Tango Data Model

audience:all

This page list and links to the different elements of the Tango Data Model.

Simplified Model

The following diagram shows the main elements of the Tango Device Model :

        classDiagram
  class cls["Device Class"]
  class dserver["Device Server"]
  click dserver href "./device.html#device-server-explanation" "Device Server documentation"
  class Pipe
  click Pipe href "./pipe.html#tango-pipe-model" "Pipe documentation"
  class Command
  click Command href "./command.html#tango-command-model" "Command documentation"
  class Attribute
  click Attribute href "./attribute.html" "Attribute documentation"
  class Event
  click Event href "./event.html" "Event documentation"
  class Device {
    domain
    family
    member
  }
  Pipe "*" <--* cls
  Command "*" <--* cls
  Attribute "*" <--* cls
  Event "*" <--* Attribute
  State --|> Attribute
  Status --|> Attribute
  Device *--> "1" cls : belongs
  dserver *--> "1..*" Device
  Device *--> "*" DeviceProperty
    

Complete Model

Here is a more complete version of the above:

        classDiagram
  direction LR
  class cls["Device Class"]
  class dserver["Device Server"]
  click dserver href "./device.html#device-server-explanation" "Device Server documentation"
  class Pipe
  click Pipe href "./pipe.html#tango-pipe-model" "Pipe documentation"
  class Command
  click Command href "./command.html#tango-command-model" "Command documentation"
  class Attribute
  click Attribute href "./attribute.html" "Attribute documentation"
  class Event
  click Event href "./event.html" "Event documentation"
  class Device {
    domain
    family
    member
  }
  Pipe "*" <--* cls
  Command "*" <--* cls
  Attribute "*" <--* cls
  Event "*" <--* Attribute
  DeviceInterfaceChangeEvent --|> Event
  ChangeEvent --|> Event
  ArchiveEvent --|> Event
  AlarmEvent --|> Event
  PeriodicEvent --|> Event
  UserEvent --|> Event
  DataReadyEvent --|> Event
  AttributeConfigurationEvent --|> Event
  State --|> Attribute
  Status --|> Attribute
  Device *--> "1" cls : belongs
  dserver *--> "1..*" Device
  Device *--> "*" DeviceProperty
  AdminDevice --|> Device
  dserver *--> "1" AdminDevice
  cls --|> DeviceImpl
  Property *--> "0..10" PropertyHistory
  AttributeProperty --|> Property
  DeviceAttributeProperty --|> AttributeProperty
  ClassAttributeProperty --|> AttributeProperty
  Device *--> "*" DeviceAttributeProperty
  DeviceProperty --|> Property
  PipeProperty --|> Property
  DevicePipeProperty --|> PipeProperty
  ClassPipeProperty --|> PipeProperty
  FreeProperty --|> Property
  ClassProperty --|> Property
  cls *--> "*" ClassProperty
  Pipe *--> "*" PipeProperty
  Attribute *--> "*" AttributeProperty
  note for Attribute "At least State and Status are always available"
  note for cls "The main class that the developer has to implement"
    

Elements

Block	Description
Device	Abstract concept defined by the TANGO device server object model; it can be a piece of hardware (an interlock bit) a collection of hardware (a screen attached to a stepper motor)a logical device (a taper) or a combination of all these (an accelerator). For more information please see the device documentation.
Device Class	From Object Oriented Programming concept, this is the main class that the developer has to implement
DeviceServer	The server (also referred as device server) is a process whose main task is to offer one or more services to one or more clients. To do this, the server has to spend most of its time in a wait loop waiting for clients to connect to it. The devices are hosted in the server process. A server is able to host several classes of devices.In short, it is a process that export devices available to accept requests). Fore more information see the device server documentation.
Property	Store a generic configuration
DeviceProperty	Device specific configuration
ClassProperty	Class specific configuration
AttributeProperty	Attribute specific configuration
ClassAttributeProperty	Attribute specific configuration at class level
DeviceAttributeProperty	Specific configuration for a specific attribute of a specific device
FreeProperty	User-defined specific configuration (for instance GUI, generic system and so on)
PropertyHistory	History of the values for a property (maximum 10 latest are stored for each property)
Attribute	See attribute.
AttributeAlias	One word which can be used to identify a specific attribute. (shortcut)
Pipe	See [pipe] (./pipe.md).
PipeProperty	Pipe specific configuration
DevicePipeProperty	Configuration of a specific pipe of a specific device
ClassPipeProperty	Configuration of a specific pipe for a specific class
Event	See event.
Command	See command.
ChangeEvent	It is a type of event that gets fired when the associated attribute changes its value according to its configuration specified in system specific attribute properties (abs_change and rel_change). See events.
ArchiveEvent	It is a type of event that gets fired when the associated attribute should be archived according to its configuration specified in system specific attribute properties (archive_abs_change, archive_rel_change and archive_period). See events.
UserEvent	It is a type of event that gets fired when the device server programmer wants to. See events.
PeriodicEvent	It is a type of event that gets fired at a fixed periodic interval. See events.
DataReadyEvent	It is a type of event that gets fired to inform a client that it is now possible to read an attribute. See events.
AttributeConfigurationEvent	It is a type of event that gets fired if the attribute configuration is changed. See events.
DeviceInterfaceChangeEvent	It is a type of event that gets fired when the device interface changes. See events.
DeviceImpl	Base implementation of every class that will become a device.
State	The device state is a number which reflects the availability of the device.
Status	The state of the device as a formatted ascii string
AdminDevice	Special type of Device dedicated to creating and managing the devices, i.e. restart device, kill the device server (the process), creating polling mechanism and so on

Attributes

Block	Attribute	Description
Device	name	Correspond to “Domain/family/member”
	alias	A word that you can use to access the device, like a shortcut. Device name alias(es) must also be unique within a control system. There is no predefined syntax for device name alias.
	domain	Each device has a unique name in the control system. Within Tango, a four field name space has been adopted consisting of[//FACILITY/]DOMAIN/CLASS/MEMBERFacility refers to the control system instance, domain refers to the sub-system, class the class and member the instance of the device.
	family
	member
	version	It correspond to the version of base device implementation class (for backward compatibility). It is used to know how to communicate with this device and what features are supported.
	class	Name of the class corresponding to the Device
	ior	Orb Identifier used to connect with the device
	host	Where the device is running
	pid	Id of the specific process
	exported	Means that the device is available to accept request
DeviceServer	Facility	Represent the host where the device server instance (aka process) lives
Attribute	alias	A shortcut that you can use to access the attribute (in the Database there is a specific table)

Relations

Left Block	Right Block	Multiplicity	Description
Device	Device Class	1	Every device belongs to a Tango Device class
Attribute	ClassAttributeProperty	0..*	An attribute can have more than one class attribute property associated
Attribute	Event	0..*	An attribute can have more than one event associated
Device	DeviceAttributeProperty	0..*	A device can have more than one Device Attribute Property associated
Device	DeviceProperty	0..*	A device can have more than one Device Property associated
Device	Attribute	2..*	A Device can have more than one Attribute associated via reference
DeviceServer	AdminDevice	1	Every device server is exporting one admin device
DeviceServer	Device	1..*	Every Device server has many devices inside itself
Pipe	PipeProperty	0..*	A pipe can have more than one Pipe Property associated
Property	PropertyHistory	0..10	A Property can have more than one Property history associated (this will maintain the history of the change for the property)
Device Class	Attribute	2..*	A Device Class can have more than one Attribute associated
Device Class	ClassProperty	0..*	A Device Class can have more than one Class Property associated
Device Class	Command	2..*	A Device Class can have more than one Command associated
Device Class	Pipe	0..*	A Device Class can have more than one Pipe associated

Rationale

Please refer to the Tango Device Model .