Using Global Variable for Inter Program Communication

[Panthaur]

I am looking to create an easy, simple inter-communiction system between 2 applications.

I have a c++ console app (technically not a dos app because it does require use of a dll) that I am writing a menu application for, and I want to be able to send messages back and forth between the 2 programs. I was thinking of trying to make use of global variables to achieve this communication, or possible a text file on the users hard drive.

Does anyone have any suggestions on:
a) Will this approach work?
b) How to achieve this communication in another way?

Thanks for the input!

Panthaur

 

[cgfiend]

I definitely wouldn't use the registry for constant writing of data (i.e. talking back and forth between apps). The registry is designed for storage and retrieval of app config data, not constant reads/writes---although it's possible to do so. What I would do is investigate the SendMessage API. Look for samples on the net. One of my favorite sites for VB samples is

http://www.mvps.org/vbnet.

A SendMessage sample is too lengthy to post here, but there are plenty out there if you use a search engine and look up "VB SendMessage". That's what SendMessage is for, talking back and for between apps. I just recently tied two VB apps together using SendMessage. Works great and it's fast.

 

[Hypetia]

Microsoft knowledge base article 176058 explains how to pass string data between two applications.

http://support.microsoft.com/defaul...port/kb/articles/Q176/0/58.asp&NoWebContent=1

I also discussed a similar solution in my previous post but the problem is Panthaur cannot use SendMessage between two application as atleast one of the application is a console application.

 

[strongm]

Hence my suggestion concerning the use of named pipes or mailslots...

 

[Panthaur]

I'm actually going to try and implement sendmessage this weekend. I figure that if I am using API's to send data to the registry from my console app, I should be able to use the API calls for sendmessage, and I don't have to worry about corrupting an already "shaky" registry.

Panthaur

 

[strongm]

The problem is that SendMessage requires the hWnd of a target window that has a windows message handling queue. What Hypetia was getting at is that console applications (normally) don't have that...

 

[Panthaur]

Well, I guess I am stuck with the registry method then... I don't have much of a choice.

Thanks for all the help and suggestions,
Panthaur

 

[strongm]

So create an invisible window for the console app that'll handle the message queue, or use a named pipe or a mailslot. Or even a shared COM object...

 

[Ladyhawk]

I am wanting to do something similar.. and I think my my purpose using a named pip is the way to go. If anyone is interested I found a good link on named pipes.

http://support.microsoft.com/defaul...port/kb/articles/Q177/6/96.ASP&NoWebContent=1

Ladyhawk.
** ASP/VB/Java Programmer **

 

[Panthaur]

I wouldn't know how to create an invisible window in C to handle the messages. I am most a VB programmer, and I was lucky to get the registry method working in C++. I know the basics of C++, but when I have to get into using the windows API's, I just don't know enough yet, an I have to get this project done, so I don't have the time to go thru a c++ learning curve.

All in all, the registry method is working GREAT. I have done a lot of testing, including writing 2 apps to communicate back and forth for 14 days testing my registry writing and reading method, no crashes or slowdown in the test computer. I increased the writing and reading to 5ms instead of the 50ms that I have programmed into the actual app, and have still had stellar results.

Take care,
Panthaur