Using the Streaming API allows you to receive events for changes to Salesforce data that match a SOQL query you define, in a secure and scalable way.

This events will be converted to Mule events and dispatched to your flows.

Publishing a topic

Before you can start receiving events for changes in Salesforce, you must first create a PushTopic. A PushTopic is a special object in Salesforce that binds a name (the topic's name) and SOQL together. Once a PushTopic is created you can then subscribe to it by using only its name.

There are several ways in which you can create a PushTopic, we will cover using Salesforce itself and using this connector. You could potentially also use Workbench.

Using Salesforce

First, select Your Name | System Log.

Then, on the Logs tab, click Execute.

Finally, in the Enter Apex Code window, paste in the following Apex code, and click Execute.

PushTopic pushTopic = new PushTopic();
pushTopic.Name = 'AccountUpdates';
pushtopic.Query = 'SELECT Id FROM Account';
pushTopic.ApiVersion = 23.0;
insert pushTopic;

Using our connector

You can either use the create operation but also you can use our exclusive publish-topic operation as follows:

<sfdc:publish-topic name="AccountUpdates" query="SELECT Id FROM Account"/>

Subscribing to a topic

Once your topic has been created, you can start receiving events by subscribing to it. Our subscribe-topic acts like an inbound endpoint and it can be used as such.

<flow name="accountUpdatesSubscription">
    <!-- INBOUND ENDPOINT -->
    <sfdc:subscribe-topic topic="AccountUpdates"/>
    <!-- REST OF YOUR FLOW -->
    <logger level="INFO" message="Received an event for Salesforce Object ID #[map-payload:Id]"/>
</flow>

A Mule flow is divided in two. The first portion of it is usually an inbound endpoint or a message source. It is an entity that will receive/generate events that will later be processed by the rest of the flow. The other portion is a collection of message processors which will processes the messages (aka events) received/generated by the inbound endpoint.

Every time our subscription to AccountUpdates receives an event it will execute the rest of the flow. In the case of this example it will print a message to the log at INFO level.

Examining the Events

The event that gets pushed down the flows contains information about the Salesforce data that has changed, how it changes, and when. Usually the raw JSON that the subscription receives looks something like this:

{
  "channel": "/topic/AccountUpdates",
  "data": {
    "event": {
      "type": "created",
      "createdDate": "2011-11-35T19:14:31.000+0000"
    },
    "sobject": {
      "Id": "a05D0000002jKF1IAM"
    }
  }
}

Our connector will parse this information and send you something that a flow can actually work with.

Inbound Properties

Some information will get passed along as inbound properties:

Property Name	Scope	Maps to
channel	INBOUND	channel JSON property
type	INBOUND	type JSON property in data
createdDate	INBOUND	createdDate JSON property in data

Actually besides channel, every property inside _event_ will be available as an INBOUND property.

Payload

The payload of the event is actually a Map. That map contains everything inside the sobject object in the received JSON data. It offered as a map for the convenience of being able to use map-payload expression evaluator to extract the information of the SObject.

See how in the Subscribing to a topic example we used #[map-payload:Id] to print the Id of the SObject.