Equeue, now a part of Ocamlnet, contains a generic implementation of queues of events of any type, and a specific implementation of queues of file descriptor events.

The generic module allows to associate an event queue with an event source, and one or several event handlers. The event source generates new events that are triggered from the outer world. The handlers consume events, but it is allowed that handlers also generate events.

The module for file descriptor events already defines an event source; this source watches registered file descriptors and produces events if a descriptor wants to deliver data, or if a descriptor is ready to accept data. As in the generic module, the handlers consume the events.

The main application of these modules are implementations of protocol stacks which can cooperate with each other. Currently, my RPC implementation uses Equeue. There is already a version of Netclient basing on Equeue. Included in the Equeue distribution there are modules to invoke Unix commands and to handle pipelines to them in an event-based manner.