Mandatory dependency in a class
If you are using a dependency injection framework then you are not using it correctly. AlbumService's constructor should have in this case another parameter that is the SqlDependencyEx. You should not be creating it by yourself. You are already injecting the other two services. Why not this one too?

And I'm wondering where you have the _masterTable parameter from? I don't see it to be passed to the AlbumService. It has only two arguments.


_listener = new SqlDependencyEx(
    connectionString: "SERVER=localhost;DATABASE=dbsample;User Id=usr;pwd=cE$6adadZ'[:3;", 
    databaseName: "KEMITEKS", 
    tableName: _masterTable);



Another thing is that the name of the SqlDependencyEx does not match the field. Why do you call it a _listener? It's very confusing.