Durable Generic Streaming Sample
The Durable Generic Streaming Visualforce sample shows you how to use replay
options to subscribe and receive durable generic event notifications.
Create a Streaming Channel
You must have the appropriate Streaming API permissions enabled in your org.
Create a StreamingChannel object by using the Salesforce UI.
- Log in to your Developer Edition org.
- If you’re using Salesforce Classic, under All Tabs (+), select Streaming Channels. If you’re using Lightning Experience, from the App Launcher, select All Items, and then click Streaming Channels.
- On the Streaming Channels page, click New to create a streaming channel.
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Enter /u/TestStreaming in Streaming Channel
Name and add an optional description. Your new Streaming Channel page looks
something like this:
- Click Save. You now have a streaming channel that clients can subscribe to for notifications.
StreamingChannel is a regular, creatable Salesforce object, so you can also create one programmatically using Apex or a data API like the SOAP API or REST API, or using a tool such as the Developer Console. For more information, see Reference: StreamingChannel.
Use a Visualforce Page to Generate and Replay Generic Events
In this step, you use a Visualforce page to generate your own
streaming events and replay those events by using different options.
The Visualforce page
simulates a streaming client that subscribes to events with options to replay events.
The Visualforce page allows you
to supply the event’s message and specify the number of messages to create. The page
listens to events and displays the received events in the Notifications section. After
generating events, you can replay events starting from:
- All events after a particular event specified by a replay ID.
- The first event broadcast right after subscribing (replay option -1).
- The earliest retained event in your org that’s less than 24 hours old (replay option -2). The sample uses replay option -2 as the default option.
This Visualforce sample is part of the Durable Streaming Demo app.
- From App Launcher, open the Durable Streaming Demo app.
-
Click the Durable Generic Streaming Demo tab.
The Visualforce page loads and subscribes to the test channel you created earlier.
- In the Visualforce page, generate some events. Enter any text for the message text, for example, Test message. For Number of Events, enter 10.
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Click Generate.
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To change the point in time when events are read, enter the replay ID to read
from in the Replay From Id field. For example, to read
all events after the event with replay ID 5, enter 5.
Then click Update Subscription.
The Notifications section is updated and shows only the last five events starting from replay ID 6.
-
To receive only the events that are sent after you subscribe, enter
-1 in the Replay From Id
field. Then click Update Subscription.
The Notifications section is cleared, because only new events from this point on are shown.
-
Generate some new events like you did in step 3 with New
events for the message.
The Notifications section is updated with the new events and doesn’t show the old events.
-
Switch the replay option back to -2.
The page displays all events, including events that were sent earlier.