Indy Java User

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Indy Java Users Group
March 27, 2001 Sallie Mae 600p.m
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Mission Statement
Promote the use of the Java language and
components across all levels of interest in the
greater Indianapolis area, by serving as a
resource for knowledge, experience and career
opportunities.
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Agenda

• Pizza Welcome!! 600-615
• Announcements 615-630
• Joe Caron 630-730
• Quality Tip 730-745
• Performance Tip 745-800

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Announcements

• Next Meeting - April 24, 2002
• Mike Burba Sun ONE
• Java Jam - Kurt Kirkham
• Feedback Results
• eGroups.yahoo.com
• http//groups.yahoo.com/group/indyJug
• http//groups.yahoo.com/group/indyjug_opensource
• BOT Contest Deadline March 31
• http//developer.digi-net.com

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Announcements

• CRN Annual Survey
• 1) Call 1-800-939-6206
• 2) Ask for Amy Johnson
• 3) Request your gift
• Sweatshirt
• Cap
• T-Shirt
• Visit www.metafacts.com
• Visit www.crn.com

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Presentation Lineup

• Mark Steenbarger
• Indy Jug
• Joe Caron
• KingArthurFlour.com
• Mike Slattery
• SearchSoft.net
• Frank Morton
• Base2Inc.com

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JDBC Servlets/JSP

• Joe Caron
• Indianapolis Java Users Group
• March 27, 2002

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Database access through the web

• Sample application overview
• JDBC Fundamentals
• Servlet/JSP Fundamentals
• Implementation sample code
• Pitfalls, Surprises, Work-arounds

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Sample Application

• Message Board
• Membership Based
• Pass membership info to catalogue site for quick
  check-out
• Accumulate bakers points redeemable against
  online orders
• Member recipe box

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Sample Application

• JSP for presentation
• Servlets other java for app logic
• MySQL as the RDBMS
• Tomcat as Servlet/JSP container
• Linux (Red Hat 6.2)

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Sample Application

• www.bakingcircle.com
• Staging Server
• Entity Relationship Diagram
• Application Diagram
• Presentation Diagram

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JDBC Fundamentals

• Standard means of accessing any RDBMS for which
  there is a JDBC driver
• Drivers which implement Suns JDBC standard
  capture a DB connection as Java Object
• Change DBMS without changing any application code
  (except driver)
• Sun JDBC API overview

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JDBC Fundamentals

• Key objects
• Connection
• Statement
• PreparedStatement
• ResultSet / Rowset
• ResultSet MetaData
• DB MetaData

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JDBC Fundamentals

• Sun JDBC overview
• Basic Example - MySQL
• Basic Example - ORACLE
• Statement vs. PreparedStatement
• Stand-Alone Example
• API Documentation
• JDBC Optional DataSource

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Servlet/JSP Fundamentals

• Servlet Container (Tomcat, for example),
  working in conjunction with Web server (Apache or
  IIS)
• Integrated in J2EE compliant server (BEA,
  Iplanet, Orion)
• Many options regarding both the products and how
  to set them up

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Servlet/JSP FundamentalsCommon Set-Up
Redirect based on conf file
Web Server

• Servlet
• Engine

.html others
.jsp /servlet/
Client
Common directory structure
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Servlet/JSP Fundamentals

• Servlets like any other Java class, except
• Must extend HttpServlet
• Must contain a doPost or doGet method
• Come equipped to handle the laborious points of
  http
• Http requests and responses are made into Java
  objects
• Best alternative to traditional CGI

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Servlet/JSP Fundamentals

• Anatomy of a Servlet
• Optional init method, executes the first time a
  servlet is invoked
• doGet/doPost methods execute when request is made
• method signature accepts http request and
  response as parameters
• Optional destroy method
• www.servlets.com Samples

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Servlet/JSP Fundamentals

• One instance of Servlet for each Servlet name
• Same instance serves all requests to that name
• Instance members persist across all requests to
  that name.
• Local /block variables in doPost doGet are
  unique to each request

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Servlet/JSP Fundamentals

• Instance members vs local variables
• Major request and response methods
• More major request and response methods
• Making use of servlet context
• Keeping sessions the bane of all Web programming

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JSPs Servlets in disguise...

• Better alternative for presentation.
• Insert special brackets into HTML page to mark
  off Java code.
• A JSP is compiled into a Servlet the first time
  it is called.
• Crash course in JSP syntax

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JSP as presentation model
Servlet Performs the hard work
Helper objects Persistent bean objects DB
Connections, etc
App logic
Simple calls to bean properties
Client request
JSP Successful results
JSP Unsuccessful results
Subsequent client request
Presentation
No servlet need if bean still set
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JSP alternatives

• JSP can still result in unwieldy code creeping
  into HTML
• Most HTML editors dont like it
• JSPTaglibs and other templating programs may
  help.
• Much depends on how HTML documents are produced
  and what business logic you are presenting

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In Depth Examples

• Encapsulation of SQL calls
• List results and view thread detail
• Post reply and add to favorites
• Set all bean properties w/ request
• Edit users
• Query central

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Pitfalls, surprises, and work-arounds

• HTTP works via requests and responses. Client
  caching of responses poses a problem.
• Guard against evil use of the back button
• Dont assume everyones client will respond
  properly to the defaults
• Guard against easy spoofs of any GET request
  which alters data.

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