Chat Programs

Online chat software includes any program which transmits short text messages between the sender and receiver. These realtime keyboard-to-keyboard messages create an environment similar to a spoken conversation. A chat session may involve one-to-one communication or group meetings. These programs are valuable for quick question/answer interactions where immediate replies are important. Timestamped conversation history is typically saved for future reference.

Chat programs are one of the least network-intensive types of communication programs, so they are a good candidate as low impact services on a mesh network. Many chat programs also offer file sharing, which allows you to get two functions within a single program. The following list is not comprehensive or complete but represents a sample of the types of chat programs that might be available for you to use as services on your mesh network. Only programs with open source licenses were included in this list, although commercial chat software can also be used.

MeshChat

MeshChat has become the primary chat service for AREDN™ networks because it was written specifically for mesh communication. Users access MeshChat via web browser, and the service runs on the mesh node itself or on a LAN-connected Raspberry Pi computer. After logging in by entering a call sign, send a message by typing into a text box and clicking the Submit button. The list of active users is displayed, and every message is visible to all participants on the chat service. Multiple Zones and Channels are supported for categorizing and separating message traffic.

The message database is stored on every device where MeshChat is running. Nodes may have intermittent network connectivity, but as long as at least one node is available the MeshChat database remains intact. Once nodes come online they immediately catch up by retrieving a full copy of the message database. If any new messages are found, they are appended to the local message database.

In addition to the keyboard-to-keyboard chat feature, MeshChat also allows files to be shared between nodes. Files may be uploaded from or downloaded to the user’s computer at any time. If MeshChat is running on a radio node then the file storage is limited to 500 kb, but if running on an external computer the file storage is limited only by the size of the disk that is allocated for MeshChat files.

MeshChat Action Scripts also provide for functional extensions, such as sending messages to an SMS gateway for external distribution. It is also possible for action scripts to periodically save the message database for archive purposes or integration with external tools. For additional information about MeshChat, visit this link: MeshChat

MeshChat Web Interface

Internet Relay Chat

Several implementations of Internet Relay Chat are available, either as open source software or in proprietary versions. The Internet Relay Chat Daemon (IRCd) is a server program that listens for connections from IRC client programs and brokers the communication between the connected clients. With this client-server architecture, the IRC server must be available on a network link with sufficient bandwidth in order for the clients to function.

A wide variety of features and functions are available with these and similar chat programs, including various zones, channel types, and user roles. For additional information about IRC services, visit these links: IRC Servers and IRC Clients

IRC in KiwiChat Web Interface

Jabber/XMPP

Originally known as Jabber, XMPP servers have been around for a long time but are fully compliant with modern messaging standards thanks to a large community of developers worldwide. These servers provide one-to-one messaging as well as group chat sessions. User lists have activity and presence indicators, and chat history can be archived for later use. There are dozens of feature modules available for XMPP servers which can extend the functionality as needed.

Two of the most popular XMPP servers are eJabberd and Prosody, but there are many others. For additional information about these services, visit the following links: eJabberd and Prosody

Prosody XMPP Interface

Let’s Chat

Let’s Chat is an open source messaging service for small teams. It provides one-to-one communication between XMPP users as well as group messaging and @mentions in a variety of chat rooms. Searchable conversation history is available, in addition to text and image pasting, user activity notifications, and file uploads. User self-registration is configurable on the server. For additional information about Let’s Chat, visit this link: Let’s Chat

Let's Chat Interface

Mattermost

The Mattermost Team Edition is an open source platform that supports mobile and desktop messaging apps. It provides one-to-one and group messaging, file sharing, and message history with search capabilities. It is often described as an open source alternative to the commercial Slack communication tool.

Mattermost supports @mentions, and channels are available for organizing conversations which can be topic-based, group-based, or event-based. Notifications indicate user presence and activity. File sharing is provided for PDF and text files, as well as audio, video, and image files. For additional information about Mattermost, visit this link: Mattermost

Mattermost Interface

Matrix - Synapse

Synapse is the “homeserver” implementation of the Matrix communication platform. As with a traditional client-server architecture, every user runs a Matrix client that connects to a Synapse server which stores the personal chat history and user account information. However, these servers communicate with each other on the network, which creates a distributed content architecture that minimizes single points of failure.

Matrix services can provide one-to-one communication channels as well as group chats in a variety of rooms. User presence and typing notifications are supported, as well as chat history and read receipts. Although the Matrix platform is intended to provide end-to-end encryption, it can be run without cryptographic signing. Matrix can also integrate with IRC services, as well as VoIP and video conferencing solutions via WebRTC. For additional information about Matrix-Synapse, visit these links: Matrix Home and Synapse

Matrix Chat Interface

Example Chat Service Comparison

Platform abbreviations:
win=MS Windows, mac=Apple, lin=Linux, rpi=Raspberry Pi
Program Architecture Network Load Age Platform Effort
MeshChat mesh aware small new node/rpi easy
IRCd server client-server small old lin/mac/rpi/win medium
Jabber/XMPP client-server small old lin/mac/rpi/win medium
Let’s Chat client-server small new lin/mac/rpi/win medium
Mattermost client-server medium new linux expert
Matrix distributed medium new linux/mac expert