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Getting Started with Momento Topics in Go

If you need to get going quickly with Go and Momento Topics, this page contains the basic API calls you'll need. Check the Go SDK examples for complete, working code samples.

Install the Momento SDK​

After you have created your Go project, install the Momento Go SDK.

go get github.com/momentohq/client-sdk-go

Get your Momento API key​

You'll need a Momento API key. You can get one from the Momento Web Console. Once you have your token, store it in an environment variable so that the Momento client can consume it:

export MOMENTO_API_KEY=<your api key here>

Note: it is best practice to put the API key into something like AWS Secret Manager or GCP Secret Manager instead of an environment variable for enhanced security, but we are using one here for demo purposes.

Set up a TopicClient​

This code creates the TopicClient that you will use to interact with your pub/sub topic.

credProvider, err := auth.NewEnvMomentoTokenProvider("MOMENTO_API_KEY")
if err != nil {
	panic(err)
}

topicClient, err = momento.NewTopicClient(
	config.TopicsDefault(),
	credProvider,
)
if err != nil {
	panic(err)
}

Publish a message to a topic​

This is an example of publishing a message to a topic called "topic", then catching the return value to check if the publish was successful.

_, err := topicClient.Publish(ctx, &momento.TopicPublishRequest{
	CacheName: cacheName,
	TopicName: "test-topic",
	Value:     momento.String("test-message"),
})
if err != nil {
	panic(err)
}

Subscribe to a topic​

This is an example of subscribing to a topic called "topic". When messages are published to this topic, the code here receives and prints them asynchronously.

// Instantiate subscriber
sub, subErr := topicClient.Subscribe(ctx, &momento.TopicSubscribeRequest{
	CacheName: cacheName,
	TopicName: "test-topic",
})
if subErr != nil {
	panic(subErr)
}

time.Sleep(time.Second)
_, pubErr := topicClient.Publish(ctx, &momento.TopicPublishRequest{
	CacheName: cacheName,
	TopicName: "test-topic",
	Value:     momento.String("test-message"),
})
if pubErr != nil {
	panic(pubErr)
}
time.Sleep(time.Second)

// Receive only subscription items with messages
item, err := sub.Item(ctx)
if err != nil {
	panic(err)
}
switch msg := item.(type) {
case momento.String:
	fmt.Printf("received message as string: '%v'\n", msg)
case momento.Bytes:
	fmt.Printf("received message as bytes: '%v'\n", msg)
}

// Receive all subscription events (messages, discontinuities, heartbeats)
event, err := sub.Event(ctx)
if err != nil {
	panic(err)
}
switch e := event.(type) {
case momento.TopicHeartbeat:
	fmt.Printf("received heartbeat\n")
case momento.TopicDiscontinuity:
	fmt.Printf("received discontinuity\n")
case momento.TopicItem:
	fmt.Printf(
		"received message with sequence number %d and publisher id %s: %v \n",
		e.GetTopicSequenceNumber(),
		e.GetPublisherId(),
		e.GetValue(),
	)
}

Running the code​

You can find complete, working examples in the Go SDK GitHub repo examples directory.

info

Beyond these basic API calls check out the API reference page for more information on the full assortment of Momento API calls.