Keywords¶

Words described next with an _ before them are system keywords with specific meaning for VDMS. Their usages are listed in the command examples as appropriate.

• _ref: Local id for reference (can be defined in one call and reused in following calls). _ref is valid within a single transaction and must be a number in the range [1,10000].

• _date: VDMS can parse certain date formats but the way to specify that in JSON is through a string but prefix it with this keyword. The supported format for the date is: Mon Aug 7 12:59:24 PDT 2017. One Example of a query using this keyword:
  

  "AddEntity" : {
      "class" : "Visit",
      "_ref": 4567,
      "properties" : {
          "start": {"_date": "Mon Aug 7 10:59:24 PDT 2017"},
          "end":   {"_date": "Mon Aug 7 12:59:24 PDT 2017"}
      }
  }
  

• _blob: Similar to _date, we want to distinguish between regular strings and blobs. This is to specify a property that goes in the metadata database. In case of images etc, we will talk about blobs but those would be provided as or returned along with the string json.

• _globalid: All entities including images have a global system id associated with them.