====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. 

  *  [[Javascript Live Data API]]
  *  [[Python Live Data API]]

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|snapshot]]|Used to get all of the current values for a set of data points. This function does **not** create a subscription.|
|[[subscribe|subscribe]]|Returns all current values and creates a subscription to allow you to track changes using the //update//function|
|[[unsubscribe|unsubscribe]]|Closes a subscription created with //subscribe//|
|[[update|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...

<code>
   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>
</code>

Remember to pass '&format=json' to each of these functions if you'd prefer your results in JSON format rather than XML.