snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

docs/content/pubsubs/bolt.md

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+title = "Bolt Pub/Sub"
+description = "A pure Go key/value store"
+date = 2021-11-19T00:00:00+02:00
+bref = "A pure Go key/value store"
+weight = 20
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+
+Bolt is a pure Go key/value store which provides a simple, fast, and reliable
+database for projects that don't require a full database server such as
+Postgres or MySQL.
+
+Bolt backed Pub/Sub is good for simple applications which don't need a more
+advanced Pub/Sub system with external dependencies or already use Bolt and
+want to publish messages in transaction when saving other data.
+
+Bolt documentation: https://github.com/etcd-io/bbolt
+
+## Installation
+
+```bash
+go get github.com/ThreeDotsLabs/watermill-bolt
+```
+
+### Characteristics
+
+| Feature             | Implements | Note |
+| ------------------- | ---------- | ---- |
+| ConsumerGroups      | no         |      |
+| ExactlyOnceDelivery | no         |      |
+| GuaranteedOrder     | no         |      |
+| Persistent          | yes        |      |
+
+### Configuration
+
+{{% load-snippet-partial file="src-link/watermill-bolt/pkg/bolt/bolt.go" first_line_contains="type CommonConfig struct " last_line_equals="}" %}}
+
+{{% load-snippet-partial file="src-link/watermill-bolt/pkg/bolt/bolt.go" first_line_contains="type PublisherConfig struct " last_line_equals="}" %}}
+
+{{% load-snippet-partial file="src-link/watermill-bolt/pkg/bolt/bolt.go" first_line_contains="type SubscriberConfig struct " last_line_equals="}" %}}
+
+#### Subscription name
+
+To receive messages published to a topic, you must create a subscription to
+that topic. Only messages published to the topic after the subscription is
+created will be received by the subscriber.
+
+A topic can have multiple subscriptions, but a given subscription belongs to
+a single topic.
+
+In Watermill, the subscription is created automatically during calling
+`Subscribe()`.  Subscription name is generated by calling the function set as
+`SubscriberConfig.GenerateSubscriptionName`.  By default, it is the topic name
+with the string `_sub` appended to it.
+
+#### Marshaler
+
+Watermill's messages cannot be directly saved in Bolt which operates on byte
+slices. Marshaller converts the messages to and from byte slices. The default
+implementation marshals messages as JSON, a format which is human-readable
+for easier debugging. The performance should be enough for most applications
+unless a very large messages are used within your system. If that is the case
+you may want to consider implementing a more efficient marshaler.
+
+{{% load-snippet-partial file="src-link/watermill-bolt/pkg/bolt/marshaler.go" first_line_contains="// Marshaler" last_line_equals="}" %}}