The M-Link User Server is Isode’s main Instant Messaging and Presence server, built according to the XMPP (eXtensible Messaging and Presence Protocol) standard. It is beneficial for cases where security, reliability, and specialised features are vital, as well as large-scale public deployments.
The server boasts a wide range of features such as one-on-one chats, multi-user chats (MUC), Personal Eventing Publishing (PEP), and other XMPP services. It is used in settings with the need for heightened security and reliability and expansive public systems focused on responsiveness, performance, and scalability.
Key Features
Security
M-Link consists of extensive security features, which comprise message protection with security labels, data confidentiality via TLS, and support for various authentication methods, including SASL, Kerberos, and Strong Authentication based on X.509 PKI. It also implements boundary checks on message traffic through peering controls.
Reliability
The fundamental XMPP structure operates on a one-server-per-domain model. M-Link can manage multiple domains and facilitates assigned user administration within each domain. It supports XMPP Clustering, allowing several servers to handle a single, adaptable domain over both local and wide-area networks. To compensate for potential unreliability due to component failures—common in Mobile Unit deployments—Isode’s XMPP products include features that let users know of any potential link disruptions and offer protection.
Flexibility
M-Link is versatile as it can be adapted for public networks (such as jabber.org, one of the largest public XMPP installations) and secure environments. It can be used as a Boundary Guard, in Mobile Unit contexts, or as a gateway to IRC systems.
Archiving and Search
M-Link offers comprehensive archiving. It allows users to search chat histories and export them to XML formats, as well as providing long-term archiving in PDF/A documents.
Forms Discovery and Publishing
M-Link offers flexible Forms Discovery and Publishing (FDP), allowing it to keep a list of Topics and corresponding form templates that can be accessed and filled out by FDP-aware clients. After submission, relevant parties subscribed to the Topic are notified of the new form instance. Additional details are available on the Forms Discovery and Publishing page.
PubSub and PEP
XMPP features a Publish/Subscribe mechanism for dynamic data sharing. Personal Eventing is a key aspect that permits users to publish and share data, particularly related to extended presence information. M-Link facilitates Publish/Subscribe and PEP.
BOSH
M-Link supports BOSH (Bidirectional-Streams Over Synchronous HTTP), allowing XMPP operations over HTTP and making it possible to develop web-based XMPP clients.
Peering Controls
M-Link provides several peering controls that filter what data is transmitted to and received from other XMPP peer servers. These controls include security label checks and transformations, traffic type filtering, and message folding to protect information.
Management
Each M-Link Server maintains its own configuration, which authorised clients can access and adjust through XMPP commands. Isode offers a GUI management tool, M-Link Console (MLC), for configuration, server control, and monitoring. User accounts are stored in a Directory, with Active Directory or Isode’s M-Vault being standard options.
Administrative tools provided by Isode also support the external management of user accounts. Server and system performance monitoring can be accomplished via MLC, a web application, and SNMP, which integrates server monitoring into broader enterprise network and application oversight.
Use of Directory
M-Link uses a Directory for storing user authentication data, which is usually linked to an external enterprise directory using a standard schema already in place.