MongoDB DSLink

A DSLink for MongoDB.

Usage

Ensure you have MongoDB installed somewhere. This can be on the server on which the link runs, or on a remote machine. See this page for how to install MongoDB.

Invoke Add Database and input a name and the URL. This would be something like mongodb://127.0.0.1/dsa if the you installed the server locally.

From there, you can create watch groups which allow you to setup a group of paths to subscribe.

Data is stored in the database with collection names in the format of {group}:{path}. For a logged point in the group example with a path of /downstream/Example/message, the collection that stores the history would be example:/downstream/Example/message.

Collection Schema

All logged data has _id, timestamp and value fields. When filtering for content ensure to prepend value to your data queries.

Example:

{
  "_id": "5690582905c18833e62e1108",
  "timestamp": "2016-01-09T00:45:29.010Z",
  "value": 1153.28515625
}

JavaScript Examples

The Evaluate JavaScript action allows you to perform JavaScript evaluation server-side. This is the same thing that the mongo command line client utilizes.

Fetch all data in a collection

The following will fetch all the data in the example:/downstream/Example/message collection.

var cursor = db.getCollection("example:/downstream/Example/message").find();

return cursor.toArray();

Fetch data that has a value less than 50

The following will fetch all the data in the system:/downstream/System/CPU_Usage collection where the value is less than 50.

var cursor = db.getCollection("system:/downstream/System/CPU_Usage").find({
  "value": {
    "$lte": 50
  }
});
return cursor.toArray();

Filter json documents originating from logging DSA map objects

The following will fetch all the tweets in the twitter:/downstream/twitter/testTweet/test collection that have images.

More twitter query examples: http://stats.seandolinar.com/collecting-twitter-data-storing-tweets-in-mongodb/

//Note the prepended 'value'
var cursor = db.getCollection("twitter:/downstream/twitter/testTweet/test")
.find({"value.extended_entities" : { "$exists" : "true"}})
.limit(5);
return cursor.toArray();