2314 Programming Language Concepts

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2314 Programming Language Concepts

• Test 2 Grades
• Introduction to ASP.NET

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Test 2 Grades
Average 75.7 Pass Rate 60
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Grade Differential (Test 1 Test 2)
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Sample Answers

• Progression from Win32 API (system calls) to MFC
  (macros) to .NET (drag-drop/WYSISYG)
• Most of the time was spent in design
• Data structure (array of records) and appropriate
  methods/algorithms and interface
• GUI vs. console app (little change to core)
• Paint and onClick methods
• Details and specific information (not vague)

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Introduction to Client-Server Programming

• ASP.NET
• WebMatrix

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Client-Server Cycle

• Client requests page
• Client formats an HTTP request
• HTTP Example Server Side
• Server responds
• Finds requested file
• Formulates response and sends to client
• Header
• Fields (informs client)
• Body (content)

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ASP

• Implemented via asp.dll (ISAPI)
• Process ASP files before sending to client
• Uses VBScript or JavaScript
• Embed code data (BAD!)
• Mixes content with code
• Optionally include

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ASP (cont)

• Limits access to controls
• Ad Rotator
• FileSystemObject
• ADO (ActiveX Data Object) DB Connections
• Can purchase 3rd party components or develop COM
  wrappers to access Win32 API

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ASP.NET

• Implemented via ISAPI aspnet_isapi.dll
• Processes ASPX files before sending to client
• Uses the CLR (common language runtime)
• Can program ASP.NET in ANY CLR language (C
  VB.NET most popular)

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ASP.NET

• Full access to the .NET Class Library (immense!)
• Session information shared across multiple
  servers (server farm scalability)
• Configuration easy via .config files

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ASP.NET in C

• Two sides
• Code definition
• HTML aspSOMETHING object
• A simple calculator example

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The Form
Absolutely, positively NEVERforget the RunAt
attribute!

• ltHTMLgt
• ltBODYgt
• ltform RunAt"server"gt
• ltaspTextbox id"op1" RunAt"server"/gt
• ltaspTextBox id"op2" RunAt"server"/gt
• ltaspButton id"Sum" text""
  OnClick"DoAdd" RunAt"server"/gt
• ltaspLabel id"Result" RunAt"server"/gt
• lt/formgt
• lt/BODYgt
• lt/HTMLgt

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The Code

• ltSCRIPT Language"C" RunAt"server"gt
• void DoAdd (Object sender, EventArgs e)
• int i Convert.ToInt32(op1.Text)
• int j Convert.ToInt32(op2.Text)
• int r i j
• Result.Text r.ToString()
• lt/SCRIPTgt

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Two Options

• Place the HTML and SCRIPT in one file with an
  ASPX extension
• Place the HTML in a file with an ASPX extension
• Place the code in a file with a .cs extension
• Add a reference to the code file in the ASPX file
• lt_at_ Page language"c" src"SOURCE.cs" gt

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When an ASPX File is Requested

• Client sends a request to server for add.aspx
• Server locates file realizes its extension
• Sends it to the appropriate ISAPI processor
• Processes file, replacing references to asp
  object controls with HTML 4.01
• Only compiles file if it has changed since last
  referenced (JIT)
• Uses cache copy of file if possible (improves
  performance)
• Executes Load and Init functions (if any)
• Adds hidden state information
• Client only sees HTML, no source code at all
• Serves the result to client
• Client receives HTML and renders it in browser

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Client-Server Request/Response Process
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When an Event is Generated

• Callback to server
• Function is executed
• Possible changes to HTML
• Server responds with HTML 4.01 results
• Does require round-trip
• Usually efficient b/c of small data in transit

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Putting it Together (calc.aspx)

• ltHTMLgt
• ltBODYgt
• ltform RunAt"server"gt
• ltaspTextbox id"op1" RunAt"server"/gt
• ltaspTextBox id"op2" RunAt"server"/gt
• ltaspButton id"Sum" text""
  OnClick"DoAdd" RunAt"server"/gt
• ltaspLabel id"Result" RunAt"server"/gt
• lt/formgt
• lt/BODYgt
• ltSCRIPT Language"C" RunAt"server"gt
• void DoAdd (Object sender, EventArgs e)
• int i Convert.ToInt32(op1.Text)
• int j Convert.ToInt32(op2.Text)
• int r i j
• Result.Text r.ToString()
• lt/SCRIPTgt

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Two More Tasks

• Create a virtual directory in IIS pointing to the
  directory that contains calc.aspx
• Remember all dynamic pages MUST be viewed in a
  browser (you cant just double-click them in
  explorer)
• Allows you to view the page in your browser
• Run the permissions wizard on this new virtual
  directory
• Allows the ASP.NET page to be processed
• Get an error (cannot display page) if you
  forget this step

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Resultant Page (FINALLY)
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The HTML Source

• ltHTMLgt
• ltBODYgt
• ltform name"_ctl0" method"post"
  action"calc.aspx" id"_ctl0"gt
• ltinput type"hidden" name"__VIEWSTATE"value"dDwt
  MTM3MDk5MDcwNDs7PvmsttsAST3BC5jicR6AndD0Ow" /gt
• ltinput name"op1" type"text" id"op1" /gt
• ltinput name"op2" type"text" id"op2" /gt
• ltinput type"submit" name"Sum" value""
  id"Sum" /gt
• ltspan id"Result"gtlt/spangt
• lt/formgt
• lt/BODYgt
• lt/HTMLgt

Auto-generated material is highlighted
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Resultant Page (after submit)
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The HTML Source (after submit)

• ltHTMLgt
• ltBODYgt
• ltform name"_ctl0" method"post"
  action"calc.aspx" id"_ctl0"gt
• ltinput type"hidden" name"__VIEWSTATE"
  value"dDwtMTM3MDk5MDcwNDt0PDtsPGk8MT47PjtsPHQ8O2w
  8aTw3PjsO2w8dDxwPHA8bDxUZXh0Oz47bDwxMjsPjsOzsO
  z4Oz4Oz6pyFGIUcsfxJmwPKg9fE2//Jx4Q" /gt
• ltinput name"op1" type"text" value"5"
  id"op1" /gt
• ltinput name"op2" type"text" value"7"
  id"op2" /gt
• ltinput type"submit" name"Sum" value""
  id"Sum" /gt
• ltspan id"Result"gt12lt/spangt
• lt/formgt
• lt/BODYgt
• lt/HTMLgt

Modified material is highlighted