InfoBus data items

What is a data item?

A data item is a Java object that provides the InfoBus access to a packet of data. This access is structured for exchange of the data among members of the InfoBus using standardized method calls. A data item also has standard methods for describing the data and listening for changes in the data. By using InfoBus data items, Java components can call the same methods on every provider or consumer of data in order to transfer data, without dealing with data's internal representation.

An InfoBus object manages both the components that publish or listen for data and the requests for data access. InfoBus members identify a data item by its data item name. When one applet makes data available via the InfoBus, other applets can then process or display the data.

A data item object typically doesn't actually contain the data, particularly for large-size data. It provides methods for accessing data that can be stored elsewhere, for example with the component that produces it.

How do you create different kinds of data items?

The InfoBus provides a number of Java interfaces for accessing different types of data via a data item object. Data items implementing the following interfaces are available via script:

ImmediateAccess

The ImmediateAccess type is for data consisting of a single value or object. Using the eSuite scripthelper applet, you can publish a single string as a data item of type ImmediateAccess.

ArrayAccess

The ArrayAccess type is for data consisting of a multi-dimensional array of values. You can create an ArrayAccess data item in the following ways using script:

Example

Charting file data example

See also

InfoBus overview
ScriptHelper applet
InfoBusVector class
FileReader applet
Data set files