Wednesday, June 01, 2011

Notes ASP.Net


ASP.Net Configuration
Connecting Events
HTML Control Class
Web / Server Control Class
ASP postback - eg like AJAX
Dispose, Finalize, Finally, Close
ADO.Net - Accessing Data the Easy Way
ADO.Net - Example
ADO.Net - command parameters
ADO.Net - Data Binding
ADO.Net - Data Binding - DataList
ADO.Net - Styles and Templates summary
Windows Service Applications
VS Setup Projects
Understanding ADO.Net - from AppDev video tutorial
Using MySQL in Visual Studio
Configuring MySQL with ASP.Net
DataGrid - Sorting
GridView - Sorting
GridView - Selecting Rows, Clickable Rows
WebService in ASP.Net
ASP.Net Custom Control
How to Add Google Maps to your ASP.Net page
ASP.Net inline Tags <%...%>
ASP.Net calling Javascript client side

1. Visual Studio 2005 -> Help -> Contents -> .Net Development
-> Web Applications -> ASP.Net Quickstart Tutorials

System.Web.UI - Generic Page Class
custom page class (my *.cs file, eg HelloClass.cs)
custom aspx file (my *.aspx file, eg Hello.aspx)
Page object

class GlobalApp (global.cs)
global.asax -> contain event handling code, each application can
have one global.asax.

The classes are linked together like this:
VS2005: Global.asax no longer created automatically but can be added by:
Add new item -> Global Application Class.
Also the code behind global.asax.cs is no longer created, instead put
the code inline in global.asax
<%@ Page Language="CS" Inherits="HelloClass" Src="HelloClass.cs" %> -
if source is supplied
<%@ Page Language="CS" Inherits="HelloClass" %> - if dll is supplied
<form id="Form" runat="server">
<asp:Label id="lblTest" runat="server" />
public class HelloClass : System.Web.UI.Page {
protected System.Web.UI.WebControls.Label lblTest;
private void Page_Load(){
lblTest.Text = "Hello World";
some basic event available to global.asax inherited from HttpApplication:
ASP.Net Configuration
1. machine.config - one per server, located at:
2. web.config - one per application, as well as one in each virtual
3. Structure and contents of web.config
<?xml version="1.0" encoding="utf-8" ?>
<!-- custome settings - using your own keyword -->
<add key="ConnectionString" value="Data Source=localhost;Initial
Catalog=Pubs;User ID=sa"/>
<add key="SelectSales" value="Select * FROM Sales"/>
<httpRuntime />
<pages />
<compilation />
<customErrors />
<authentication />
<authorization />
<identity />
<trace />
<sessionState />
<httpHandlers />
<httpModules />
<globalization />
4. To make use of the special custom settings, eg.
using System;
using System.Configuration;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Project
public partial class ShowCustomConfigSettings : System.Web.UI.Page
protected Label lblTest;
protected void Page_Load(object sender, EventArgs e)
lblTest.Text = "This app will connect with the connection
string <br><br>";
lblTest.Text +=
lblTest.Text += "<br><br> and will execute the SQL statement <br>";
lblTest.Text += ConfigurationSettings.AppSettings["SelectSales"];

Connecting Events
case: A button called id="Convert" on the aspx page. Functionality is
in the function called
On the aspx page, have the attribute in the <%@Page .... >
To connect the function "Convert_ServerClick" to the event:
1. protected override void OnInit(EventArgs e) {
2. private void InitializeComponent() {
Convert.ServerClick += new EventHandler(Convert_ServerClick);
Note that EventHandler is a DELEGATE that connects a the function
The EventHandler delegate would have the same prototype of the
function it points to, ie.:
protected void Convert_ServerClick(Object sender, EventArgs e)
The ServerClick would be a type of the EventHandler delegate; perhaps
public event EventHandler ServerClick
perhaps defined under the Convert's class - HtmlInputButton
HTML Control Class
HtmlControl ---> System.Web.UI.HtmlControls namespace
Web / Server Control Class
Repeater ---> System.Web.UI.WebControls
BaseDataList (abstract)
ListControl (abstract)
BaseValidator (abstract)
ASP postback - eg like AJAX
1. Web control events that can use POSTBACK, when AutoPostBack property is set
to true:
Events Web Control
======= ===========================
Click Button, ImageButton
TextChange TextBox
CheckChanged CheckBox, RadioButton
SelectedIndexChange DropDownList, ListBox, CheckBoxList, RadioButtonList
2. ASP.Net automatically adds these to the HTML page:
<input type="hidden" name="__EVENTTARGET" value=""/>
<input type="hidden" name="__EVENTARGUMENT" value=""/>
<script language="javascript">
function __doPostBack(eventTarget, eventArgument){
var theform = document.Form1;
theform.__EVENTTARGET.value = eventTarget;
theform.__EVENTARGUMENT.value = eventArgument;
3. Add event handlers to the InitializeComponent() method
i.e. <button>.<Event> += new EventHandler(<functionName>)
eg txt.TextChanged += new EventHandler(CtrlChanged)
4. Implement using the added function:
private void CtrlChanged(Object sender, EventArgs e) { }
ADO.Net - Accessing Data the Easy Way
To retrieve information
1. Create Connection, Command and DataReader objects
2. Use DataReader to retrieve info and display it on web
3. Close connection.
4. Send page to user.
To add or update information
1. Create new Connection and Command objects.
2. Execute the Command
ADO.Net - Example
using System.Data;
using System.Data.SqlClient; // for MS SQL
using System.Data.OleDb; // for general connector
// Define the connection to Database
<x>={Sql, OleDb, ...}
<x>Connection myConn = new <x>Connection();
myConn.ConnectionString = "Provider=SQLOLEDB.1; Data
Source=localhost;" + " Initial Catalog=Pubs; User ID=root";
// the provider is need when <x>=OleDb, but not when <x>=Sql.
// Password is not passed here if using "Integrated Windows Authentication"
myConn.ConnectionString = "Provider=SQLOLEDB.1; Data
Source=localhost;" + " Initial Catalog=Pubs; Integrated
// Making the connection
lblInfo.Text="<b>Server Version: </b>" + myConn.ServerVersion;
lblInfo.Text+="<br><b> Connection is:</b> " + myConn.State.ToString();
} catch(Exception err) {
lblInfo.Text = "Error reading the database.";
lblInfo.Text += err.Message;
} finally {
lblInfo.Text += "<br> Now Connection is";
lblInfo.Text += myConn.State.ToString();
//Alternative connection
lblInfo.Text="<b>Server Version: </b>" + myConn.ServerVersion;
lblInfo.Text+="<br><b> Connection is:</b> " + myConn.State.ToString();
lblInfo.Text += "<br> Now Connection is";
lblInfo.Text += myConn.State.ToString();
// Creating the SQL statement and assigning to Command
<x>Command myCmd = new <x>Command();
myCmd.Connection = myConn;
myCmd.CommandText = "Select * from Authors";
<x>Command myCmd = new <x>Command("Select * from Authors", myConn);
// Using Command with DataReader
<x>DataReader myReader;
myReader = myCmd.ExecuteReader();
// Reading objects
myReader.Read(); // reads an object at a time sequentially
// Cleanup
ADO.Net - command parameters
Instead of using this:
insertSQL "Insert INTO authors (au_id) VALUES ('txtID.Text')"
.... where txtID is a from the GUI on the webpage.
This method can be hacked via SQL Injection. To solve this, Command
Parameters are used:
insertSQL "Insert INTO authors (au_id) VALUES (?)"
cmd.Parameters.Add("?", txtID.Text);
where cmd is a OleDBCommand, and note that "?" is for OleDB only.
MySQL or MSSQL may have different symbols or notation for their
command parameters.
// don't ever do this!
// SqlCommand cmd = new SqlCommand(
// "select * from Customers where city = '" + inputCity + "'";
// 1. declare command object with parameter
SqlCommand cmd = new SqlCommand(
"select * from Customers where city = @City", conn);
// 2. define parameters used in command object
SqlParameter param = new SqlParameter();
param.ParameterName = "@City";
param.Value = inputCity;
// 3. add new parameter to command object

ADO.Net - Data Binding
Simple Data Binding:
1) in the aspx page, have something like:
<asp:Label id="lbLabel" runat="server">
There were <%# TransactionCount %>
2) In the code behind, have something like:
private void Page_Load(...){
TransactionCount = 10;
Alternative to data bind above is to do this in-code.
3) private void Page_Load(...){
TransactionCount = 10;
lblDynamic.Text = "There were " + TransactionCount.ToString();
Multiple Binding:
1. Form an array list from whereever:
eg. ArrayList fruit = new ArrayList();
or from database
2. Define binding for list controls; eg
MyListBox.DataSource = fruit;
MyDropDownListBox.DataSource = fruit;
MyHTMLSelect.DataSource = fruit;
MyCheckBoxList.DataSource = fruit;
MyRadioButtonList.DataSource = fruit;
3. Activate the binding, eg.
this.DataBind(); // this refers to the current page.

Multiple Binding with hashtables:
1. Create hashtable with key,val pair
Hashtable fruit = new Hashtable();
fruit.Add(1, "Kiwi");
fruit.Add(2, "Pear");
2. Binding specific fields
MyListBox.DataTextField = "Value" -> put the Value of hastable
into the Text of the Control
MyListBox.DataValueField = "Key" -> put the Key of hastable into
the value of the Control
3. Define databinding and activate
MyListBox.DataSource = fruit;
4. The result is the following HTML will be rendered:
<select name="MyListBox" id="MyListBox">
<option value="1">Kiwi</option>
Databinding with databases:
1. Some possible namespaces (when using OleDB):
using System.Data;
using System.Data.OleDb;
2. Making data using dataset example:
DataSet ds = new DataSet();
DataRow dr = ds.Tables["Users"].NewRow();
dr["Name"] = "John";
dr["Country"] = "Uganda";
3. Bind table to data source:
lstUser.DataSource = ds.Tables["Users"];
lstUser.DataTextField = "Name";
or Bind whole DataSet to data source:
lstUser.DataSource = ds;
lstUser.DataMember = "Users";
lstUser.DataTextField = "Name";
4. Activate the Binding:
or to bind just the list box
ADO.Net - Data Binding - DataList
1. Code Behind:
public class BasicAuthorList: Page
protected DataList listAuthor;
// (Initialisation code omitted)
private string connectString ="Provider ......."
private void Page_Load(Object sender, EventArgs e)
OleDbConnection con = new OleDbConnection (connectString);
OleDbCommand cmd = new OleDbCommand(SQL, con);
OleDbAdapter adapt = new OleDbAdapter(cmd);
DataSet pubs = new DataSet();
adapter.Fill(pubs, "Authors");
//Bind the DataSet and activate the data bindings for the page
listAuthor.DataSource = pubs.Tables["Authors"];
2. ASPX DataList template
<asp:DataList id=listAuthor runat="server">
<font face="Verdana" size="2">
<b><%# DataBinder.Eval(Container.DataItem, "au_fname") %>
<%# DataBinder.Eval(Container.DataItem, "au_lname") %></b></font>
<br> Address: <%# DataBinder.Eval(Container.DataItem, "address") %>
<br> City: <%# DataBinder.Eval(Container.DataItem, "city") %>
3. Formating Values - for DataBinder
eg DataBinder.Eval(Container.DataItem, "Price", "{0:C}")
{0:C} Currency
{0:E} Scientific (Exponential)
{0:P} Percentage
{0:F?} Fixed Decimal
see MSDN Help for more.
4. Adding different styles to Templates
a) Manual option - hand coding on aspx file
<h2> title </h2>
(Item style1)
(Item style2)
<h2> title </h2>
<h2> title </h2>
b) Using VS.Net right-click DataList properties
c) AutoFormat link from the DataList properties
d) To make columns and rows, check out the RepeatDirection and
RepeatColumns properties.

ADO.Net - Data Binding - DataGrid
1) DataList may have columns and rows, but DataGrid has columns such
that the columns
correspond to certain fields of the data item; eg phone - city - zip
code as different
2) Features include: automatic paging, sorting, editing, selecting.
3) Examples that show the Columns tag and the use of styles:
<asp: DataGrid id=gridauthor runat="server" AutoGenerateColumns="false"
BorderColor="#..." BorderStyle="None" CellSpacing="2"
BackColor="#..." CellPadding="3" BorderWidth="1px">
<FooterStyle ForeColor="#..." BackColor="#..." ></FooterStyle>
<HeaderStyle ForeColor="#..." BackColor="#..." ></HeaderStyle>
<ItemStyle ForeColor="#..." BackColor="#..." ></ItemStyle>
<asp:TemplateColumn HeaderText="AuthorName">
<%# DataBinder.Eval(Container.DataItem, "au_fname") %>
<%# DataBinder.Eval(Container.DataItem, "au_lname") %>
4) DataGrid has special columns including:
TemplateColumn - contents here include <ItemTemplate> and other stuff
that can go into
BoundColumn - a particular field from database
All these columns should exist within <Columns> ... </Columns>

ADO.Net - Data Binding - Repeater
Repeater has not much formatting by itself. It depends on formatting provided
in the html. Example:
<asp:Repeater id=repeatauthor runat="server">
<HeaderTemplate> <table> </HeaderStyle>
<%# DataBinder.Eval(Container.DataItem, "au_fname") %>
<FooterTemplate> </table> </FooterStyle>
ADO.Net - Styles and Templates summary
DataList DataGrid Repeater
AlternatingItemStyle AlternatingItemStyle None
EditItemStyle EditItemStyle
FooterStyle FooterStyle
HeaderStyle HeaderStyle
ItemStyle ItemStyle
SelectedItemStyle SelectedItemStyle
SeparatorStyle PagerStyle

DataList DataGrid* Repeater
AlternatingItemTemplate FooterTemplate AlternatingItemTemplate
EditItemTemplate HeaderTemplate FooterTemplate
FooterTemplate ItemTemplate ItemTemplate
HeaderTemplate EditItemTemplate SeparatorTemplate
* only supported by Template column
1) Do not bind the grid in the Page.Load event handler, otherwise info is
lost about which button user clicked or item selected.
private void Page_Load......
if(!this.PostBack) {
DataSet ds = GetDataSet();
private DataSet GetDataSet(){
string SQL = "...."
OldDbConnection ...
OldDbCommand cmd =
OleDbAdapter = ...
DataSet dsPubs = ...
adapter.Fill(dsPubs, "Authors");
return dsPubs;
private void BindGrid(DataSet ds){
gridAuthor.DataSource = ds.Table["Authors"];

Windows Service Applications
1. Do not have any in/output to screen or Windows, or it will crash the app.
2. Error messages should be logged in the Windows event log rather
than raised in the user interface.
3. To control, use Services Control Manager, or Server Explorer, or
the ServiceController class (use this
to control the service from another app).
4. States of the service include: start, stop, pause, resume
Corresponding methods in code: OnStart, OnStop, OnPause,
OnContinue, OnShutdown, OnCustomCommand, OnPowerEvent.
5. Two types of services: Win32OwnProcess, Win32ShareProcess.
6. VisualStudio has installation components that can install
resources, register the service and let Services Controller
Manager know. Add these installers to the app and also create a
separate setup project.
7. Must inherit from System.ServiceProcess.ServiceBase class. The
project must contain installation components.
To create the Service:
- set ServiceName property
- create installers
- override methods for OnStart and OnStop.
8. System.ServiceProcess.ServiceProcessInstaller and
—You use these classes to install and uninstall your service.
9. Execution Process:
Add Installers in project
Install: installutil yourproject.exe / Uninstall: installutil
/u yourproject.exe
Start the Service
10. Debugging:
Install service
Start service
In VS, Debug->Process
Click Show System Processes
Attach process
add any break points
use Services Control Manager to control the service.
11. To add Installers:
-In Solution Explorer, go to Design View of the service.
-Click on background of designer and AddInstaller.
-A new class, ProjectInstaller, and two installation components,
ServiceProcessInstaller and ServiceInstaller,
are added to your project, and property values for the service are
copied to the components.
-Click the ServiceInstaller component and verify that the value
of the ServiceName property is set to the
same value as the ServiceName property on the service itself.
-To determine how your service will be started, click the
ServiceInstaller component and set the StartType property
to the appropriate value. { Manual, Automatic, Disabled }
- To determine the security context in which your service will
run, click the ServiceProcessInstaller
component and set the appropriate property values. For more
information, see How to: Specify the Security Context for Services.
- Override any methods for which you need to perform custom
processing. For more information, see How to: Override Default Methods
on Installation Components.
- Perform steps 1 through 7 for each additional service in your project.
Note: For each additional service in your project, you must
add an additional ServiceInstaller component
to the project's ProjectInstaller class. The ServiceProcessInstaller
component added in step
three works with all of the individual service installers in the project.
- Create your setup project and custom action to deploy and
install your service.
For more information on setup projects, see Setup Projects.
- After you add installers to your application, the next step is to
create a setup project that will install
the compiled project files and run the installers needed to install
your service. To create a complete
setup project, you must add the service project's output to the
setup project and
then add a custom action to have your service installed. For more
information on setup projects, see Setup Projects. For more
information on custom actions, see Walkthrough: Creating a Custom
(see VS Setup Projects for more details)

VS Setup Projects
1. Design, code, build your project in VS Studio say project ProjA in
solution SolnA.
2. Create the setup project SetupA, in SolnA: Add Project -> New
Project -> Other Project Types -> Setup and Deployment.
3. Right click setupA -> Install -> Add Project Output. Select ProjA
and choose "Primary Output".
4. Right click setupA -> View -> Custom Actions.
5. Right click on Custom Actions -> Add Custom Option. Select
Application Folder -> Primary output from ProjA.
6. Build.
7. The msi and exe file will be created.

Understanding ADO.Net - from AppDev video tutorial
Object Model:
Connected Object (Specific to DB engine or provider)
-> .Net Data Provider (incl. MySql.Data.MySqlClient or
-> Connection: Transaction
-> Command: Parameters (eg to execute some command)
-> DataReader:
-> DataAdapter:
-> Fills DataTable: SelectComm
-> Updates Database: InsertComm, UpdateComm, DeleteComm
DisConnected Object (can work with data in a disconnected state)
-> DataSet (analogous to Database) <-> XML
-> DataTableCollection
-> DataTable:
-> DataRowCollection - storing the data
-> DataColumnCollection - names and properties of columns
-> ConstraintCollection - eg unique key or foreign key constraints.
-> DataRelationCollection
-> DataView
-> Row Filter
-> Sort
-> Extended support for Data Binnding
-> DataTableReader
-> A DataReader for DataTables and DataSets
-> Fast forward only reading
-> resilient to adding or deleting rows while reading

... to be continued at Data Caching Object
Using MySQL in Visual Studio
1. View -> Server Explorer
2. Look for database server and connect
Configuring MySQL with ASP.Net
It is easy to use MySQL with ASP.Net. becasue by default the local
ASP.Net enables you with FULL TRUST permission.
This section shows how to configure ASP.Net to work with MySQL where
the ASP.Net is stored in a ISP's server,
which usually uses MEDIUM TRUST, not FULL TRUST.
To the SQL administrator:
1. There are two options, one is to modify the web_mediumtrust.config;
the other option is to copy and rename the config file.
The web_mediumtrust.config is located typically in
Add the SOCKPermission to this file.
<SecurityClass .............
<SecurityClass Name="SocketPermission"
Description="System.Net.SocketPermission, System, Version=,
Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
2. If we choose the second option in step 1. to make a new file and
called web_mediumMySQLtrust.config, then we need
to register this in the
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG\web.config with
the following line:
<trustLevel name="Medium" policyFile="web_mediumtrust.config" />
.... already there
<trustLevel name="MediumMySQL"
policyFile="web_mediumMySQLtrust.config" /> .... add this new one
Also in the same file, add this within the <system.web>
<trust level="Medium" originUrl="" />
<trust level="MediumMySQL" originUrl="" />

To the Developer:
1. In the web application, in the web.config file, insert the line
about <trust> just before </system.web>
<trust level="Medium" originUrl="" />

To add first element, add a ListItem and the property
AppendDataBoundItems set to true.
<asp:dropdownlist id="suburbDropList" AppendDataBoundItems="true"
AutoPostBack="True" runat="server" >
<asp:ListItem Text="(Select a Suburb)" Value="" />
DataGrid - Sorting
To allow for sorting on the DataGrid, the following are needed.
1. Right click on the GUI design of the DataGrid and set
"AllowSorting" to "true".
2. Add the following in the aspx code file in the DataGrid item:
OnPageIndexChanging="PageChangeFunction" OnSorting="SortingFunction"
3. Set property AutoGenerateColumns to true,
i.e.TestMenu.AutoGenerateColumns = true;
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)
Version: since .Net 2.0
Summary: Displays the values of a data source in a table where each
column represents a field and each row represents a record. The
GridView control allows you to select, sort, and edit these items.
Event: OnRowDataBound()
- can be used to set the width of the grid view once data is bound.
- Example:
protected void gvShop_RowDataBound(object sender, GridViewRowEventArgs e)
if (e.Row.RowType != DataControlRowType.DataRow) return;
GridView gv = (GridView)sender;
//e.Row.Cells[0].Width = 100; // Free Size
e.Row.Cells[1].Width = 100; //name
e.Row.Cells[2].Width = 300; //address

GridView - Sorting
This describes how to implement the sorting event of a GridView object.
1. Sorting must be allowed in the GridView object. On the aspx page,
the GridView object must look something like:
<asp:GridView ID="gvShop" runat="server" AllowSorting="True"
OnSorting="gvShop_Sorting" >
The important properties are AllowSorting set to True and OnSorting
specified with the name of the method that performs the sorting. By
Default, the event name is given by the object ID (gvShop) combined
with the event (Sorting) hence the name gvShop_Sorting.
2. Before implementing the GridView sorting event, let us define two
strings at the start of the class.
private const string ASCENDING = " ASC";
private const string DESCENDING = " DESC";
These specific strings ASC and DESC are required in the sorting
expressions later.
3. Define the property called gvSortDirection - to hold the state of
whether it is currently sorted in ascending or descending fashion.
public SortDirection gvSortDirection {
get {
if (ViewState["sortDirection"] == null)
ViewState["sortDirection"] = SortDirection.Ascending;
return (SortDirection)ViewState["sortDirection"];
set { ViewState["sortDirection"] = value; }
4. Finally, the sorting event is implemented as below:
protected void gvShop_Sorting(object sender, GridViewSortEventArgs e)
string sortExpression = e.SortExpression;
string strSort = null;
if (gvSortDirection == SortDirection.Ascending)
gvSortDirection = SortDirection.Descending;
strSort = sortExpression + " " + DESCENDING;
gvSortDirection = SortDirection.Ascending;
strSort = sortExpression + " " + ASCENDING;
DataTable dc1 = (DataTable)gvShop.DataSource;
dc1.DefaultView.Sort = strSort;
A few things to note:
- when the user press on the header of the column, the data will be
sorted in ascending, then descending way alternately. This is possible
by the if loop which changes the direction of the sorting each time it
is sorted.
- the strSort is made up of the name of the column to be sorted, and
whether it is ascending or descending.
- The most important step is to assign the DefaultView.Sort = strSort.
Note that in this case, the GridView was originally sourced from a
DataTable, hence in this example, the DataSource is casted into a
DataTable dc1 object. Finally the GridView need to be binded.

GridView - Selecting Rows, Clickable Rows
In ASP.Net, a simple GridView presents a table with rows of data, in
different columns. All the data are usually obtained from some
DataSource which may come from a database. This section shows how to
add an Extra column where all the entries in this column are clickable
and is linked to the row on which it is clicked. An example of a
Gridview with the Extra column as the first column:
clickable Col 1 Col 2
select John Smith
select Jane Doe
select Alice Wong
select Bob Chan
In the example, the first row are column names. Each of the "select"
words are clickable and can be used to launch an action, and identify
which row was clicked. The implement of this involves the following
1. On the aspx page, the code looks like:
<asp:GridView ID="gvShop" runat="server" AllowSorting="True"
OnSorting="gvShop_Sorting" >
<RowStyle BackColor="#FFFBD6" ForeColor="#333333" />
<SelectedRowStyle BackColor="#FFCC66" Font-Bold="True"
ForeColor="Navy" />
<asp:BoundField ReadOnly="True" >
<ItemStyle Width="0px" />
<asp:TemplateField HeaderText="clickable">
<asp:LinkButton ID="lnk_ShopName" runat="server" Text="select"
Tooltip="some tip"
CommandArgument='<%# Eval("Col 1") %>'
style="background-image: url(images/icon.gif);"
The important things to note are the following:
- The <asp:TemplateField> tag - see the word "clickable" as the name
of the column. The TemplateField can be generated from the GUI in the
Design mode of the aspx page, by right clicking the GridView rectangle
and right clicking the top right corner and select "edit columns".
- The <ItemTemplate> tag - this contain a LinkButton object whose Text
is "select". So the words "select" is displayed in the GridView
- The CommandArgument is very important, the argument inside Eval,
must be exactly the same name as one of the column names. This means
that when a row is clicked, the CommandArgument will take the value at
that row of the specified column. In this example, Eval("Col 1") means
either John, Jane, Alice or Bob will be taken along the event.
- Instead of the words "select", an image or icon can be used, and
this is done by the background-image attribute in the LinkButton.
- For the event to do something it has to be linked. Here the
LinkButton is connected to the function called "lnk_ShopName" which is
called whenever an event occurs.
2. Implementing the event or action on the aspx.cs page. In this
example, the event triggers the method called "lnk_ShopName" to be
executed. The method can be something like:
protected void lnk_ShopName_Click(object sender, EventArgs e)
System.Web.UI.WebControls.LinkButton linkBut;
linkBut = (LinkButton)sender;
string sName = linkBut.CommandArgument;
// do something with sName
The information about which row is clicked can be extracted from the
sender object.
Since the Control was a LinkButton, the sender is cast into the LinkButton.
The CommandArgument will contain the data at the row that was clicked,
at the column specified in the Eval argument on the aspx page. In this
case, Col 1 was chosen as the column.

WebService in ASP.Net
*.asmx - web service file
WSDL - Web Service Description Language, describes the methods
and parameters in a web service.
The elements of WSDL are: definitions, types, message,
portType, binding, service.
SOAP - way to encode info to pass to web service
HTTP - protocol through which SOAP messages are sent
DISCO - discovery standard that contains links to web services
UDDI - business registry that lists all info about companies
and web services they provide, with
URLs for their WSDL contracts and DISCO.
Data types: Basic / primitives, Enumerations, DataSets, XmlNode,
Custom Objects, Arrays

Testing the web service
http://<domain>/<webservice>.asmx -> to view the web service directly
http://<domain>/<webservice>.asmx?WSDL -> to view the WSDL.
http://<domain>/<webservice>.asmx?op=<methodName> -> to access
the web service method directly
The use of web services in C# ASP.Net is illustrated with the example below:
1.<%@ WebService Language="C#" Class="Util" %>
2. using System.Web.Services;
3. using System;
4. [WebService(Namespace="")]
5. public class Util: WebService
6. {
7. [ WebMethod]
8. public long Multiply(int a, int b)
9. {
10. return a * b;
11. }
12. }
in file: Util.asmx
1.«%@ WebService Language="C#" CodeBehind="Util.asmx.cs" Class="Util" %»
in file: Util.asmx.cs
2. using System.Web.Services;
3. using System;
4. [WebService(Namespace="", Description="test utility")]
5. public class Util: WebService
6. {
7. [WebMethod(Description=" test a method "]
8. public long Multiply(int a, int b)
9. {
10. return a * b;
11. }
12. }
1. Declare the webservice using «%@ WebService....
Option 1: Place the above code inside *.asmx file with the C# code.
Option 2: Put only the <%@ WebService in the asmx class and put the C#
code somewhere else.
Then the declaration would be:
<%@ WebService Language="C#" Class="MyName.MyWebService,MyAssembly" %>
... where MyAssembly is the name of the assembly.
2. Deriving the WebService class - this is optional. Lines 2,5.
3. Apply WebService attribute and specify domain to avoid confusion
with other webservices.
see line 4.
4. Define the web service method using [ WebMethod ] - see line 7.
5. State Management for Web Services is achived by deriving from the
WebService class. It provides
access to ASP.NET objects such as:
Session - client specific state information
Application - used to store data globally and available to all clients
Server - utility functions
User - info about current client including authentication
Context - provides access to Request, Response and Cache
7. Storing and access state in a client session:
Declare: [ WebMethod(EnableSession=true) ]
Store: Session["MyServiceUsage"] = 1;
Access: Session["MyServiceUsage"] = ((int) Session["MyServiceUsage"]) + 1;
8. Storing and access state in Web application hosting the Web service:
Declare: [ WebMethod ]
Store: Application["appMyServiceUsage"] = 1;
Access: Application["appMyServiceUsage"] = ((int)
Application["appMyServiceUsage"]) + 1;

ASP.Net Custom Control
The following describes Custom Control for web applications (*.aspx).
The Custom Control for console
applications are similar, but not exactly.
1. To add a user control, right click on the web application project
in the Solution Explorer. Click
New Item, then choose Web User Control, and name it WUC.

2. In Visual Studio, this will auto create 3 files:
- WUC.ascx - with Design and Code view
- WUC.ascx.cs - the code to be edited or added.
- WUC.ascx.designer.cs
3. Put the collection of controls in your custom control withing the
WUC.ascx file. For example,
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="WUC.ascx.cs"
Inherits="ParentWebApp.WUC" %>
<asp:Label ID="lblFooter" runat="server" Height="87px" Text="Label"
4. The Label control above can be also created by using the WUC.ascx
design view. Just
drag the Label button from the toolbox onto the form.
5. In the code behind file WUC.ascx.cs, make the WUC class inherit
from System.Web.UI.UserControl. And
in the Page_Load, enter code for what the controls need to do. For example,
public partial class WebUserControlFooter : System.Web.UI.UserControl
protected void Page_Load(object sender, EventArgs e)
lblFooter.Text = "This page was served at ";
lblFooter.Text += DateTime.Now.ToString();
6. To use this custom control on any aspx web page:
a) Register the custom control on those aspx web pages, eg.
<%@ Register TagPrefix="cr" TagName="WUC" Src="~/WUC.ascx" %>
b) Add the custom control, eg.
<cr:WUC id=Footer1 runat="server" />
Note that the TagPrefix name is the alias for the custom control to be
used in the aspx web page.
\r\n - Carriage Return, then Newline - this is neeeded for
example in TextBox component.
How to Add Google Maps to your ASP.Net page
1. In Visual Studio, go to the aspx page where you want to include the
Google Map.
For example, if the aspx page is called test.aspx, then in the
Solution Explorer there is at least 3 code files:
- test.aspx.cs
- test.aspx.designer.cs
For this example, choose the test.aspx. In the main editor panel, look
at the grey bar below the panel and ensure it is "Design" and not
2. Add HTML components
Open the Toolbox. Either by View -> Toolbox or go to the right panel
and select the Toolbox tab.
Then in the Toolbox, go to the HTML section of components. Do not
remain at the Standard section of components.
Drag and drop the following onto the page:
- Input(Button) - for activating / drawing the map
- Input(Hidden) - for lattitude information
- Input(Hidden) - for longitude information
- Input(Hidden) - for other information to be printed on the map
- Div - actual area where map is displayed.
Click on each one of the components, and name them in the "id" field
with these names:
3. Make HTML components into ASP.NET components.
From the GUI editor page, click on the "Source" tab to edit the html
source code.
Go to the HTML section where the above 5 components are defined and
add the following for each 5 components: runat="server".
The final HTML code for the 5 components should look like:
Map Display
<input id="butMap" runat="server" type="button" value="Draw
Map" onclick="drawGmap()" />
<input id="hidLatitude" runat="server" type="hidden" />&nbsp;
<input id="hidLongitude" runat="server" type="hidden" />
<input id="hidShopDetails" runat="server" type="hidden" />
<div id="map" runat="server" style="width: 400px; height:
400px" visible="true"> </div>
At this stage just make sure the attributes of id, type and runat are correct.
By adding the runat="server" to the HTML code, then compile the code
in Visual Studio, this would make the HTML elements recognizable by
To check this, go to the test.aspx.designer.cs file and check the
following lines exist after compilation with runat="server":
protected global::System.Web.UI.HtmlControls.HtmlInputButton butMap;
protected global::System.Web.UI.HtmlControls.HtmlInputHidden
protected global::System.Web.UI.HtmlControls.HtmlInputHidden
protected global::System.Web.UI.HtmlControls.HtmlInputHidden
protected global::System.Web.UI.HtmlControls.HtmlGenericControl map;
4. Ensure that somewhere in the test.aspx.cs code file, the html input
fields on the front end are filled with values. For example:
hidDetails.Value = "some details";
hidLatitude.Value = "20.312";
hidLongitude.Value = "132.12";

5. In between the header and the body section of the html code:
<script type="text/javascript"
<script type="text/javascript"> google.load("maps", "2.x"); </script>
<script type="text/javascript">
function drawGmap() {
var dLat = document.getElementById("hidLatitude").value;
var dLong = document.getElementById("hidLongitude").value;
var sAddress = document.getElementById("hidDetails").value;
var map = new google.maps.Map2(document.getElementById("map"));
var point = new GLatLng(dLat, dLong);
map.addOverlay(new GMarker(point));
map.setCenter(new google.maps.LatLng(dLat, dLong), 15);
var shtml = "100 <b>He</b>llo";
map.openInfoWindowHtml(map.getCenter(), sAddress);
<body onunload="GUnload()">
In addition, ensure that the button or some other component call the
function drawGmap(). For example, from the above HTML Button :
<input id="butMap" runat="server" type="button" value="Draw
Map" onclick="drawGmap()" />

ASP.Net inline Tags <%...%>
These are tags that may be used on the aspx / html page, that enable
interaction with server side functions. The tags and a brief
explanation is given below:
<% ... %>
Allows C# code to be run within the tags.
<% string s = "test"; %>

<%= ... %>
Extracts values from server side objects.
<%= DateTime.Now.ToShortDateString() %>

<%# .. %>
Mostly used for binding expressions like Eval or Bind
Example: usage in Gridview in the example below where the Eval is used
to extract the value in the DB under the "name" column or field, for
each row in the Gridview.
<asp:GridView ID="GridView1"
runat="server" AutoGenerateColumns="False"
<asp:TemplateField HeaderText="Name">
<asp:LinkButton ID="lnkname" runat="server"
Text='<%#Eval("Name") %>'
PostBackUrl='<%#"~/Details.aspx?ID="+Eval("ID") %>'>
<%$ ... %>
This is also called ASP.Net Expression and is used to extract
AppSettings, ConnectionsStrings or Resources
Example: using as connection string in DB
<asp:SqlDataSource ID="party" runat="server" ConnectionString="<%$
ConnectionStrings:myString %>" SelectCommand="SELECT * FROM [table]"
<%@ ... %>
Specifying ASP.Net directives at the top of the aspx page.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Test.aspx.cs"
Inherits="_parent" Title="Test Page" %>

<%-- ... --%>
Comments are embedded here. These comments can be seen on the aspx
page, but after compilation into html page, the client would not be
able to see these parts.
<%-- Here are some comments --%>

ASP.Net calling Javascript client side
This section shows how to call a Javascript function defined on the
aspx page, from the C# code-behind aspx.cs code.
1. The javascript is defined in the aspx page between the head and
body tags, like:
<script type="text/javascript">
function drawGmap() { ......}
2. In the aspx.cs page, to call the javascript function drawGmap(...),
if (!Page.ClientScript.IsStartupScriptRegistered("alert")) {
Page.ClientScript.RegisterStartupScript(this.GetType(), "alert",
"drawGmap();", true);
The name of the function is simply placed at the third position.

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