Beginning Web Development, Silverlight, and ASP.NET AJAX

CHAPTER 7 ■ .NET 3.0: WINDOWS COMMUNICATION FOUNDATION 169
As you can see, this is just a straightforward class implementation. The idea is that
your “custom” code to define a WCF service exists outside of your implementation code,
and is configured via a Web.config file. This means that the business logic developers concentrate
on the business logic and don’t wrap it up in the plumbing. It’s a very neat aspect
of the WCF design that will make the implementation of enterprise-grade services easy.
Next, you build the operation itself. Here’s the code:
public string GetAddresses(string strZIP)
{
string strReturn = "";
AddressDataTableAdapters.AddressTableAdapter da =
new AddressDataTableAdapters.AddressTableAdapter();
AddressData.AddressDataTable dt = da.GetData(strZIP);
strReturn = FormatDTasXML(dt);
}
return strReturn;
This takes in a string, the ZIP code, and uses it as a parameter in pulling the address
data (as a DataTable) from the AddressTableAdapter, which is implemented by the
DataSet. Then it sends this data to a helper function to format it as XML and serialize it
into a string. This string will then be returned by the service.
Here’s the listing for this helper function:
private string FormatDTasXML(AddressData.AddressDataTable dt)
{
MemoryStream memStream = null;
XmlTextWriter xmlWriter = null;
try
{
memStream = new MemoryStream();
xmlWriter = new XmlTextWriter(memStream, Encoding.Unicode);
dt.WriteXml(xmlWriter);
int count = (int)memStream.Length;
byte[] arr = new byte[count];
memStream.Seek(0, SeekOrigin.Begin);
memStream.Read(arr, 0, count);
UnicodeEncoding utf = new UnicodeEncoding();
return utf.GetString(arr).Trim();