Loading a Virtual Source
A virtual source is a source that is not static. You might, for example, use a virtual source for a file that is being frequently modified. The srcId of a virtual source is a negative integer. The external Id of a virtual source begins with the ListerReference (the Lister class alias), commonly :TEMP.
Adding a virtual source does not update NLP statistics. For this reason, using a virtual source may be desirable when you wish to temporarily add sources for a specific purpose without incurring the overhead of revising the domain statistics. You should use a virtual source when adding a source that is being continuously modified, such a source in the process of being written. Because the virtual source Id is a negative number, it is easy to distinguish virtual sources from regular sources. Different methods are used to delete virtual sources and regular sources.
You can load virtual sources using loader.SetLister()Opens in a new tab and loader.ProcessVirtualList()Opens in a new tab or loader.BufferSource()Opens in a new tab and loader.ProcessVirtualBuffer()Opens in a new tab. The following program loads a virtual source using ProcessVirtualBuffer().
DomainCreateOrOpen
SET dname="mydomain"
IF (##class(%iKnow.Domain).NameIndexExists(dname))
{ WRITE "The ",dname," domain already exists",!
SET domoref=##class(%iKnow.Domain).NameIndexOpen(dname)
GOTO DeleteOldData }
ELSE
{ WRITE "The ",dname," domain does not exist",!
SET domoref=##class(%iKnow.Domain).%New(dname)
DO domoref.%Save()
SET domId=domoref.Id
WRITE "Created the ",dname," domain with domain ID ",domId,!
GOTO SetEnvironment }
DeleteOldData /* This DOES NOT delete virtual sources */
SET stat=domoref.DropData()
IF stat { WRITE "Deleted the data from the ",dname," domain",!!
SET domId=domoref.Id
GOTO SetEnvironment }
ELSE { WRITE "DropData error ",$System.Status.DisplayError(stat)
QUIT}
SetEnvironment
SET config="VSConfig"
IF ##class(%iKnow.Configuration).Exists(config) {
SET cfg=##class(%iKnow.Configuration).Open(config) }
ELSE { SET cfg=##class(%iKnow.Configuration).%New(config,1)
DO cfg.%Save() }
CreateLoader
SET myloader=##class(%iKnow.Source.Loader).%New(domId)
VirtualSource
SET node="",(total,status)=0
FOR { SET node=$ORDER(^VendorData(node),1,data) QUIT:node=""
SET company=$LIST(data,1) QUIT:company=""
SET address=$LTS($LIST(data,2))
SET total=total+1
SET status=myloader.BufferSource("SourceTest"_total,company)
SET status=myloader.BufferSource("SourceTest"_total,address)
}
SET status=myloader.ProcessVirtualBuffer(config)
SET vsrclist=myloader.GetSourceIds()
FOR i=1:1:$LL(vsrclist) {
SET srcid=-$LIST(vsrclist,i)
WRITE "External Id=",##class(%iKnow.Queries.SourceAPI).GetExternalId(domId,srcid)
WRITE " Source Id=",srcid,!
WRITE " Sentence Count=",##class(%iKnow.Queries.SentenceAPI).GetCountBySource(domId,$lb(srcid)),!
}
Note that the %iKnow.Queries.SourceAPI.GetCountByDomain() method does not count virtual sources. You can determine if a virtual source has been loaded by invoking %iKnow.Queries.SourceAPI.GetExternalId(domId,-1). Here -1 is the srcId of the first virtual source loaded.
By default, many NLP queries process only ordinary sources and ignore virtual sources. To use these queries to process a virtual souce you must specify a vSrcId parameter value for the query method.
