Platform Events in Salesforce

Introduction

In this blog post, I am going to explain about platform events a new feature generally available from Summer ’17 release as part of the “Enterprise Message Platform” which provide event driven architecture.

Let’s talk about Event Driven Architecture 

Salesforce event-driven architecture is consists of event producers, event consumers, and channels.  Platform events simplify the process of communicating changes and responding to events. Publishers and subscribers communicate with each other through events. One or more subscribers can listen to the same event and carry out actions .with an Event-driven architecture each service publishes an event whenever it updates or creates a data. Other services can subscribe to events.It enables an application to maintain data consistency across multiple services without using distributed transactions.  Let us take an example of order management. When the Order management app creates an Order in a pending state and publishes an OrderCreated event.The Customer Service receives the event and attempts to process an Order. It then publishes an OrderUpdate event.Then OrderUpdate Service receives the event from the changes the state of the order to either approved or canceled or fulfilled.The following  diagram show the event driven architect

Capture

Terminology 

Event
A change in state that is meaningful in a business process. For example, a placement o of an order is a meaningful event because the order fulfillment center requires notification to process the order.
Event Notifier 
A message that contains data about the event. Also known as an event notification.
Event producer
The publisher of an event message over a channel.
Channel
A conduit in which an event producer transmits a message. Event consumers subscribe to the channel to receive messages.
Event consumer
A subscriber to a channel that receives messages from the channel. A change in state that is meaningful in a business process.

Looks like Streaming API, But Really not 

But when you overlook at Platform events it makes similar to Streaming API and most of the futures including the replayID and durability but below makes the difference between with streaming API.

  • Platform  events are special kinds of entity similar to custom object custom object
  • You can publish and consume platform events by using Apex or a REST API or SOAP API. Platform events integrate with the Salesforce platform through Apex triggers. Triggers are the event consumers on the Salesforce platform that listen to event messages.Unlike custom objects, you can’t update or delete event records. You also can’t view event records in the Salesforce user interface, and platform events don’t have page layouts. When you delete a platform event definition, it’s permanently deleted.
  • Platform events may be published using declarative tools (Process Builder)
  • platform events can also be subscribed to using APEX  or decoratively process builder  and flows

Another major,off-course really impressive one is you can publish changes from apex trigger and you can consume from apex trigger trigger

Publishing and subscribing Platform events 

Publishing and subscribing the platform event are more flexible. You can publish event messages from a Force.com app or an external app using Apex or Salesforce APIs and you can subscribe from the Salesforce or external apps or use long polling with cometD as well.

Let’s take an Example:- 

Now I am going to explain step by step to set up, publish and consume events. What we are going to do it Employee Onboarding Process. Now Once an external app publishes the events, we are going to create an account and when Salesforce publish onboarding events another system is going to receive the platform events.

1: – Define a Platform event


You can define platform event similar like custom object, go to setup –> develope –> Platform events –> create new platform events as shown below.

Capture

By seeing it looks like custom objects but here are the few major considerations.

  • Platform event is appended the __e suffix for API name of the event.
  • you can’t query Platform events through SOQL or SOSL.
  •  you can’t use Platform in reports, list views, and search.
  •  published platform events can’t be rolled back.
  • e methods aren’t supported with platform events.
  • All platform event fields are read-only by default
  • Platform events don’t have an associated tab
  • Only after insert Triggers Are Supported
  • You can access platform events both through API and declaratively
  • You can control platform events though Profiles and permissions

2: – Publishing Platform Events

You can publish events using an Apex method or with declarative tools, such as Process Builder or the Cloud Flow Designer or you can publish events using Salesforce API. we are going to seeing all the ways how to publish the platform events.

Publish Using Apex

you can publish platform events by using apex trigger or execute anonymously and batch Apex etc.But here I am going to publish by using Apex triggers. A trigger processes platform event notifications sequentially in the order they’re received and trigger runs in its own process asynchronously and isn’t part of the transaction that published the event.

 

 Now if you can see, Salesforce has a special class to publish the platform events EventBus which is having methods publish method. once the event is published you can consume the events from the channel

Publish Using Process Builder 

You can publish platform events using the declarative tools like process builders and flows. Here is the image shows the platform events insert by using process builder.

Capture

Publish Events by Using API

Now I am going to see another way of publishing events from API. I am going to use the workbench to publish the events.
Capture

3: – Subscribe for Platform events from the channel

You can now subscribe the platform events from the Platform events object trigger which is created in step 1. Here is the sample trigger show how you can handle the subscribed events.Here simply I am creating the new accounts from the platform even but you can implement your own business logic to update the data .

 

Here is the simple visual force page that consumes the platform events which you published. This page is built on cometD.
you can consume the platform events by using this  URI /event/Employee_On_boarding__e and the Complete code is here below.

Key points


1 . Platform events are executed under ” Automated Process entity.” So you have set Automated Process in debug logs
2. You can control the Platform events on Profile and permission sets
3.You can see all the platform events that are subscribed under Platform events objects.
Capture
4. Platform events have lifecycles state like Running, Ideal, Suspended,, Error, Expired
5.Platform events are having retry mechanism.