Webmaster''''s Guide to the Wireless Internet part 44 docx

So in this case, if the user were using a Web browser, the BMP file would be displayed, as shown in Figure 9.35.. On the UP.SDK, the WBMP file would be selected, as shown in Figure 9.36.

Figure 9.34 Image.aspx

<%@ Page Inherits="System.Web.UI.MobileControls.MobilePage"

Language="VB" %>

<%@ Register TagPrefix="Mobile" Namespace="System.Web.UI.MobileControls" Assembly="System.Web.Mobile" %>

<Mobile:Form runat="server">

<Mobile:Label>Photo of myself</Mobile:Label>

<Mobile:Image runat=server alternateText="[My Photo here]">

<DeviceSpecific>

<Choice Filter="isHTML32" ImageURL="myself.bmp" />

<Choice Filter="isWML11" ImageURL="myself.wbmp" />

</DeviceSpecific>

</Mobile:Image>

</Mobile:Form>

Within the <DeviceSpecific> control, you have the <Choice> elements In the preceding program, each choice element contains two attributes—Filter and ImageURL So in this case, if the user were using a Web browser, the BMP file

would be displayed, as shown in Figure 9.35.

On the UP.SDK, the WBMP file would be selected, as shown in Figure 9.36.

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Figure 9.35 Displaying the BMP File in a Web Browser

The <Choice> elements are evaluated according to the order in which they appear in the <DeviceSpecific> control If none of the <Choice> elements evaluates true, the string “[My Photo here]” would be displayed.The Filter attribute con-tains values that are matched from the <deviceFilters> element in the web.config

configuration file (see Figure 9.37).

The web.config file contains the various device filters Figure 9.37 shows a

portion of the web.config file A device may match several <filter>s For example,

a Web browser satisfies the isHTML32 and the prefersGif filter.The compare attribute of the <filter> element specifies the capability evaluated by the compar-ison evaluator and the argument attribute specifies the argument against which the

capability should be compared.

To illustrate using the preceding example, a WAP device will match the

isWML11 filter, which will in turn match the second <Choice> element:

<Choice Filter="isHTML32" ImageURL="myself.bmp" />

<Choice Filter="isWML11" ImageURL="myself.wbmp" />

Figure 9.37 Web.config

<deviceFilters>

<!— Markup Languages —>

<filter name="isHTML32" compare="preferredRenderingType"

argument="html32" />

<filter name="isWML11" compare="preferredRenderingType"

argument="wml11" />

<filter name="isCHTML10" compare="preferredRenderingType"

argument="chtml10" />

<!— Device Browsers —>

<filter name="isGoAmerica" compare="browser"

argument="Go.Web" />

<filter name="isMME" compare="browser"

argument="Microsoft Mobile Explorer" />

<filter name="isMyPalm" compare="browser"

argument="MyPalm" />

<filter name="isPocketIE" compare="browser"

argument="Pocket IE" />

<filter name="isUP3x" compare="type"

argument="Phone.com 3.x Browser" />

<filter name="isUP4x" compare="type"

argument="Phone.com 4.x Browser" />

<!— Specific Devices —>

<filter name="isEricssonR380" compare="type"

argument="Ericsson R380" />

<filter name="isNokia7110" compare="type"

argument="Nokia 7110" />

<!— Device Capabilities —>

<filter name="prefersGIF" compare="preferredImageMIME"

argument="image/gif" />

<filter name="prefersWBMP" compare="preferredImageMIME"

argument="image/vnd.wap.wbmp" />

<filter name="supportsColor" compare="isColor"

argument="true" />

<filter name="supportsCookies" compare="cookies"

argument="true" />

<filter name="supportsJavaScript" compare="javascript"

argument="true" />

<filter name="supportsVoiceCalls" compare="canInitiateVoiceCall"

argument="true" />

</deviceFilters>

www.syngress.com

Figure 9.37 Continued

Validation Controls

There are quite a few validation controls available in the Microsoft Mobile Internet Toolkit SDK:

■ CompareValidator Compares two controls using a specified operator.

■ CustomValidator Allows customized validation of controls.

■ RangeValidator Validates the value of a control to ensure that it falls within a specified range.

■ RegularExpressionValidator Validates the value of a control by speci-fying a regular expression.

■ RequiredFieldValidator Ensures that a field is supplied a value.

■ ValidationSummary Displays the summary of all errors that occurred during the rendering of a form.

To see how they work, let’s consider the example shown in Figure 9.38.

Figure 9.38 Validation.aspx

<%@ Page Inherits="System.Web.UI.MobileControls.MobilePage"

Language="VB" %>

<%@ Register TagPrefix="Mobile" Namespace="System.Web.UI.MobileControls"

Assembly="System.Web.Mobile" %>

<script language="vb" runat=server>

Sub Submit_OnClick(sender as Object, e as EventArgs)

if (Page.IsValid) then ActiveForm = Form2 Result.Text = "The month you have entered was " & month.Text end if

End sub

</script>

<Mobile:Form id="Form1" runat=server>

<Mobile:RangeValidator runat=server ControlToValidate="month"

Type="Integer"

MinimumVaLue="1">

The month is not correct Please try again

</Mobile:RangeValidator>

<Mobile:Label runat=server>Please enter your birth month</Mobile:Label>

<Mobile:TextBox id="month" Numeric="true" runat=server/>

<Mobile:Command OnClick="Submit_OnClick"

runat=server>Submit</Mobile:Command>

</Mobile:Form>

<Mobile:Form id="Form2" runat=server>

<Mobile:Label id="Result" runat=server/>

<Mobile:Link Text="Back" navigateURL="#Form1" runat=server/>

</Mobile:Form>

In this example, we use the <Mobile:RangeValidator> control to validate the

range of a number.

<Mobile:RangeValidator runat=server ControlToValidate="month"

Type="Integer"

MaximumValue="12"

MinimumVaLue="1">

The month is not correct Please try again

</Mobile:RangeValidator>

Once the number is entered and the button is clicked, the Submit_OnClick() subroutine is invoked.The IsValid property will validate the range of the number

entered If the validation fails, the message “The month is not correct Please try again” is displayed; otherwise Form2 will be loaded.

Sub Submit_OnClick(sender as Object, e as EventArgs)

if (Page.IsValid) then ActiveForm = Form2 Result.Text = "The month you have entered was " & month.Text

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Figure 9.38 Continued

End sub

Figure 9.39 and Figure 9.40 show the output as displayed by the Pocket PC emulator and the UP.SDK, respectively.

Paginations

In an earlier section we saw the use of the <Mobile:List> control It is possible

that the list of items within the control might be long Anyone who has written a WAP application can attest to the importance of keeping the list short, at least per screen A common technique is to display the list in multiple pages, and as

such this technique is commonly known as records paging One of the great

fea-tures of the Mobile API is its auto-paging capability Consider the example shown in Figure 9.41.

Figure 9.41 Paginate.aspx

<%@ Page Inherits="System.Web.UI.MobileControls.MobilePage"

Language="VB" %>

<%@ Register TagPrefix="Mobile" Namespace="System.Web.UI.MobileControls"

Assembly="System.Web.Mobile" %>

Figure 9.39 Using the Validator Controls on the Pocket PC

Figure 9.40 Using the Validator Controls on the UP.SDK

<script language="vb" runat=server>

Sub Select_Item (sender as Object, e as ListCommandEventArgs)

End Sub

</script>

<Mobile:Form runat="server" id="form1"

paginate="true"

PagerStyle-NextPageText="Go to Page {0}" PagerStyle-PreviousPageText="Back to Page {0}">

<Mobile:Label runat="server" StyleReference="title" Text="Books in the net Developer Series" />

<Mobile:Label runat="server" id="PageNo"/>

<Mobile:List runat="server" id="titles"

OnItemCommand="Select_Item">

<Item value="1" text="VB net Developer's Guide"/>

<Item value="2" text="XML Developer's Guide to Web Based EDI"/>

<Item value="3" text="C#.net Developer's Guide"/>

<Item value="4" text="ASP.net Developer's Guide"/>

<Item value="5" text=".net Mobile Web Developer's Guide"/>

<Item value="6" text="ADO.net Developer's Guide"/>

<Item value="7" text="Web Services Developer Guide"/>

</Mobile:List>

</Mobile:Form>

Our list contains seven items.When loaded using the UP.SDK, we see that the list is displayed in multiple cards (see Figure 9.42).

www.syngress.com

Figure 9.41 Continued

Figure 9.42 Paginating a Form

control and set it to “true” Additionally, the PagerStyle-NextPageText and the

PagerStyle-PreviousPageText attributes allow you to set the message for displaying the

next and previous page, respectively.

<Mobile:Form runat="server" id="form1"

paginate="true"

PagerStyle-NextPageText="Go to Page {0}"

PagerStyle-PreviousPageText="Back to Page {0}">

Calendar Control

Apart from those regular controls like Label and Textbox, the Microsoft Mobile Internet Toolkit also includes some interesting controls like the Calendar and AdRotator controls.We will illustrate the use of the Calendar control in this section.

Date selection is a commonly used feature of mobile applications and in the past, great efforts have gone into making date selection as easy and error-proof as possible Instead of spending time in building the date selection module, the Mobile API has included the Calendar control Consider the example shown in Figure 9.43.

Figure 9.43 Birthdate.aspx

<%@ Page Inherits="System.Mobile.UI.MobilePage" Language="VB" %>

<%@ Register TagPrefix="Mobile" Namespace="System.Mobile.UI" %>

<script language="VB" runat="server">

Sub date_Changed(sender as Object, e as EventArgs) message.Text = "So your birthdate is " & birthdate.SelectedDate End Sub

</script>

<Mobile:Form id="Form1" runat="server">

<Mobile:Label runat="server" styleReference="Title" Text="Tell me your birthdate!"/>

<Mobile:Calendar id="birthdate" OnSelectionChanged="date_Changed"

runat="server"/>

Continued

<Mobile:Label runat="server" id="message"/>

</Mobile:Form>

Figure 9.44 and Figure 9.45 shows how our code appears in the various emulators.

When a date has been selected, the message in Figure 9.46 is printed.

www.syngress.com

Figure 9.43 Continued

Figure 9.44 Using the Calendar Control on the Pocket PC

Figure 9.45 Using the Calendar Control on the UP.SDK

Figure 9.46 Printing the Birth Date

to mm/dd/yyyy format), you can use the following properties:

message.Text = "So your birthdate is " & birthdate.SelectedDate.day

or

message.Text = "So your birthdate is " & birthdate.SelectedDate.month

or

message.Text = "So your birthdate is " & birthdate.SelectedDate.year

Accessing Data with ADO.NET

Today, most applications of any respectable size involve database access in one way

or another Developers are familiar with using the ActiveX Data Objects (ADO) for accessing databases thorough OLE DB and ODBC In anticipation of the increasing trend of distributed computing and the need to access data remotely, ADO.NET was evolved to support disconnected data access Actually, ADO.NET

is more of an evolution, rather than a revolution If you are familiar with ADO, chances are you will find most of the concepts in ADO.NET similar.

In the next section, we will take a closer look at ADO.NET and at how you can get started with it quickly.

A Brief Look at ADO.NET

If you are familiar with ADO, you should know that the Recordset object in ADO is no longer available in ADO.NET Figure 9.47 sums up the architecture

of ADO.NET.

In place of the Recordset object, in ADO.NET there are two new objects for data access.They are:

■ Dataset

■ DataReader

A Dataset object basically represents a complete set of data including related tables, constraints, and relationships among the tables.Think of a Dataset object as

a static cursor in ADO, but instead of storing only a single table, it stores multiple tables A DataReader object is used for reading records in a forward-only fashion.

Think of a DataReader object as a forward-only cursor in ADO.