Chapter 1: Overview of Servlets and JavaSerevr Pages

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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.j
  ava 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 lt expression gt
• Scriptlets lt code gt inserted into _jspService
  method called by the service method
• Declaration lt! Code gt 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 lt! String strstr gt
• 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 lt_at_ page attrvaluegt
• 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