IBX-7057: Provided Notifications API

[webhdx]

Question	Answer
JIRA issue	IBX-7057
Type	feature
Target eZ Platform version	v4.6
BC breaks	no
Doc needed	yes

NotificationService

It's the core of this feature. It exposes PHP API for sending system and user notifications. It uses symfony/notifier internally but I provided our own abstraction just in case. It offers great flexibility on how Notifications can be delivered. We can route all Admin UI flash messages via specific Notifications API channel and make them appear in the browser OR let users decide if they want specific Admin notification to be also delivered to Slack or e-mail.

Symfony Notifier can also take advantage of the Message Bus and we can send notifications asynchronously, unblocking requests from dealing with SMTP servers or APIs.

ChannelSubscription and SubscriptionResolver

Since we want to offer flexibility and we have a few notification channels already, I made a simple configuration to decide which Notification goes where. Configuration should be only used for system notifications or things from which the user can't opt out. I assume in the future we'll let users subscribe to only specific types of notifications. This is where ChainSubscriptionResolver comes into place - it can resolve subscriptions from multiple resolvers. I have different data sources in mind - i.e. there will be a new Resolver reading subscriptions from User Preferences.

Example configuration

ibexa:
    system:
        default:
            notifications:
                subscriptions:
                    Ibexa\Notifications\Value\Notification\OrderConfirmationNotification:
                        channels:
                            - actito

The configuration is siteaccess aware and single notification can be routed to multiple channels.

Checklist:

• Provided PR description.
• Tested the solution manually.
• Provided automated test coverage.
• Checked that target branch is set correctly (master for features, the oldest supported for bugs).
• Asked for a review (ping @ibexa/engineering).