Question

Using Delphi XE to build a relatively straightforward database app using Datasnap.

Since some security in my application is handled at the database level, I need to pass a user’s SQL credentials from my client app to my Datasnap server.

(I’m trying to make the Datasnap server stateless if possible, so recognise that I will have to do this for every call.)

I’m using ClientDatasets (CDS) on the client side so I could use OnBeforeGetRecords to pass the data in the OwnerData OleVariant from the CDS on the client to the corresponding TDataSetProvider on the server. But that means every single CDS on every data module has to have an event that does this, which seems messy and unwieldy. I can’t help feeling there must be a way to pass messages to the server at a higher level than that.

What I’d really like is something like this at the DSServerClass level on the server side:

Procedure TMyServerContainer.MyServerClassCreateInstance(DSCreateInstanceEventObject: TDSCreateInstanceEventObject); 
begin 
// Server detects request for data from client app 
fUsername := GetUsernameFromClientSomehow; 
fPassword := GetPasswordFromClientSomehow;

// create data modules and initialise
MyDataModule := TMyDataModule.Create(nil); 
MyDataModule.InitialiseWithSQLCredentials(fUsername, fPassword); 
DSCreateInstanceEventObject.ServerClassInstance := MyDataModule; 
End;

Could the Authentication Manager component help me here? Any other ideas? Or am I stuck with OnBeforeGetRecords?

Many thanks.

Answer 1

You can use the SQL credentials as UserName and Password for connecting to the DataSnap server. These values can be verified in the Authentication Manager and/or simply forwarded to the underlying SQLConnection component for connecting to the SQL server.