MailSlot

A MailSlot is a type of interprocess communication that allows communication between processes both locally and over a network. The use of MailSlots is generally simpler than named pipes or sockets, but they are more limited.

Features

MailSlots function as a server-client interface. A server can create a MailSlot, and a client can write to it. Only the server can read the mailslot. A server-client interface could consist of two processes communicating locally or across a network. MailSlots do not operate over Wide Area Networks such as the internet, though. Also, MailSlots offer no confirmation that a message has been received unless it is programmed into an application. MailSlots are generally a good choice when one process must broadcast a message to multiple processes, or if a fast and very easy solution is needed.

Implementations

The most widely known implementation of the MailSlot is the Messenger service that exists in Windows NT-line of products, including Windows XP. The Messenger service is essentially a MailSlot server that waits for a message to arrive. When a message arrives it is displayed in a popup onscreen. The NET SEND command is therefore a type of MailSlot client, because it writes to specified mailslots on a network.

A number of programs also use MailSlots to communicate. Generally these are amateur chat clients and other such programs. Commercial programs usually prefer pipes or sockets. Other MailSlots include:

• MAILSLOT\Messngr - Microsoft NET SEND Protocol
• MAILSLOT\Browse - Microsoft Browser Protocol
• MAILSLOT\Alerter
• MAILSLOT\53cb31a0\UnimodemNotifyTSP
• MAILSLOT\HydraLsServer - Microsoft Terminal Services Licensing
• MAILSLOT\CheyenneDS - CA BrightStor Discovery Service

External links

• MSDN Documentation
• The Code Project Documentation