Dot Net Interview Questions

How do we create DCOM object in VB6?

Using the CreateObject method you can create a DCOM object. You have to put the server name in the registry.

How many types of Transactions are there in COM+.NET?

There are 5 transactions types that can be used with COM+. whenever an object is registered with COM+ it has to abide either to these 5 transaction types.

Disabled: There is no transaction. COM+ does not provide transaction support for this component.

Not Supported: Component does not support transactions. Hence even if the calling in the hierarchy is transaction enabled this component will not participate in the transaction

Supported: Components with transaction type support will be a part of the transaction. This will be only if the calling component has an active transaction. If the calling component is not transaction enabled this component will not start a new transaction.

Required: Components with this attribute require a transaction i.e. either the calling should have a transaction in place else this component will start a new transaction.

Required New: Components enabled with this transaction type always require a new transaction. Components with required new transaction type intantiate a new transaction for themselves every time.

How do you do object pooling in .NET?

COM+ reduces overhead by creating object from scratch. So in COM+ when object is activated its activated from pool and when its deactivated its pushed back to the pool. Object pooling is configures by using the "ObjectPoolingAttribute" to the class.

What are the types of compatability in VB6?

There are three possible project compatability settings
No Compatbility
with this setting, new clss ID's,new interface ID's and a new type library ID will be generated by VB each time the ActiveX component project is compiled. This will cause any compiled client components to fail and report a missing reference to the 'VB ActiveX Test Component' when a client project is loaded in the VB IDE

Project Compatability
With this setting, VB will generate new interface ID's for classes whose interfaces have changed,but will not change the class ID's or the type library ID. This will still cause any compiled client components to fail but will not report a missing reference to the 'VB ActiveX Test Component' when a client project is loaded in the VB IDE. Recompilation of client components will restore them to working order again.

Binary Compatability
VB makes it possible to extend an existing class or interface by adding new methods and properties etc. and yet still retain binary compatibility. It can do this, because it silently creates a new interface ID for the extended interface and adds registration code to register the original interface ID but with a new Forward key containing the valueof this new interface ID. COM will then substitute calls having the old ID with the new ID and hence applications built against the old interface will continue to work.

What is equivalent for regsvr32 exe in .NET?

Regasm