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Chapter 1: Overview of Servlets and JavaSerevr Pages

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• What Are Servlets: Replacement for CGI• Basic operations: receive, process, send• Advantages over CGI and other

techniques:– Efficient– Convenient– Powerful– Portable– Secure– Inexpensive

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• What is JavaServer Pages (JSP): Enables you to mix static HTML with dynamically generated content.

• Advantages of JSP Versus:– ASP: Dynamic part is written in JAVA– PHP: Extensive library for Networking, DB,

distributed Objects– Pure Servlets: Easier to develop specially if the

pages are almost static ones.– SSI: More powerful set of tools– JavaScript: Access DB and networking– Static HTML: You know

• Installing s/w: Available In Windows machine Stright107.

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Chapter 2: First Servlets

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• Basic Servlet structure: ServletTemplate.java• Simple Servlet generating plain text:

HelloWorld.java• A Servlet that generates HTML:

HelloWWW.java (Always set Content type first)• Packaging Servlets: HelloWWW2.java• Simple HTML-Building Utilities:

ServletUtilities.java & HelloWWW3.java

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• The Servlet life cycle:– The init() method: With/Without parameters– The service() method: support HEAD, OPTIONS,

and TRACE requests. Call doGet, doPost, doXxx– Implementing the SingleThreadModel– The destroy() method: performs cleaning up

• Using Initialization Parameters: ShowMessage.java

• Using Modification Date: LotteryNumbers.java• Debugging Servlets: log, command windows,

stop/start, look and request/response data• Sending HTTP request: WebClient.java

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Chapter 3: Reading Form Data

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• Reading Form Data: methods getParameter(“name”), getParameterValues(“name”), getParameterNames()

• Example: ThreeParams.java and .html

• Using GET and POST: ShowParametersGetForm.htm, ShowParametersPostForm.htm, & ShowParameters.java

• A resume posting service: SubmitResume.htm & SubmitResume.java

• Filtering HTML specific characters: BadCodeServlet.java, FilteredCodeServlet.java

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Chapter 4: Handling HTTP Request Headers

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• The request object has a number of methods to enable you to access all the headers of an HTTP request

• getHeader(), getContentLength(), getContentType(), getHeadersName(), etc.

• Other methods such as getMethod(), getProtocol(), etc. can access info into the request line

• Example: ShowRequestHeaders.java

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• HTTP 1.1 request headers are case insensitive and include:– Accept (MIME type)– Accept-Encoding, Accept-Language, Accept-Charset– Authorization– Connection– Content-Length– Content-type– From (Email address of the sender- Only sent by

web Spiders)– Host, User-Agent, Via, ……etc

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• Sending compressed web pages: EncodedPage.java

• Restricting access to Web page: ProtectedPage.java and PasswordBuilder.java

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Chapter 5: Accessing the Standard CGI Variables

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• The standard CGI variables can be accessed using servlets but in many cases we really do not want to do so.

• Examples: CONTENT_LENGTH, DOCUMENT_ROOT, QUERY_STRING, ETC.

• Program example: ShowCGIVariables.java

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Chapter 6: Generating the Server Response: HTTP Status Codes

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• The status code is usually returned using response.setStatus(int code)

• There are two other methods sendError(int code, String message) & sendRedirect(String URL)

• Generally, there is five categories– 100-199: Informational– 200-299: Request success– 300-399: Files moved (usually indicates a location

header)– 400-499: Client error– 500-599: Server error

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• Example: Front end to various search engines• Files: SearchEngines.java, SearchSpec.java,

SearchEngines.html

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Chapter 7: Generating the Server Response: HTTP Response

Headers

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• Any permitted header can be set by using the method setHeader(String header name, String value);

• In Servlets 2.2 setHeader() replace existing ones so you can use addHeader() to add new entries of an already existed header

• Convenient methods setContentType(), setContentLength(), addCookie(), sendRedirect()

• Some common headers: Connection, Content-Language, Content-Type, Content-Length, Location, Refresh { response.setHeader(“Refresh”, “5”); }

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• Persistent Servlet and auto-reloading – Handling multiple simultaneous connections:– Maintaining state between requests or even among

various servlets in the same engine using the ServletContext object (getServletContext())

• Code: PrimeNumbers.java, PrimeList.java, Primes.java

• Persistent HTTP connections: PersistentConnection.java & ImageRetriever.java

• Generating Gif Images: ShadwedText.java & MessageImage.java

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Chapter 8: Handling Cookies

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• Steps: – Create a cookie: new Cookie(name. value)– Access attributes: cookie.setXxx(), cookie.getXxx()– Insert it into response header: addCookie(cookie)– Get all cookies: request.getCookies(), returns array

of cookies objects– Use getName() and getValue() methods of cookie

• Examples: setCookies.java & ShowCookies.java

• Customized search engine: CustomizedSearchEngine.java & SearchEngineFrontEnd.java

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Chapter 10: JSP Scripting Elements

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• A very attractive alternative to Servlets specially if the page is mostly static with few dynamic parts

• Advantages: Widely supported & using JAVA!!!• The JSP page is automatically converted to

normal Servlet!• Three types of JSP constructs

– Scripting elements: Java code that will become part of the resultant Servlet

– Directives: Control the overall Servlet structure– Actions: Specifying components that control JSP

engine

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• Scripting Elements: – Expressions: <%= expression %>– Scriptlets: <% code %> {inserted into _jspService

method called by the service method}– Declaration: <%! Code %> {code inserted outside

any existing method

• Expressions example: Expressions.jsp• Scriptlets: in many situations you need more

complex behavior than what simple expressions can do

• Example: BGColor.jsp

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• JSP Directives: Contain code that will be inserted in the main body of the resultant Servlet. Ex <%! String str=“str” %>

• They are normally used in conjunction with Expressions

• Example: AccessCounts.jsp • Predefines Variables: Simplify JSP code

– request: The request object!!– response: The response object!!– out: An object of type JSPWriter which is a child of

PrintWriter– application: The ServletContext object

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Chapter 11: JSP Page Directive

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• There are three types of directives:– page: import classes, select parent, set content type– include: Insert a file in the Servlet class during JSP

file translation– taglib: allow you to define custom markup tags

• The page directives has a number of case-sensitive attributes.

• General form: <%@ page attr=“value”%>• The “import” attribute, ex ImportAttribute.jsp• The “contentType” attribue: ex ContentType.jsp to

return text/plain. Ex, Excel.jsp to return Excel spread sheet using tabs & ApplesAndOranges.jsp using tables.

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• The “isThreadSafe” attribute: default is true otherwise specify false for the SingleThreadModel

• The “buffer” & “autoflush” attributes• The “errorPage” and “isErrorPage” attributes:

ex ComputeSpeed.jsp & SpeedError.jsp