org.universAAL.lddi.abstraction

Interface ExternalDatapoint

public interface ExternalDatapoint

An ExternalDatapoint is a readable and / or writable datapoint outside the universAAL network. It is assumed that ontological properties of instances of ExternalComponent can be mapped to such datapoints. Communication gateways may pack all the info (no matter if a simple address or a complex structure) needed for mapping ontological properties of reachable external components in objects that implement this interface and store / fetch it for their list of components using ExternalComponent.addPropMapping(String, ExternalDatapoint) / ExternalComponent.getDatapoint(String).

It is important that gateways map each ontological property of a distinct external component to a single instance of this class. Therefore, in cases that different addresses have to be used for reading and writing, gateways will have to encapsulate this complexity properly within objects that implement this interface. A way to do so, is to define the specific classes for implementing this interface the following way:

Another important point is related to the info needed for realizing the read and write actions; in the above text, this was most of the times reduced only to the addressing aspect, but often also type info as well as hints for converting the external values to values compatible with the used ontological model have to be included. On the other hand, even the "addressing" aspect may not be resolved by just of an integer value. As a simple example, a modbus gateway needs in addition to an address also the size of each read or write access in bits / bytes / words.

Method Summary

Modifier and Type	Method and Description
ExternalComponent	getComponent() Returns the external component to which this datapoint belongs.
String	getProperty() Returns the URI of the ontological property that maps to this datapoint.
boolean	isReadOnly() If this method returns true, it means that the status / value reachable at this address can be read but cannot be changed.
boolean	isWriteOnly() If this method returns true, it means that the status / value reachable at this address can be changed but cannot be read.

Method Detail

isReadOnly

boolean isReadOnly()

If this method returns true, it means that the status / value reachable at this address can be read but cannot be changed. In that case, isWriteOnly() must return false. If this method returns false, the interpretation will depend on the return value of isWriteOnly(): in case of true, the status / value reachable at this address cannot be read but can be changed. Otherwise, it is both read- and writable. No implementation of ExternalDatapoint may return for both this and the isWriteOnly() method simultaneously true!

isWriteOnly

boolean isWriteOnly()

If this method returns true, it means that the status / value reachable at this address can be changed but cannot be read. In that case, isReadOnly() must return false. If this method returns false, the interpretation will depend on the return value of isReadOnly(): in case of true, the status / value reachable at this address cannot be changed but can be read. Otherwise, it is both read- and writable. No implementation of ExternalDatapoint may return for both this and the isReadOnly() method simultaneously true!

getComponent

ExternalComponent getComponent()

Returns the external component to which this datapoint belongs.

getProperty

String getProperty()

Returns the URI of the ontological property that maps to this datapoint.