Existing WCF service of xml transformation , need to integrate with MEF? - wcf

Question

My application is in WCF of xml transformation. now need to change to integrate with MEF. which is the best way to implement MEF or which type of architecture should i use to implement with less effort and less change in existing code?
EDIT
Explanation:
I have four hotel xml transformation
in wcf service. At one end it is fixed
format xml and another end different
xml format for each new hotel.and
another 20 hotel work will come. for
this repetative work i need some
re-usable and extendable architecture.
i want to convert existing
architecture upgrade with MEF for
future perspective. so i can do better
for next 20 hotel xml transformation.

Answer 1

How are you doing your Xml transformation? Is it through code, or XSLT?
If through code, I would define an IXmlTranslator that converts your xml into a common model:
public interface IXmlTranslator
{
XmlModel Translate(XElement element);
}
Where XmlModel is your common model:
public class XmlModel
{
// Properties
}
You'd need to specifically know which translator to use, so you'd need to pass in some sort of metadata, so we'll define a name:
public interface INamedMetadata
{
string Name { get; }
}
So an example translator could look like:
[Export(typeof(IXmlTranslator),
ExportMetadata("Name", "Null")]
public class NullXmlTranslator : IXmlTranslator
{
public XmlModel Translate(XElement element)
{
return null;
}
}
MEF will take care of projecting your metadata into an instance of INamedMetadata. Next, create a service which consumes IXmlTranslators:
[Export]
public class XmlTranslatorService
{
private readonly IEnumerable<Lazy<IXmlTranslator, INamedMetadata>> _translators;
[ImportingConstructor]
public XmlTranslatorService(IEnumerable<Lazy<IXmlTranslator, INamedMetadata>> translators)
{
_translators = translators;
}
public XmlModel Translate(string name, XElement element)
{
var translator = GetTranslator(name);
if (translator == null)
throw new ArgumentException("No translator is available to translate the target xml.");
return translator.Translate(element);
}
private IXmlTranslator GetTranslator(string name)
{
var translator = _translators
.Where(t => t.Metadata.Name.Equals(name, StringComparison.InvariantCultureIgnoreCase))
.Select(t => t.Value)
.FirstOrDefault();
return translator;
}
}
I've made the enumerable of available translators part of the constructor arguments, as it defines dependencies that are required for the service to work. MEF will take care of injecting this enumerable at composition time.
What you need to do, is either Import an instance of the XmlTranslatorService into whatever class you want to use it from, or you can initialise an instance directly from your CompositionContainer, e.g.:
var service = container.GetExportedValue<XmlTranslatorService>();
The only thing remaining would be
Creating specialised translators for each of the hotel types into the common XmlModel model class.
Serialisation of the XmlModel class into the target xml.
Hope that points you in the right direction?