I have a last question  Is it possible to import my collection row by row for like every 5 seconds? I want to create a streaming and always want to refresh my database. I think it's also okay if i can import my whole collection for like every hour. Thank you again in adance.

Thank you very much Steve! Everything works fine now.  

Im trying to store the properties "name", "playcount", "listeners", "mbid", "url" not the "artist" or the "artists" property. I think that my document class definition is at the bottom of my code :

Class User.API

{

ClassMethod getFile() as %Status

{

       IF $SYSTEM.DocDB.Exists("db.Streamingdatabase") {

             SET db = ##class(%DocDB.Database).%GetDatabase("db.Streamingdatabase")

             }

             ELSE {

                    SET db = ##class(%DocDB.Database).%CreateDatabase("db.Streamingdatabase")

                    }

             DO db.%CreateProperty("Name","%String(MAXLEN=200)","$.name")

             DO db.%CreateProperty("Duration","%Integer","$.duration")

             DO db.%CreateProperty("Playcount","%Integer","$.playcount")

             DO db.%CreateProperty("Mbid","%String(MAXLEN=200)","$.mbid")

             DO db.%CreateProperty("Url","%String(MAXLEN=200)","$.url")

             DO db.%CreateProperty("StreamableText","%Integer","$.streamable/#text")

             DO db.%CreateProperty("StreamableFulltrack","%Integer","$.streamable/fulltrack")

             DO db.%CreateProperty("ArtistName","%String(MAXLEN=200)","$.artist/name")

             DO db.%CreateProperty("ArtistMbid","%String(MAXLEN=200)","$.artist/mbid")

             DO db.%CreateProperty("ArtistURL","%String(MAXLEN=200)","$.artist/url")

             DO db.%CreateProperty("Rank","%Integer","$.@attr/rank")

             SET httprequest=##class(%Net.HttpRequest).%New()

             DO httprequest.Get("http://ws.audioscrobbler.com/2.0/?method=user.gettoptracks&user=ducanhtr...")

             DO db.%FromJSON(httprequest.HttpResponse.Data)

}

}