In a streamMap, the nullField element acts as a placeholder that always delivers a NULL value to the Event Stream Processor source 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)
| |----dataField (required)
| |----hiResTimestampField (optional)
| |----imageField (required for L2 data)
| |----itemName (required, limit one)
| |----itemStale (optional)
| |----marketByOrderKeyField (required)
| |----marketByPriceKeyField (required)
| |----marketMakerKeyField (required)
| |----nullField (optional)
| |----respTypeNumField (optional)
| |----sequenceNumber (optional)
| |----serviceName (optional)
| '----updateNumber (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 |
| dateName | A string that appears in any adapter-related log entries | optional |
| timeName | A string that appears in any adapter-related log entries | optional |
When experimenting with a project, you can replace a dataField or dateTimeField element with a nullField to temporarily stop feeding data into any column of the stream.
You need not modify any attribute(s) of the dataField or dateTimeField you are temporarily replacing, as the following example shows.
<streamMap name="marketByOrderStream">
<itemName key="true"/>
<!-- 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 sixth column of the source stream is identified as a placeholder that receives a null value in each update from the adapter. It includes the name of the dataField that it replaces for debugging purposes.