Example deployment of a Tango Controls System

Example deployment of a Tango Controls System#

audience:administrators audience:developers

There are different tasks that need to be performed in a Tango Cotnrols system. One can categorise the tasks as follows:

  • Tango Host: Keep the configuration of all components in the Tango Controls system permanently stored and make it available through its API.

  • Run Tango Applications: Execute CLI programmes. e.g.tango_admin and iTango, or GUI programmes, e.g. Jive and Synoptic.

  • Run Tango Device Server(s): Execute the Tango Device Server that host Tango Devices.

  • Tango development: Implement Device Classes for Tango Devices and Tango clients.

Tip

It is possible that all of the tasks above are done on the same computer at the same time.

Hint

Tango Host, Databaseds

In order to allow clients to connect to components in a Tango Controls system, i.e. connect to Tango Tango device servers and their Tango devices, such a system needs to have at least one Tango Host. The Tango Host’s responsibility is maintain a catalog of the Tango device servers and devices that have been configured to run in the system. A Tango Host typically runs the DataBaseds device server. This device server provides the configuration information about the Tango Controls system to the device servers, devices and clients in the system. Usually clients will make use of the TANGO_HOST environment variable which contains information about the host name or IPv4 address and the port on which the Databaseds is listening. The TANGO_HOST environment variable consists of a host and a port part separated by a column:

host_name_or_IPv4_address:port, example: localhost:10000

Simple Tango Controls systems can consist of just a single computer that acts as Tango Host and runs at the same time only one or a few device servers with only a couple devices. A complex system on the other hand can easily consist of tens of thousands of device servers and theirdevices that are spread out over multiple Tango Controls systems, each with their own Tango Host but still allowing clients to connect to every device in every individual Tango Controls system.

Starter#

Having to start many device servers in a larger Tango Controls system can turn into a laborious task that takes much longer than one would want it to. Fortunately Tango comes with some batteries included and it provides the Starter device server. One can think of it as a boot-strapping device server that is able to start and stop other device servicers on the same host. Usually one puts Starter under control of one of the init systems of the OS.

Example for a very small installation#

Here we give an example for a very small installation:

  • A Tango Host. It will require a port number on that host which will be used by Databaseds for Tango requests. The hostname needs to be resolveable by all computers that run Tango software in this Tango Controls system or the host’s IP address needs to be known by the same computers. It is mandatory to start the Databaseds before any other Tango program.

  • A different computer on which a cppTango, JTango or PyTango device server will run. On the same computer can also run clients.

    • On that computer:

      • cppTango and/or JTango and/or PyTango

      • Oracle Java JRE (Java Runtime Environment) >= 1.7 to run Tango’s Java tools or JTango code.

      • Python >= 3.9 in order to run PyTango (clients or devices and device servers).

Note

An even smaller Tango Controls installation could even be a single computer. One could run everything on it. Device servers with their devices, the TangoDB and even JTango GUIs or PyTango clients.

Multiple Tango Controls systems#

Tango makes it easy to bridge the apparent boundary betweeen Tango Controls systems. This boundary exists because every individual Tango Controls system will always have its own TangoDB that manages the device servers and devices. But clients can easily cross this boundary. One just needs to address a device or attribute by its full Tango Resource Locator (TRL).

No database#

It is possible to run a device server on without a TangoDB. This can come handy for very small deployments that do not require the entire set of Tango functionality or when one wants to test something. Running a Tango system without a TangoDB is not advised.

Warning

Running a Tango system without a TangoDB can be useful for testing purposess. However, the lack of a TangoDB will remove core functionality of Tango.`

See section Running a device server without SQL database to understand how to use this configuration and what the limitations are.