MailSlot

[trancexx]

This way of communication between processes very much resemble to the communication we do with our mail accounts. I would guess (smartly, no doubt) that was the key factor used for naming the functions when they were created.

Information about mailslots can be found on microsoft's site, link. Summary could be that datagrams are used for communication and it's one-way and asynchronous.

Attached zip file contains MailSlot.au3, AutoIt's implementation of these functions.

Also there would be two scripts in there MailSlot_Sender.au3 and MailSlot_Reciever.au3. Both scripts are demos of the mailslot mechanism. Start both and use former to send mails to latter.

Examples are basic and should show what's this about.

MailSlot.zip

Available functions are alphabetically:

• _MailSlotCheckForNextMessage
• _MailSlotClose
• _MailSlotCreate
• _MailSlotGetMessageCount
• _MailSlotGetTimeout
• _MailSlotSetTimeout
• _MailSlotRead
• _MailSlotWrite

edit:

New attachment. _MailSlotGetTimeout() function added to MailSlot.au3.

Edited December 15, 2009 by trancexx

[martin]

This is great trancexx, but one of the most interesting things that you didn't mention is that this works across a network.

There's another good link here which explains some of this. If you use this over a network then pay attention to the caveats in that link.

Thanks for this thread.

Edited December 12, 2009 by martin

[Michel Claveau]

Hi, Trancexx !

I had played with Mailslot, in past.

Your functions are better than my "hardcoded" tests.

(your) mailslot is compatible with the waitfor command-line from Windows, or my others libs (i.e. in Python) (I tested the two cases).

Thanks (and sorry for my bad english).

Two little things:

- read a Mailslot without data give, on my 7, a "Autoit memory allocation error".

- your functions are OK with ASCII messages, but, when I tested messages in UTF-8 or CP1252, with diacritics, there are some worries (not very important)

@-salutations

--

Michel Claveau

Edited December 13, 2009 by Michel Claveau

[trancexx]

Hi, Trancexx !

I had played with Mailslot, in past.

Your functions are better than my "hardcoded" tests.

(your) mailslot is compatible with the waitfor command-line from Windows, or my others libs (i.e. in Python) (I tested the two cases).

Thanks (and sorry for my bad english).

Two little things:

- read a Mailslot without data give, on my 7, a "Autoit memory allocation error".

- your functions are OK with ASCII messages, but, when I tested messages in UTF-8 or CP1252, with diacritics, there are some worries (not very important)

@-salutations

--

Michel Claveau

No, thank you.

"Autoit memory allocation error" is my mistake. I've located a mistake and will correct it... eventually. The problem is _MailSlotCheckForNextMessage() function. Corrected would be:

If $aCall[3] = -1 Or Not $aCall[4] Then
        Return 0
    Else
        Return $aCall[3]
    EndIf

instead of current:

If $aCall[3] = -1 Then
        Return 0
    Else
        Return $aCall[3]
    EndIf

Same thing can be done with _MailSlotGetMassageCount(), but it shouldn't strictly be necessary.

Unicode problem is likely not related to these functions.

You can always read binary and interpret it the way you like it, as I'm sure you are aware of.

[The Kandie Man]

This is great. I found only one nitpicking issue:

_MailSlotGetMassageCount()

Perhaps you meant:

_MailSlotGetMessageCount()

Just a typo, good work though.

- The Kandie Man ;-)

[trancexx]

lol

[trancexx]

There. New and improved scripts posted.

I added one new function while at it. It's _MailSlotSetTimeout() to change time-out for reading at any time.

Thanks for the heads up. Much appreciated.

[Michel Claveau]

Hi, all !

Here a very simplist example, who show dialog/drive (with) a Batch.

#include "MailSlot.au3"

writebat()

run("C:\MStest.bat")

Sleep(2000)

Global $sMailSlotName = "\\.\MailSlot\waitfor.exe\SIGNAL"

_SendMail($sMailSlotName,"1")

Sleep(2000)

_SendMail($sMailSlotName,"2")

Sleep(4000)

_SendMail($sMailSlotName,"3")

Exit

Func _SendMail($sMailSlotName,$sDataToSend)

_MailSlotWrite($sMailSlotName, $sDataToSend, 1)

Switch @error

Case 1

MsgBox(48, "MailSlot error", "Account that you try to send to likely doesn't exist!")

Case 2

MsgBox(48, "MailSlot error", "Message is blocked!")

Case 3

MsgBox(48, "MailSlot error", "Message is send but there is an open handle left." & @CRLF & "That could lead to possible errors in future")

Case 4

MsgBox(48, "MailSlot error", "All is fucked up!" & @CRLF & "Try debugging MailSlot.au3 functions. Thanks.")

Case Else

;MsgBox(64, "MailSlot", "Sucessfully sent!")

EndSwitch

EndFunc ;==>_SendMail

Func writebat()

$b=""

$b &= "@echo off " & @CRLF

$b &= "echo Etape_1" & @CRLF

$b &= "waitfor /T 60 SIGNAL"& @CRLF

$b &= "echo Etape_2" & @CRLF

$b &= "waitfor /T 60 SIGNAL"& @CRLF

$b &= "echo Etape_3" & @CRLF

$b &= "waitfor /T 60 SIGNAL"& @CRLF

$b &= "echo Etape_4" & @CRLF

$b &= "pause Ended" & @CRLF

$f=FileOpen("C:\MStest.bat",2)

FileWrite($f,$

FileClose($f)

EndFunc

MStest.au3

Edited December 13, 2009 by Michel Claveau

[Melba23]

trancexx,

Well up to your usual standard. Thank you for sharing.

M23

[Digisoul]

Great Script Trancexx , this is the most reliable I.P.C method then others.

[martin]

Hi, all !

Here a very simplist example, who show dialog/drive (with) a Batch.

I think that got a bit messed up! I think this is what you tried to post.

Code removed now that Michel has corrected his post.

I'll delete this post when you've corrected yours.

I decided not to delete this post or the next one makes no sense.

Edited December 13, 2009 by martin

[Michel Claveau]

Re !

Thanks, Martin.

I had no found how to edit a message with some code.

I am not made for modern-english's methods

[dmob]

Congratulations to you!!!

I have successfully implemented your UDF across a network, and you Sir,

have enabled me to solve a problem I've had for a while now and you've

made me a very happy man!

Thanks for your work, and for sharing.

Five stars from me

Edited December 14, 2009 by dmob

[JRSmile]

hi trancexx,

you saved my ass

i just thought about fifo buffering tcp packets and crawled the forum a bit, found the mmap udf but this wasn't the right thing

now with your udf i can go on with my project thank you very much.

Best regarrds,

JR.

[trancexx]

I think it would be necessary to have one more function _MailSlotGetTimeout().

That way you could read current time-out, change it to new, read the message, restore the old time-out.

Yeah, that's missing.

[JScript]

@trancexx

Hello,

I see that your UDF will solve my problem with function TCPConnect() it takes on average 20 seconds to return control to the program if no connection found (...) Send Broadcast messages (TCP does not support broadcast, UDP does, but not using NAT), simple to implement, there is no doubt that it is better than the TCC/UDP (at least for me).

Already solved 90% of my problems, but I have left some questions:

1 - Records smaller than 425 bytes?!? Why? No way around?

2 - Transferring files (binaries)?

Thank you for your attention.

Edited March 15, 2011 by jscript

[JScript]

Wow! I had never paid attention to the item "NamedPipes Management " in the AutoIt help file!

And using NamedPipes we can transfer more than the 425 bytes of the mailslot...

Edit: http://www.codeproject.com/KB/threads/Win32IPC.aspx

@trancexx, you could create an example of using "NamedPipes" the same way that the mailslot?

Edited March 16, 2011 by jscript

[trancexx]

@trancexx

Hello,

I see that your UDF will solve my problem with function TCPConnect() it takes on average 20 seconds to return control to the program if no connection found (...) Send Broadcast messages (TCP does not support broadcast, UDP does, but not using NAT), simple to implement, there is no doubt that it is better than the TCC/UDP (at least for me).

Already solved 90% of my problems, but I have left some questions:

1 - Records smaller than 425 bytes?!? Why? No way around?

2 - Transferring files (binaries)?

Thank you for your attention.

Well hello there.

There shouldn't be 425 byte limit. You are probably doing something wrong, maybe sending/reading as string with null terminator as 425th character.

You can transfer binary data, there is a flag for that, default even. Don't limit your self on my examples, they are there just to show the main principle of communication.

Edited March 16, 2011 by trancexx

[JScript]

Well hello there.

There shouldn't be 425 byte limit. You are probably doing something wrong, maybe sending/reading as string with null terminator as 425th character.

You can transfer binary data, there is a flag for that, default even. Don't limit your self on my examples, they are there just to show the main principle of communication.

"...Mailslot messages can be of around 400 bytes only.", please check this link: http://www.codeproject.com/KB/threads/Win32IPC.aspx

"...cannot be larger than 424 bytes when sent between computers.", and this: http://msdn.microsoft.com/en-us/library/aa365130%28v=vs.85%29.aspx

Edited March 16, 2011 by jscript

[Melba23]

jscript,

If you look at the link martin provided in post #2, you read this:

"Boring technical note from Microsoft

Records smaller than 425 bytes are sent using datagrams. Records larger than 426 bytes are sent using a connection-oriented transfer over an SMB session. Connection-oriented transfers are limited to one-to-one communication from one client to one server. Note that Windows does not support records that are 425 or 426 bytes."

Certainly I have never had any trouble sending more than 425 bytes to multiple receiver scripts using the mailslot.

M23