The topics listed below were deemed “important to know” for the Comp241 Midterm scheduled for Nov 13, 2008 by Rob Thorndyke.

Session Management

Those are the advantages/disadvantages.  How do you actually implement these?

Client

• Cookies
  • persistent
  • can be turned off / modified
• Query String (BAD, try not ever to use these if you want your site to rank in google)
  • can’t be turned off
  • user sees it, and curious people will change them
  • search engines can’t deal with them very well
  • browsers can limit the max length
  • setting values is not supported in .NET
  • GET only! does not work with POST
• View State (implemented using hidden fields)
  • nice support in .NET
  • supports POST
  • with ViewState, watch the bandwidth – everything gets sent back and forth
• Hidden Fields

For all of the above, data must be key/value pairs and must also be serializable.

Server

• Sessions
  • unique to each client “connection”
  • time out after a while
  • may depend on Cookies (the session id is generally stored in a cookie, this can be turned off but then the session id goes in the query string)
• Application
  • global – share data between clients
  • web servers can reset these at seemingly random moments

Data Management

Connected Objects

• DBCommand – SQL Statement
• DBConnection – interface to the DB
• DBDataReader
  • read-only
  • forward-only
  • safer
  • faster (lightweight)
• DBDataAdapter – read/write and bidirectional

Disconnected Objects

• DataSet
• DataTable
  • DataTable.Select() – returns DataRow[] (array of DataRow’s)
• DataRow
  • Field access (read overwrite)
  • Acts as dictionary

int status = (int) ds.Tables["table"].Select("row = 7")[0]["status"];

• DataColumn
• Relation

Data-Bound Controls

• Control.Databind() – Refreshes the view with current DataSource

Input Validation

General Info

• gives you a chance to check user input and make sure it is valid
• generally you need to do the validation on BOTH the server and the client
• server
  • needed in case client validation is bypassed
  • has access to DB -> more complex validation
• client
  • convenient – quick validation without PostBack

Validation Controls

• RequiredFieldValidator
  • non-empty / not “default”
• CompareValidator
  • compare two values (==, <=, >=, …etc)
• RangeValidator
  • MinimumValue
  • MaximumValue
  • it checks for value between (inclusive)
• RegularExpressionValidator
• CustomValidator
  • ClientFunctionName (javascript function)
  • ServerValidate event handler

C# Properties

private int age;
public int Age {
    get { return age; }
    set { age = value; }
}