Object Classes

While functions represent the overall purpose a device fulfils, the class represents general type of the device, irrespective of the manufacturer of said device.

Thus, for the storage function, it has the classes: dewar, cryostat, gas bladder, compressed gas storage and gas bundle. For the indicator function, the classes are: pressure sensor, thermometer and contamination sensor. Functions describe the overall purpose of the device, while the class groups all devices of the same type, regardless of the specific model and manufacturer.

Between the GAM_OBJECTCLASS and GAM_FUNCTION tables there is a many to one relationship with total participation, each function has one or more classes and each class must belong to a function.

Between the GAM_OBJECTCLASS and GAM_DISPLAYFORMAT tables there are 5 optional many-to-one relationships. A display format can be applied to multiple classes, and each can have up to 5 display formats.

Classes are further divided into object types, and therefore between the GAM_OBJECTCLASS and GAM_OBJECTTYPE there is a one to many relationship with total participation, each class has one or more object types.

Measurements and classes

The class of an object is important as it defines the meanings of the measurements taken for that device. A measurement can contain up to 5 values, and the meanings of those five values are defined by five attributes in the class table. These attributes describe what the numbers in the measurement mean. Devices belonging to a certain object class may have no measurements, or may need less than 5 values for a measurement. Therefore, the OC_MEASURETYPEx attributes are optional.

Icon attributes

The OC_ICONX attributes, where X is 0, 20, 40, 60 or 80, represent icons that are meant to be used for displaying object of this class depending on their current fill level. The current level of the object would be approximated to 0, 20, 40, 60 or 80 per cent, and the corresponding icon would be used. These attributes are not actually used by the web client made by HZB, but have been left it as an option if other facilities want to use it. These icons are meant to be used for object classes that hold Helium, or for gas counters.

Display Priority

The web client made at the HZB displays floor plans of a facility, with various fixed positions in it. Multiple objects can be located in the same position, and the fixed position itself is also an object. Therefore, the OC_DISPLAYPRIORITY attribute is used to prioritise objects of a certain class so that they are more likely to be displayed on the floor plan. The lower the value of OC_DISPLAYPRIORITY, the higher the display priority, thus the object with the lowest value will be displayed. Positions themselves never overlay anything.

Object class table

Attribute name	Attribute meaning	Data type	Mandatory	Notes
OC_ID	ID of class	24-bit Integer	Yes	It is the primary key.
OC_FUNCTION_ID	ID of the function of this class	24-bit Integer	Yes	It is a foreign key to the primary key of the GAM_FUNCTION table.
OC_NAME	Name of this class	String, up to 50 bytes in size	Yes
OC_POSITIONTYPE	Defines how objects are displayed on floor plans	Integer, with 2 digits at most	Yes	Meaning of each integer not yet decided, more information to come later.
OC_COMMENT	Comments related to this class	String, up to 1000 bytes in size	No
OC_MEASURETYPE1	What the first value of a measurement represents, and its units of measurement	String, up to 100 bytes in size	No
OC_MEASURETYPE2	What the second value of a measurement represents, and its units of measurement	String, up to 100 bytes in size	No
OC_MEASURETYPE3	What the third value of a measurement represents, and its units of measurement	String, up to 100 bytes in size	No
OC_MEASURETYPE4	What the fourth value of a measurement represents, and its units of measurement	String, up to 100 bytes in size	No
OC_MEASURETYPE5	What the fifth value of a measurement represents, and its units of measurement	String, up to 100 bytes in size	No
OC_ICON0	File path to the icon for representing the device when it is at 0% capacity.	String, up to 500 bytes in size	No
OC_ICON20	File path to the icon for representing the device when it is at 20% capacity.	String, up to 500 bytes in size	No
OC_ICON40	File path to the icon for representing the device when it is at 40% capacity.	String, up to 500 bytes in size	No
OC_ICON60	File path to the icon for representing the device when it is at 60% capacity.	String, up to 500 bytes in size	No
OC_ICON80	File path to the icon for representing the device when it is at 80% capacity.	String, up to 500 bytes in size	No
OC_ICON_ALARM	File path to the icon for representing the device in an alarm state	String, up to 500 bytes in size	No
OC_DISPLAYPRIORITY	Determines if objects of this class are prioritised when multiple objects are in the same position on a floor plan in the web client	Integer from 0 to 9	No	Value is 1 for high priority, 2 for medium priority, 3 for low priority, and 0 for when the object is not prioritised.
OC_DF_ID_1	ID of the first display format of this class.	24-bit Integer	No	It is a foreign key to the GAM_DISPLAYFORMAT table.
OC_DF_ID_2	ID of the second display format of this class.	24-bit Integer	No	It is a foreign key to the GAM_DISPLAYFORMAT table.
OC_DF_ID_3	ID of the third display format of this class.	24-bit Integer	No	It is a foreign key to the GAM_DISPLAYFORMAT table.
OC_DF_ID_4	ID of the fourth display format of this class.	24-bit Integer	No	It is a foreign key to the GAM_DISPLAYFORMAT table.
OC_DF_ID_5	ID of the fifth display format of this class.	24-bit Integer	No	It is a foreign key to the GAM_DISPLAYFORMAT table.