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M&M FDT 1.2.1 Online Specification |
Interfaces and Methods - Schemas - FDT Specification - Quicklinks - Abbreviations
4.3.18.3 IDtmSingleDeviceDataAccess::ReadRequest()
| This method can be called in the states: |    |
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HRESULT ReadRequest ( [in] FdtUUIDString invokeId, [in] FdtXmlDocument itemSelectionList ); |
Description:
| ReadRequest performs asynchronous exchange of a data structure with the related device via the DTM. |
Parameters:
| invokeId | Unique identifier for the request |
| itemSelectionList | List of required items described by a DtmItemSelectionList specified by the DTMItemListSchema |
Return Value:
Behavior:
| Via this method a Frame Application may request data from a device. Error information will be handed over to the Frame Application via the related response XML-Document. If a request can not be accepted by the DTM it is possible to send the response within the call. Execution of the ReadRequest() method must not change the data of the instance data set. The DTM must always accept the request. If the request cannot be processed, the reason for failure must be provided asynchronously as part of the response. The response (either failure or the result) must be provided at IDtmSingleDeviceDataAccessEvents::OnReadResponse(). |
Comments:
| In order to inform the Frame Application regarding ongoing activities it is recommended to fire the IDtmEvents::OnProgress() event while a response is pending. The DTM should be able to handle more than one request at a time. The order of execution is like the order of the requests. For each request there should be a corresponding response. If a request can not be executed, an appropriate response must be provided. |
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