Many a times there are requirement to share
a value/property between multiple Domain Service calls. Problem is on each call
we have new instance of the DomainService. i.e. Each time a client calls into
the DomainService endpoint, the RIA hosting layer uses the singleton
DomainService.Factory to create a new instance of the requested DomainService type. The default IDomainServiceFactory implementation expects a DomainService type to provide a
parameter-less constructor. So there is no possibility of injecting the shared property during the creation of Domain Service. In my case scenario was to share
a unique instance of the following to multiple Domain Service call –
SerializationService and SunixAuthService
See below the approach –
1.
Created my own
custom DomainServiceFactory -
public class SunixDomainServiceProvider : IDomainServiceFactory
{
private
SerializationService _serializationService;
private
SunixAuthService _sunixAuthService;
public SunixDomainServiceProvider()
{
_serializationService = new SerializationService();
_sunixAuthService = new SunixAuthService();
}
public DomainService CreateDomainService(Type domainServiceType, DomainServiceContext
context)
{
DomainService
domainService;
if
(typeof(CustomDomainService)
== domainServiceType)
{
domainService = new CustomDomainService(_serializationService,
_sunixAuthService);
}
else
{
domainService = (DomainService)Activator.CreateInstance(domainServiceType);
}
domainService.Initialize(context);
return
domainService;
}
public void ReleaseDomainService(DomainService
domainService)
{
domainService.Dispose();
}
}
2. Registed
the Factory in the Global.asax
Now that we have a custom factory, we’ll
have to make sure it gets used to instantiate our DomainService. The easiest
way to do this is to add a Global.asax file to our web site and bootstrap the
factory there.
protected void
Application_Start(object sender, EventArgs e)
{
DomainService.Factory
= new SunixDomainServiceProvider();
}
3. Now
change your DomainService ctor to accept these values –
[EnableClientAccess()]
public class CustomDomainService : LinqToEntitiesDomainService<EntityTestDBEntities>
{
public
CustomDomainService(ISerializationService
sss, ISunixAuthService acs)
{
}
public IQueryable<School>
GetSchools()
{
return
this.ObjectContext.Schools;
}
}
Now if you Test the Service you find the
constructor of the SunixDomainServiceProvider is hitting only once irrespective
of how many calls clients are making.
public
SunixDomainServiceProvider()
{
_serializationService = new SerializationService();
_sunixAuthService = new SunixAuthService();
}
Conclusion: If you want to
maintain a instance of some property/value then the CustomDomainServicePactory
is appropriate place and can’t be achieved at the DomainService itself.
