OpenAMQ is a fast, stable, free implementation of the AMQP (www.amqp.org) messaging protocol. It gives applications high-performance messaging (delivery of opaque data) across loosely connected networks. It is capable of handling up to 600k messages per second depending on the hardware, with a latency around 300 microseconds. It is multithreaded and supports C/C++ and Java on Linux, AIX, Solaris, OS/X, Windows, and OpenVMS.
The 0MQ lightweight messaging kernel is a library which extends the standard socket interfaces with features traditionally provided by specialized messaging middleware products. 0MQ sockets provide an abstraction of asynchronous message queues, multiple messaging patterns, message filtering (subscriptions), seamless access to multiple transport protocols, and more.
PICI-NMS is an object oriented middleware which makes possible sending messages in a networked environment or on a single host between applications using the library provided. The supported message sending mechanism is "publish/subscribe" and this is backed up by a very easy-to-use and intuitive C++ API which hides the underlying socket interface to make the message sending as transparent to the client as possible.
The SMS Server Tools 3 is a SMS gateway that can send and receive short messages through GSM modems and mobile phones. Messages are sent by simply storing text files into a special spool directory. It also stores received messages into another directory as text files. Binary messages including Unicode text and ring tones are also supported, and it is possible to send WAP Push and system messages. The program can run scripts after events like the reception of a message, successful sending, and when the program detects a problem.
Synovel Collabsuite provides email, calendaring, and instant messaging solution for enterprises. It consists of a Linux email server with calendar and IM, a Web-based administration panel, a desktop client suite that runs on Windows and Linux, and AJAX-based Web mail access. It uses open standards for communications: IMAP, POP, and SMTP for email, CalDav for calendaring, and Jabber for IM.
Apache Qpid is a messaging broker that implements the latest AMQP specification, providing transaction management, queuing, distribution, security, management, clustering, federation, heterogeneous multi-platform support, and much more. It is extremely fast and aims to be 100% AMQP Compliant.
Collage is a cross-platform C++ library for building heterogenous, distributed applications. Among other things, it is the cluster backend for the Equalizer parallel rendering framework. It provides an abstraction of different network connections, peer-to-peer messaging, node discovery, synchronization, and high-performance, object-oriented, versioned data distribution. It is designed for low-overhead multi-threaded execution, which allows applications to easily exploit multi-core architectures.