Inter-process communication with C# application

[jdy0803]

I want to have my VB6 application communicate with C# application program.
The message to communicate is simple. Here is a scenario.

VB6 APP                                            C# APP
---------------                          -----------------------
Run C# APP         "1", "2" or "3"       
Send command  ----------------> 
     Wait                                    Do work as the command
Exit from loop    <----------------        Return code
                                                       Terminate

I implemented this with Profile(ini file) but I want to do without file writing.
Which way would be desirable?

[passel]

My preference would be just to use a socket control on each side to send data back and forth.
Second might be Memory Mapped File, which doesn't actually require a file if doing non-persistent communication between the apps. For me it would be second choice because I haven't really done it, so don't have a good feel about how to go about it. But the reason I would consider it the .Net (since the 4.0 framework) includes a managed class to support Memory Mapped Files, so you don't have to resort to API calls on the .Net side of the connection.
I do a lot more socket communication though, which is why it would be my first choice. Since both VB6 and C# have a control or class to do the work, it would only take a few minutes to set up. I'm on my way out, so signing off, but I'm sure someone can point you in the right direction, or have another choice they are familiar with.

[jdy0803]

Do you mean that socket control is Microsoft Winsock Control 6.0?
If so, I know this is for TCPIP communication that interface with other PC in the LAN or WAN.
Can I use this from different process in one computer?

[jmsrickland]

Do you mean that socket control is Microsoft Winsock Control 6.0?
If so, I know this is for TCPIP communication that interface with other PC in the LAN or WAN.
Can I use this from different process in one computer?

Of course as long as both or all apps have Winsock.

[jmsrickland]

Dilittante has a ShellPipe control which works just fine as long as your C# uses StdIn, StdOut, and StdErr. Nice thing about it is you don't need to make any changes to your C# applictation

[dilettante]

As mentioned ShellPipe could work if the C# program is written as a console application, but aside from that it doesn't really apply.

Probably the only ad hoc approach that will be easy to do generally is the least common denominator: TCP or UDP. Of course you need to worry about port collisions, but for personal use you can just fish around for some available port and then hope nothing else ever tries to use it down the road. Most casual coders struggle with this though.

I can't recall whether WinForms supports DDE, but that's an often overlooked alternative with good support in VB6. Most people haven't ever used it though, so expect a round of whinging there too.

There are lots of alternatives but they all require some effort, and as usual .Net's WCF tends to throw monkey wrneches into the works to prevent interoperability.

[moonman239]

I'm just returning to the VB scene after a few years, and don't use Windows outside of school, so take what I say with a grain of salt.

I thought I read somewhere that you can have non-.NET code and .NET code in the same application. So, you can throw in some non-.NET code into the program to handle communications with your VB6 app. Then you can use .NET for the other stuff.

Hopefully, someone who's more experienced will comment on my reply.

[DataMiser]

I would probably use the TCP or UDP methods if I were doing it.

[stum]

Very interesting question you got here.

If you're working in winforms, another approach that is easy to implement is to shell a C# 's executable with a vb6 form's Textbox1.hwnd as an argument, and have C# use PostMessage API to send WM_KEYDOWN with a char to that handle.
This char can then be interpreted using the Text_Change event on the VB6 side, with a SELECT-CASE block.
This will allow your C# application to update VB6's about its progress in real-time.

If implemented well enough, and you pass a C# textbox's handle back to vb6, this can even become a two-way communication via Postmessage.

Prerequisites though are to hide the textboxes from the users on both C# and Vb6, and implemented a Switch\Select-Case blocks on each application.
looking at it, this actually sounds way more complicated than it really is, if interested i can post some code.

Another way which i found quite useful but somehow isn't very popular, and i'm probably the only person who uses it, is using Memory-writing to constants on both sides.
WriteProcessMemory API allows you to change another process's memory values - making it ideal for this situation.
It's like having a shared variable between the two application - what more can one ask.
(doing so on CONSTs is preferable as it removes the headache of playing with pointers to find the wanted memory address of your variable each time.)
If interested i can post some code on this as well.