A Mailslot is a one-way

interprocess communication In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categoriz ...

mechanism, available on the Microsoft Windows operating system, that allows communication between processes both locally and over a

network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

. The use of Mailslots is generally simpler than named pipes or sockets when a relatively small number of relatively short messages are expected to be transmitted, such as for example infrequent state-change messages, or as part of a peer-discovery protocol. The Mailslot mechanism allows for short message broadcasts ("datagrams") to all listening computers across a given network domain.

Features

Mailslots function as a server-client interface. A

server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...

can create a Mailslot, and a

client Client(s) or The Client may refer to: * Client (business) * Client (computing), hardware or software that accesses a remote service on another computer * Customer or client, a recipient of goods or services in return for monetary or other valuabl ...

can write to it by name. Only the server can read the mailslot, as such mailslots represent a one-way communication mechanism. A server-client interface could consist of two processes communicating locally or across a network. Mailslots operate over the RPC protocol and work across all computers in the same network domain. Mailslots offer no confirmation that a message has been received. Mailslots are generally a good choice when one client process must broadcast a message to multiple server processes.

Uses

The most widely known use of the Mailslot IPC mechanism is the Windows Messenger service that is part of the

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-line of products, including

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. The Messenger Service, not to be confused with the MSN Messenger internet chat 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

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...

s or sockets. Mailslots are implemented as files in a mailslot file system (MSFS). Examples of 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

Mailslots (MSDN Documentation)

Using Mailslots for Interprocess Communication

Using a Mailslot to read/write data over a network
Inter-process communication {{comp-sci-stub