Software Deployment

DLL is the shared library concept in the wonderful world of Microsoft.

OCX is for libraries containing ActiveX controls.

CHM files is, to my knowledge, a compiled HTML help usually containing software documentation.

You cannot, cannot CANNOT do a job of ANY description in what I like to call software support (which includes packaging) without knowing basic stuff like this.

The question 'which file executes first' is one posed by an idiot, since none of those file types are executable.

May I know what did you answer?

Com/dcom is (simplified) an object model to access and use both dll's and ocx's created by Vb or other studio 6.0 languages. It has nothing to do with dll or ocx, but is a higher protocol. It was introduced with Windows 98/NT 4. The word ActiveX means that they use com/dcom for data-interchange.

The general idea was: it should not make a difference whether the code is executed local or on another computer. Hackers and other "?*@*&?" totally abused dcom, So it has been degraded into a menace of setpoints and privileges by microsoft in their attempts to make it safe.

 What remains is the difference between Dll's and ocx's (regarding VB 6.0) since they both use Com as transportmedium/protocol.

Ocx's are interfaces that you can place on a form. Like a textbox or a picturebox. They need to be driven by the form's thread and can not exist without a parentform. They can be very powerfull however. It assumes a graphical interface (not necessary) and has a special mechanism to save properties in the container (the form in which it's embedded) at designtime.

to explain Dll we have to go back a little further... One of the main improvements in windows3.x was the use of Dynamic Link Libraries (Dll). Before that every executable had to have every subroutine embedded in it's own file. Meaning they would grow and grow...... Developers already noticed that a lot of code was the same in every application, but still every application had it embedded in itself.  When a bug needed to be fixed, this meant all these applications had to be redistributed. Even now, with Internet, this would not be preferable. In those days Internet-access was not normal.

Basically: if you write several applications and they al use common code, This code is best compiled as a dll. When programming you'll hardly see any difference.

Finally I wanna conclude in this way

ocx is control exsample calander control
dll is a library 
ocx has an user iinterface but dll doesn't have
dll is plain code only
ocx have exe but dll doesn't

So Its not like which execute first or which execute Next 

Ref: Phil Wilson Articles & KumariAshwini

Thanks