CGI environment variables Retrieve and use the ServletContext object Use temporary files

The Multithreaded Model Servlets typically operate in a multithreaded environment –The Web server usually instantiates only one instance of a servlet to serve all clients Deployment descriptors and the multithreaded model

The Single Thread Model The Web server guarantees that no two threads will ever operate concurrently on the same servlet instance To designate servlets to use the single thread model, implement the following interface: –javax.servlet.SingleThreadModel

The init and destroy Methods The init method –Initialization parameters and the deployment descriptor The destroy method

CGI Environment Variables AUTH_TYPE CONTENT_LENGTH CONTENT_TYPE HTTP_ACCEPT HTTP_REFERER HTTP_USER_AGENT PATH_INFO PATH_TRANSLATED QUERY_STRING REMOTE_ADDR REMOTE_HOST REMOTE_USER REQUEST_METHOD SCRIPT_NAME SERVER_NAME SERVER_PROTOCOL SERVER_PORT

The ServletContext Methods for obtaining server information Using temporary files

Summary Describe the servlet life cycle Create init and destroy methods Retrieve servlet initialization parameters Use the SingleThreadModel interface Retrieve CGI environment variables Retrieve and use the ServletContext object Use temporary files

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 3: Responding to a Request

Objectives Use client-side caching Use client pull to update a client Redirect the client to another URL Use persistent connections Use response status codes Return a file to a client Dynamically generate images

Controlling the Client Using client-side caching Using client pull Redirecting the client

Persistent Connections public class PersistentConnection extends HttpServlet { public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setBufferSize(32 * 1024); resp.setContentType("text/html"); PrintWriter out = resp.getWriter(); // Generate a response }

Status Codes Status code constants sendError method used to set status code

Multimedia Content Returning a file Dynamically generating images

Summary Use client-side caching Use client pull to update a client Redirect the client to another URL Use persistent connections Use response status codes Return a file to a client Dynamically generate images

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 4: Servlet Sessions

Objectives Track a session using hidden form fields Track a session using URL rewriting Track a session using cookies

Hidden Form Fields Hidden form field named "SID" with an assigned value of " "

URL Rewriting Servlets can build URLS that add information in the form of additional path information

Cookies Small pieces of information transmitted from a Web server to a Web browser Represented in Java using the Cookie class

Summary Track a session using hidden form fields Track a session using URL rewriting Track a session using cookies

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 5: Authentication and Security

Objectives Authenticate a user using HTTP-based authentication Authenticate a user using a form Use Secure Sockets Layer to improve security

HTTP-Based Authentication Users The deployment descriptor Servlets and authentication

Form Authentication Requires modification of the deployment descriptor –The login-config element must be modified to indicate that form authentication is to be used and to provide the URL for a login page and login error page

Summary Authenticate a user using HTTP-based authentication Authenticate a user using a form Use Secure Sockets Layer to improve security

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 6: Inter-Servlet Communication

Objectives Share data with another servlet Handle a single request using multiple servlets

Sharing Data Data-sharing methods of the ServletContext interface Sharing data with another ServletContext

Dispatching to Another Servlet The forward method The include method

Summary Share data with another servlet Handle a single request using multiple servlets

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 7: Building Enterprise Web Applications

Objectives Use JNDI to look up EJBs, resource factories and environment entries Write servlets for use in a distributed environment Use JavaMail to send

Java Servlets and JNDI Referencing EJBs Referencing resource factories Referencing environment entries

Clustering and Java Servlets Clustering styles Developing distributable servlets

JavaMail Add-on API that creates a full-fledged POP/iMAP client –Session class –getDefaultInstance static method

Summary Use JNDI to look up EJBs, resource factories and environment entries Write servlets for use in a distributed environment Use JavaMail to send

Copyright © 2002 ProsoftTraining. All rights reserved. Lesson 8: Internationalization

Objectives Use the Unicode escape sequence to specify special Latin characters Use alternative character sets to generate a non-Latin character response

The Latin Character Set Non-English Latin characters Languages and language codes

Non-Latin Character Sets Arabic Chinese Japanese Korean Russian

Summary Use the Unicode escape sequence to specify special Latin characters Use alternative character sets to generate a non-Latin character response

Java Servlets Introduction to Java Servlets The Servlet Life Cycle Responding to a Request Servlet Sessions Authentication and Security Inter-Servlet Communication Building Enterprise Web Applications Internationalization