Update sources (Readers) to work with widgets

[dborovcanin]

Related to https://github.com/absmach/magistrala/issues/1966.

[ianmuchyri]

Some of the items we need to focus on include:

• [ ] Determining the dataset length to avoid fetching large data for charts
• [ ] Data aggregation?
• [ ] Data fetch interval (e.g if data is fetched for 1 day, should the interval between each data be 1hr, 1minute, 2hrs e.t.c). This will also be related to the data aggregation
• [ ] Polling of database
• [ ] Web socket connection for widgets that display realtime data e.g guages.

[felixgateru]

Type of chart

• Analogue gauge
• Pressure gauge
• Temperature

  Type of data required

  Realtime data

Potential modifications

1. Query data by thing Id and name of sensor paramter
2. Upgrade protocol to ws for real time data streaming or
3. Use async time intervals on the frontend.

Type of chart

• Time series line chart
• Range chart
• Area line chart
• Dynamic chart

Type of data required

Y axis data: sensor value X axis data: time data

Potential modifications

1. Query data by thing ID, name of sensor parameter, start period, end period

Type of chart

• Pi chart
• Donut chart

  Type of data required

  Aggregated data from different publishers on a channel for a single named parameter

Potential modification

Query data by thing ID, name of sensor parameter, start period, end period and aggregate

Notes

The return type is maintained as is from sdk.ReadMessages

[dborovcanin]

Currently, we will focus only on data filtering (and aggregation if necessary) to enable charts to work; https://github.com/absmach/magistrala/issues/1966 is a lower priority and will be added in the next release.