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Overview
In this article I will demonstrate a
technique for retrieving Extensible Markup Language (XML)
data from a SQL Server over the web, and then applying Extensible
Stylesheet Language (XSL) to the returned data and outputting
HTML directly to your eVB application.
Requirements
- Optional: XML Support Installed on
SQL Server 2000, check out the XML support in Microsoft®
SQL Server™ 2000. (NOTE: if you do not have access
to SQL Server with XML support installed, I have included
pre-generated files for the sample application.)
- WebBrowserCE, a web browser
control for eVB, download
a trial version.
- MSXML version 2.0 (msxml.dll).
The Application
With the next generation of pocket
applications XML will be the primary transport mechanism
for data from information sources like a databases or web
services. That said, how can developers robustly output
XML data to Pocket PC users. One approach I will explore
in this article is using HTML from an eVB application using
the
WebBrowserCE control from IntelProg.com.
Setting Up the Application
When using XML from eVB you will need
to set references to the MSXML.dll and the WebBrowserCE
1.0 Type library. For detailed instruction on registering
the WebBrowserCE library for your device, see the ReadMe.txt
file included with the control. Additionally, copy the Employees.xml,
Employees.xsl, EmployeesDetail.xsl and NWINDTRADERS.gif
files to the “\windows\start menu\” directory
in emulation or your device.
Reference Microsoft XML, version
2.0 and WebBrowserCE 1.0 Type Library
Requesting XML Data
Now, for the fun stuff. Here
is a snippet of the Employees.xml file that we will transform
with XSL.
If you do not have SQL Server with SQLXML
support you can use the static XML file include with the
source code. Be sure to make the necessary changes to the
BuildDirectory subroutine described in the code comments.
SQL Server XML support is a very powerful technology that
allows extremely fast retrieval of XML directly from a SQL
Server via HTTP protocol. For more information, see Microsoft®
SQL Server™ 2000.
To begin we need to define several global
level variables to handle the XML and XSL document objects
and the WebBrowserCE control.
'Global XML object
Public gXMLDoc As MSXML.DOMDocument
'Global XSL object
Public gXSLDoc As MSXML.DOMDocument
'WebBrowser Control
Public objHtml As WEBBROWSERCELib.HTMLViewerCtl
'HTML to render
Public gsHTML As String
'XMLSQL Service URL
Public gURL As String
In the Form_Load event handler of the
main form, add the following code.
Set objHtml = CreateObjectWithEvents("WebBrowserCE.HTMLViewerCtl",
"HTMLView_")
'Full version requires license'
objHtml.LicenseKey = ""
objHtml.create (frmContainer.hWnd)
'Define Initial Position of HTML control
objHtml.Left = 0
objHtml.Top = 49
objHtml.Width = 240
objHtml.Height = 195
'Define Service URL, NOTE: you can use
a template xml file instead of submitting query directly
gURL= _ "http://YOURSERVER/NWINDS?SQL=Select+*+from+Employees+order+
by+LastName+for+xml+raw&root=EmployeesList"
Call BuildDirectory
The proceeding code will instantiate
the WebBrowserCE control, and assign the start up location
and size. Now we can call the BuildDirectory subroutine
to display the text. This subroutine wraps the call the
SQL server and displays the HTML output.
We can then load the XML directly into
our global XMLDOM object with the loadXML method, which
in turn calls the GetXMLByHTTP function.
Set gXMLDoc = CreateObject("Microsoft.XMLDOM")gXMLDoc.loadXML
GetXMLByHTTP(gURL)
The GetXMLByHTTP function makes
a HTTP request to SQL Server for our XML data using the
XMLHTTP object. Notice we are returning our XML data as
a string variable that has been stripped of encoding and
reference entities replaced.
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