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Fix reference to subscriber in pub-sub documentation and improve pub/sub documentation #657

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14 changes: 7 additions & 7 deletions docs/content/docs/pub-sub.md
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Expand Up @@ -13,8 +13,8 @@ bref = "Publishers and Subscribers"

### Publishing multiple messages

Most publishers implementations don't support atomic publishing of messages.
This means that if publishing one of the messages fails, the next messages won't be published.
Most publisher implementations don't support atomic publishing of messages.
This means that if publishing one of the messages fails, the remaining messages won't be published.

### Async publish

Expand All @@ -23,7 +23,7 @@ Publish can be synchronous or asynchronous - it depends on the implementation.
#### `Close()`

`Close` should flush unsent messages if the publisher is asynchronous.
**It is important to not forget to close the subscriber**. Otherwise you may lose some of the messages.
**It is important not to forget to close the publisher**. Otherwise you may lose some of the messages.

## Subscriber

Expand All @@ -36,16 +36,16 @@ A proper implementation should wait for an `Ack` or a `Nack` before consuming th

**Important Subscriber's implementation notice**:
Ack/offset to message's storage/broker **must** be sent after Ack from Watermill's message.
Otherwise there is a chance to lose messages if the process dies before the messages have been processed.
Otherwise there is a risk of losing messages if the process dies before the messages have been processed.

#### `Close()`

`Close` closes all subscriptions with their output channels and flushes offsets, etc. when needed.
`Close` shuts down all subscriptions, closes their output channels, and flushes offsets when needed.

## At-least-once delivery

Watermill is built with [at-least-once delivery](http://www.cloudcomputingpatterns.org/at_least_once_delivery/) semantics.
That means when some error occurs when processing a message and an Ack cannot be sent, the message will be redelivered.
This means that if an error occurs while processing a message and an Ack cannot be sent, the message will be redelivered.

You need to keep it in mind and build your application to be [idempotent](http://www.cloudcomputingpatterns.org/idempotent_processor/) or implement a deduplication mechanism.

Expand All @@ -54,7 +54,7 @@ Unfortunately, it's not possible to create a universal [*middleware*]({{< ref "/
## Universal tests

Every Pub/Sub is similar in most aspects.
To avoid implementing separate tests for every Pub/Sub, we've created a test suite which should be passed by any Pub/Sub
To avoid implementing separate tests for every Pub/Sub, we've created a test suite, which should be passed by any Pub/Sub
implementation.

These tests can be found in `pubsub/tests/test_pubsub.go`.
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