Live Data API
Access to live data is via the consolidator - a service that is specifically designed to provide the latest information to clients.
The consolidator is accessed with HTTP (REST) calls.
You can access live information either though a snapshot, which is a single, instant image of the current values, or through a subscription, which notifies you of changes in the data you're monitoring.
SDKs
ARDI ships with two SDK toolkits to allow you to connect to live data with minimal fuss.
If you aren't using one of these languages or you'd like to understand what is going on under the hood, see the documentation below…
Getting the Consolidator URL
The first step (which is handled for you in the SDKs above) is to discover the correct URL for your consolidator.
If you have a multi-site ARDI system, each site has its own unique consolidator, running on a different TCP port.
If you send a HTTP GET request to
http://<site url>/api/connect
This will return an XML file that will indicate the correct host address and port number to use to access the consolidator.
API Functions
| Name | Usage |
|---|---|
| snapshot | Used to get all of the current values for a set of data points. This function does not create a subscription. |
| subscribe | Returns all current values and creates a subscription to allow you to track changes using the updatefunction |
| unsubscribe | Closes a subscription created with subscribe |
| update | Returns the data that has changed since the last update/subscribe request |
Example Life-Cycle
This is an example of how an application usually connects to and monitors live data from an ARDI server…
Find the Consolidator Host & Port from <ardi-server>/api/connect
Create A New Subscription from <consolidator>/subscribe?codes=<points>
While Running...
Keep Updating The Data from <consolidator>/update?id=<subscription-id>
Unsubscribe from <consolidator>/unsubscribe?id=<subscription-id>
Remember to pass '&format=json' to each of these functions if you'd prefer your results in JSON format rather than XML.