SOEN 343 Software Design

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SOEN 343Software Design

• Section H Fall 2006
• Dr Greg Butler
• http//www.cs.concordia.ca/gregb/home/soen343h-f0
  6.html

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Outline

• Data Gateways
• GetByLastNameEA
• Enterprise Applications
• SoenEA framework and samples.
• Controller patterns
• Focus Page Controller

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Enterprise Application Patterns
Template View
Page Controller
Presentation
Front Controller
Transform View
Domain Model
Transaction Script
Domain
Active Record
Row Data Gateway
Data Mapper
Data Source
Table Data Gateway
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Data Source Patterns
Template View
Page Controller
Presentation
Front Controller
Transform View
Domain Model
Transaction Script
Domain
Active Record
Row Data Gateway
Data Mapper
Data Source
Table Data Gateway
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Row Data Gateway

• An object that acts as a single record in the
  data source
• There is one instance per row
• Fowler RDG combines two roles
• Class Finder with find(id)Gateway method
• which returns the object
• Class Gateway which is the object
• Our PersGradeRDG (next slide) combines

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Row Data Gateway
PersGradeRDG
- name String - grade int
PersGradeRDG(name, grade) find(name)
PersGradeRDG insert() void update()
void delete() void getters and setters
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Row Data Gateway Find Code
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Row Data Gateway

• Code sample for Fowlers PersonRDG
• Note find method is static
• it is class method

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GetByLastName Example

• Simple web application to
• Input a students last name
• Fetch database record
• Output students full name

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GetByLastName

• Will look at
• Row Data Gateway
• PageController
• Transaction Script

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Row Data Gateway

• StudInfoRDG
• Represents record in DB of student
• StudInfoFinder
• Finds student record based on lastName
• Returns the StudInfoRDG
• Locates DB using DBRegistry

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Outline

• Enterprise Applications
• SoenEA framework and samples
• Simple sample GetByLastName
• Builds on HelloWeb

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Package structure
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Enterprise Application Patterns
Template View
Page Controller
Presentation
Front Controller
Transform View
Domain Model
Transaction Script
Domain
Active Record
Row Data Gateway
Data Mapper
Data Source
Table Data Gateway
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Transaction Script

• Fowler A TS organizes the business logic
  primarily as a single procedure where each
  procedure handles a single request from the
  presentation.
• The TS may make calls directly to the DB or
  through a thin DB wrapper.
• Think of a script fora use case or business
  transaction.
• Implementation can be
• shared among subroutines.
• Subroutines can be used by more than one script

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Transaction Script

• is essentially a procedure that takes the
• input from the presentation,
• processes it with validations and calculations,
• stores data in the database,
• (invokes any operations from other systems, and)
• replies with more data to the presentation
  perhaps doing more calculation to help organize
  and format the reply data.
• (Fowler)

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GetByLastName

• Will look at
• Row Data Gateway
• PageController
• Transaction Script

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Do-it-all Transaction Script

• A TS that does all the work itself
• Without a Finder
• Without a RDG
• Directly calls DB

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Do-it-all Servlet or Script, Class

• public class DoItAll extends javax.servlet.http.Ht
  tpServlet
• protected void doGet(
• HttpServletRequest request,
• HttpServletResponse response)
• throws ... //

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Do-it-all Transaction Script, doGet()

• String lastName request.getParameter(")
• Connection dbc DbRegistry.getDbConnection()
• String findSql "SELECT from where LastName
  ?
• PreparedStatement dbQuery dbc.prepareStatement(f
  indSql)
• dbQuery.setString(1, lastName)
• ResultSet rs dbQuery.executeQuery()
• rs.next()
• String firstName rs.getString("FirstName")
• lastName lastName.toUpperCase()
• PrintWriter out response.getWriter()
• response.setContentType("text/html")
• out.println("lth1gtHello "firstName"
  "lastName"lt/h1gt")

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Outline

• Controller patterns
• Focus Page Controller

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Controller Patterns
Template View
Page Controller
Presentation
Front Controller
Transform View
Domain Model
Transaction Script
Domain
Active Record
Row Data Gateway
Data Mapper
Data Source
Table Data Gateway
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Page Controller

• Fowler
• A Page Controller is an object that handles a
  request for a specific page or action on a web
  site.
• There is one input controller for each logical
  page of the web site.
• Page Controller
• handles the http get and post
• Decides which model and view to use

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Page Controller

• Responsibilities
• Decode the URL, extract any form data, decide
  action
• Create and invoke any model objects
• All relevant data from the html request should be
  passed to the model, so the model does not need
  any connection to html request
• Determine which view should display the result
  page
• Forward model information to it
• Helper objects can be created/used to perform
  tasks that are shared

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Page Controller

• Fowler Example
• display info about a recording artist
• ActionServlet implements common forward task
• ArtistController implements doGet()
• Checks artist name is ok
• Creates a new ArtistHelper object with Artist as
  attribute
• Adds helper information to html request
• Forwards request to Artist.jsp
• Artist.jsp is a TemplateView which gets
  information to display from helper object (which
  it gets from request)

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Page Controller
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GetByLastName

• Will look at
• Row Data Gateway
• PageController
• Transaction Script

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Page Controller

• SOEN EA sample
• display info about a student
• PageController implements doGet()
• Delegates to transaction script
• Note
• does not follow Fowlers use of .jsp
• delegates rather than forwards
• no explicit helper object
• (really StudInfoRDG is helper)