In a streamMap, the nullField element acts as a placeholder that always delivers a NULL value to the stream. This lets you add extra fields to a source stream to get the configuration you want.
adapter (required, limit one)
|----publication (required, limit one)
|----streamMaps (required, limit one)
| '----streamMap (required)
| |----itemName (required, limit one)
| |----serviceName (optional)
| |----sequenceNumber (optional)
| |----itemStale (optional)
| |----dataField (required)
| |----updateNumber (required)
| |----dateTimeField (optional)
| |----FIDListField (optional)
| '----nullField (optional)
|----recordTypeMap (optional)
| '----recordType (optional)
|----rfa (required, limit one)
'----itemLists (required, limit one)
'----itemList (required)
'----item (optional)
streamMap
None
| Name | Description | Requirement |
|---|---|---|
| name | A string that appears in any adapter-related log entries | Optional |
When experimenting with a project, you can use a nullField to temporarily stop feeding data into one column of the stream. In this case, you can simply keep the name of the dataField that you are temporarily replacing, as in the following example.
<streamMap name="stream1">
<itemName key="true"/>
<FIDListField />
<!-- serviceName / -->
<sequenceNumber />
<itemStale/>
<dataField name="BID"/>
<dataField name="ASK"/>
<nullField name="TRDPRC_1"/>
<dataField name="ACVOL_1"/>
<dateTimeField timeName="TIMACT" dateName="ACTIV_DATE"/>
</streamMap>
The seventh column of the source stream is identified as a placeholder receives a null value in each update from the adapter. It includes the name of the dataField that it replaces for debugging purposes.