References

References are used to indicate the location of data. Depending on the context, the reference may be used to read data (i.e, data will be fetched from wherever the reference points to) or to write data (data will be saved to wherever the reference points to).

References may refer to any value that represents Iotellect internal data. The generic syntax of a reference is:

schema/server^context:entity(parameter_list)$field[row]#property

All parts of a reference are optional, so the shortest possible reference is the empty string.

Using References in Expressions

References must be enclosed into curly brackets when inserted into expressions.

They're resolved when the expression is evaluated. It looks like this: {temperature} <= 100. In this case, temperature is a reference.

Reference Schema

The reference schema defines how the system resolves the rest of the reference. Schemas are widely used in computing. For example, in the address http://www.domain.com, the http:// part is the schema. It tells your browser that this is an HTTP link. An FTP link can have a different structure, such as ftp://user:xxx@domain.com. Here again, the ftp:// part defines the schema, which indicates how the program should handle the rest of the link.

In Iotellect, schemas are used to refer to various parts of the system. For example:

env/ schema is used to refer to environment variables (which are properties immediately concerning the current operation being executed),

form/ schema is used in UI Builder to refer to the properties of graphical components in that particular dashboard.

In order to resolve a variable as a Standard Reference, the schema is omitted. When the schema is omitted, it indicates that the references points to data coming from a context variable, a function, or a cell of a Data Table, or any other element of the of Data Model.

For example, a reference like form/TextField1:text uses the form/ schema, and refers to the "text" property of a dashboard component called "TextField1". A reference like users.admin:childInfo$firstname includes no schema, and refers to the first name of user "admin", which is a field of the childInfo variable.

Reference Schemas Used in Iotellect

Schema

Description

Not specified

Indicates that reference is a standard reference.

action/

Used to launch an action, e.g. from a widget or dashboard binding target.

env/

Points to an environment reference.

form/

UI component reference. Such references are used in widget and dashboard binding expressions.

menu/

Used inside a widget or dashboard binding activator to react to a context menu item selection.

previous/

Used in chart dataset expressions (see Event-based Data and Variable-based Data properties of the Chart component). These use the same format as used for the Standard Reference. However, Default Data Table pointed by such reference is a Data Table containing the value for the previous data point (i.e. event data or value of changed variable).

statistics/

Used to refer statistical data from chart dataset.

table/

When used as a data table binding target, instructs the system to replace the whole table those binding is being processed by the one returned by current binding's expression.

web/

Used in web dashboard binding expressions to initiate a special action, such as redirect to another web page.

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