Hi
I am using PI Web API in my React application to load data from PI AF. My requirement is to load snapshot values of multiple attributes of a single element. Currently I am fetching multiple attribute values for multiple elements. Certainly this is not the ideal case. To minimize the pi web api calls, I am looking for something that atleast I could load all attribute values of a single element in one go.
Is it possible with pi web api?
Thanks.
Vivek
The way to go is to use the StreamSet controller which is a bulk call. You can specify some filters to determine which attributes you want.
Hello Vivek,
Since you want to get the attributes from a single element, Eugene's solution is probably the best choice. Nevertheless, there are other options that you should be aware of:
1)If you want to load only a subset of the attributes of a single element, GetValuesAdHoc GET streamsets/value might be a more interesting solution. In this case, you define the Attribute's Web IDs instead of the Element Web ID. Since PI Web API would have to load less attributes, there might be a performance improvement.
2)If you have too many attributes to load, you might load in smaller chunks. This means that you would call GetValuesAdHoc GET streamsets/value many times but you would receive faster responses. Probably you will be able to show the data to the user as soon as each HTTP request is completed, improving the user experience.
3)If you need to get the Web ID, you might consider using PI Web API Batch since you can get the Web ID + data with a single HTTP request. Note that is not recommended to use PI Web API Batch for any type of requests since it requires more memory from the PI Web API server. A better approach actually would be to use Web ID 2.0 in order to generate the Web ID on the client. In this case, you don't need to make an HTTP request just to get the Web ID. If you know the path, you can generate it using JavaScript.
4)Since you want to get the snapshots, you might be interested in signing up for updates instead of the retrieve snapshots frequently (if this is the case). Signing up for updates means you would receive just the most recent data updates. You don't have to receive all snapshots values if they are repeated or old. Please consider using: Channels (Core Services) or Stream Updates (Core Services)
Finally, the key for web performance is: try to load the minimum amount of data needed (with hopefully the minimum amount of HTTP requests).
Hope this helps!
Hi Marcos
Thanks for the reply. I want to load multiple elements and each element has multiple attributes. I am trying to create a table with elements in first column and attributes in rest of the columns. Just to see the latest real time value.
Hi Vivek
You can use PI Web API Batch to post queries in bulk than individual request.
Reference : Webinar: PI Web API - Batch