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Back in September, I explained how to use the Salesforce Analytics API on a Visualforce Page; this time, I’ll show you how to use the Force.com Streaming API to add life to your data.

Let’s say you’ve written a marvelous UI that leverages the Analytics API (or the REST API, or JavaScript Remoting) to present data in a brilliantly digestible format:

Analytics Chart on a Visualforce Page

Now, this is a snapshot of your analysis – how do you know it’s still current? Enter the Streaming API – our page can subscribe for notifications on changes to the underlying data and prompt the user to rerun the report. Take a look at the page in action:

//www.youtube.com/watch?v=PHM4eycBDK0

Grab the source for the entire page here; I’ll walk through the changes to the static Analytics page from last time.

The Streaming API implements a publish/subscribe model. You (the developer) create a topic based on a SOQL query, and your client app can subscribe for notifications when the results of that query change. So, the first thing I did was to follow the instructions, in the Streaming API Developer’s Guide, on creating a PushTopic record for notifications on any change to Merchandise Name or Quantity fields – the raw data that feeds into my analysis.

This is the code I ran, in the ‘Execute Anonymous’ window of the Developer Console:

I followed the instructions to test my PushTopic in Workbench. Updating a Merchandise record’s quantity correctly generates a notification:

The first thing my page needs to do is to include the CometD JavaScript libraries:

The following code, in the jQuery $(document).ready() handler, initializes the CometD library and subscribes for notifications on the MerchandiseUpdates topic:
The #rerun button click handler hides the button and runs the report again:

Why do I show a button rather than simply running the report automatically? Well, running a report is relatively expensive, computationally speaking; it’s wasteful to run the report on every data change, regardless of whether the user is watching or not. So, to be good multi-tenant citizens, we prompt the user to rerun the report.

Are you using the Analytics API yet? Let us know in the comments…

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