41 lines
2.0 KiB
Markdown
41 lines
2.0 KiB
Markdown
+++
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title = "Implementing a new Pub/Sub"
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description = "Bring Your Own Pub/Sub"
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date = 2018-12-05T12:48:34+01:00
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weight = 200
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draft = false
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bref = "Bring Your Own Pub/Sub"
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+++
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## The Pub/Sub interface
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To add support for a custom Pub/Sub, you have to implement both `message.Publisher` and `message.Subscriber` interfaces.
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{{% load-snippet-partial file="src-link/message/pubsub.go" first_line_contains="type Publisher interface" last_line_contains="type SubscribeInitializer" padding_after="0" %}}
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## Testing
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Watermill provides [a set of test scenarios](https://github.com/ThreeDotsLabs/watermill/blob/master/pubsub/tests/test_pubsub.go)
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that any Pub/Sub implementation can use. Each test suite needs to declare what features it supports and how to construct a new Pub/Sub.
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These scenarios check both basic usage and more uncommon use cases. Stress tests are also included.
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## TODO list
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Here are a few things you shouldn't forget about:
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1. Logging (good messages and proper levels).
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2. Replaceable and configurable message marshaler.
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3. `Close()` implementation for the publisher and subscriber that is:
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- idempotent
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- working correctly even when the publisher or the subscriber is blocked (for example, waiting for an Ack).
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- working correctly when the subscriber output channel is blocked (because nothing is listening on it).
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4. `Ack()` **and** `Nack()` support for consumed messages.
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5. Redelivery on `Nack()` for a consumed message.
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6. Use [Universal Pub/Sub tests]({{< ref "/docs/pub-sub#universal-tests" >}}). For debugging tips, you should check [tests troubleshooting guide](/docs/troubleshooting/#debugging-pubsub-tests).
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7. Performance optimizations.
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8. GoDocs, [Markdown docs]({{< ref "/pubsubs" >}}) and [Getting Started examples](/learn/getting-started).
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We will also be thankful for submitting a [pull request](https://github.com/ThreeDotsLabs/watermill/pulls) with the new Pub/Sub implementation.
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If anything is not clear, feel free to use any of our [support channels]({{< ref "/support" >}}) to reach us, we will be glad to help.
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