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JMRI Code: Network Access

This page describes various forms of network access available in JMRI. More capabilities are added all the time, so please check with the user group for up-to-date information.

Methods of Network Access

JMRI interacts with networks in two basic forms: downstream connections and upstream connections.

A downstream connection allows JMRI to connect to a layout via a network for operations and control. This uses a network connection to do the same kinds of things that are often done via serial RS232 and USB links. In the client-server architecture, JMRI is usually one of potentially many clients connecting to a server in this case.

An upstream connection allows other devices to command JMRI over a network connection. In this case, the network connection allows other devices and/or programs to do things that are normally done via scripts and the graphical user interface. In the client-server architecture, JMRI is usually a server with one or more clients connecting to it in this case.

Note that the JMRI JSON and Web servers can be used by other layout-connected devices such that both the JMRI application and the other device can be simultaneously "downstream" and "upstream" of each other for specific aspects of layout control. In this case, although JMRI is functionally the server (in a client-server architectural sense), it is receiving layout updates from the client device.

In the rest of this page, we provide links to the various examples of those two general areas.

Downstream (networked layout hardware) connections

Upstream (networked JMRI operations) connections

See also the DNS-SD page for more information on Zeroconf/Bonjour/"DNS Service Discovery" networking.

Search "man dns-sd" for more information on the dns-sd debugging command-line tool.