Basic Interview Questions
type of multi-threading does VB6 implement?
Apartment model threading
How to register a component?
Compiling the component, running REGSVR32 MyDLL.dll
What is Database Connection pooling (relative to MTS)
This allows MTS to reuse database connections. Database connections are
put to "sleep" As opposed to being created and destroyed and are
activated upon request.
What is the tool used to configure the port range and protocols for DCOM
What is a Type Library and what is it's purpose ?
The type library may represent another Visual Basic project, or any other
executable component that exposes a type library.
Visual Basic creates type library information for the classes you create,
provides type libraries for the objects it includes, and lets you access the
type libraries provided by other applications.
What are binary and project compatibility?
Visual Basic?s Version Compatibility feature is a way of enhancing your
components while maintaining backward compatibility with programs that were
compiled using earlier versions. The Version Compatibility box, located on the
Component tab of the Project Properties dialog box, contains three options:
Each time you compile the component, new type library information is generated,
including new class IDs and new interface IDs. There is no relation between
versions of a component, and programs compiled to use one version cannot use
Each time you compile the component the type library identifier is kept, so
that your test projects can maintain their references to the component project.
All class IDs from the previous version are maintained; interface IDs are
changed only for classes that are no longer binary-compatible with their earlier
counterparts. Note This is a change in Project Compatibility from Visual Basic
5.0, where all class IDs and interface IDs in the project changed if any one
class was no longer binary-compatible.
Important For the purpose of releasing compatible versions of a component,
Project Compatibility is the same as No Compatibility.
When you compile the project, if any binary-incompatible changes are
detected you will be presented with a warning dialog. If you choose to accept
the warning, the component will retain the type library identifier and the class
IDs. Interface IDs are changed only for classes that are no longer
binary-compatible. This is the same behavior as Project Compatibility.
If, however, you choose to ignore the warning, the component will also maintain
the interface IDs. This option is only available when the compiler determines
that the change was in the procedure ID or signature of a method.
Note:: When people talk about Version Compatibility, they?re usually
referring to Binary Compatibility.
How to set a shortcut key for label?
object.KeyLabel(keycode) [= string]
You would probably create the menu item as follows:
.Add "keyFile", , , "E&xit", , vbAltMask + vbCtrlMask,
The default key label for vbKeyEnd is "End". Thus, the shortcut string
will be created by default as "Ctrl+Alt+End".
Name the four different cursor and locking types in ADO and describe them
The cursor types are listed from least to most resource intensive.
Forward Only - Fastest, can only move forward in recordset
Static - Can move to any record in the recordset. Data is static and never
KeySet - Changes are detectable, records that are deleted by other users are
unavailable, and records created by other users are not detected Dynamic - All
changes are visible.
LockPessimistic - Locks the row once after any edits occur.
LockOptimistic - Locks the row only when Update is called.
LockBatchOptimistic - Allows Batch Updates.
LockReadOnly - Read only. Cannot alter the data.
Name the different compatibility types when creating a COM component.
No Compatibility - New GUID (Globally Unique Identifier) created, references
from other components will not work Project Compatibility - Default for a new
component <Not as critical to mention this one>
Binary Compatibility - GUID does not change references from other components
Why is it important to use source control software for source code?
Modification history. Code ownership: Multiple people cannot modify the same
code at the same time.
List the ADO objects?
Connection - Connects to a data source; contains the Errors collection
Command - Executes commands to the data source. The only object that can accept
parameters for a stored procedure Recordset - The set of data returned from the
Under the ADO Command Object, The Parameters collection. collection is
responsible for input to stored procedures?
What two methods are called from the ObjectContext object to inform MTS that
the transaction was successful or unsuccessful?
SetComplete and SetAbort.