Value Streams Vs Data Tables

Thingworx Difference between Streams, Value Streams, and Datatables

Hi, everybody

And what would you recommend to use in following case?

I have to store SUM value from the number of Things according to 5 mins intervals.

I've created a simple service which gets the value history from the ValueStream for the desired period and adds the value and Updates the property finally with new SUM value for the desired period. But due to asynchronous ValueStreams if I call 5 times my service fast I'll get only 2 or 3 values added to the SUM value because data is written to disk in 2 seconds (according to default persistent provider) and the next Query will read the previous SUM value.

It should update SUM correctly also the periods in history when one of the RemoteThing  get connected again and uploads historical data.

Would DataTable be more suitable? Or is there other best practice?

Here is the code:

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// params - value = value to be logged, time = DATETIME of property in real time

var period = 300000; //5 min in ms

var periodStart = time.getTime();

periodStart /= period;

periodStart = Math.floor(periodStart) * period;

var periodEnd = periodStart + period - 1;

periodStart = new Date(periodStart);

periodEnd = new Date(periodEnd);

var curTotal = 0;

var params = {

  oldestFirst: undefined /* BOOLEAN */,

  maxItems: 1 /* NUMBER */,

  endDate: periodEnd /* DATETIME */,

  query: undefined /* QUERY */,

  startDate: periodStart /* DATETIME */

};

var res = me.QueryPropertyHistory(params);

if (res && res.rows && res.rows.length > 0){

    curTotal = res.rows[0].totalConsumption;

}

curTotal += value;

//now update value

var itDef = {

   infoTableName : "InfoTable",

   dataShapeName : "NamedVTQ"

};

var itNvtq = Resources["InfoTableFunctions"].CreateInfoTableFromDataShape(itDef);

// NamedVTQ entry object

var newEntry = new Object();

newEntry.name = "SUM"; // STRING

newEntry.time = periodStart; // DATETIME

newEntry.value = curTotal; // VARIANT

newEntry.quality = "GOOD"; // STRING

itNvtq.AddRow(newEntry);

me.UpdatePropertyValues({values: itNvtq /* INFOTABLE */}); //use update property to set current value for thing property correctly

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While tests in design time I'd executed 5 times immediately with value=1 and current time and got as the result only 2 or 3. But expected to see 5.