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php-event-pubsub

An event protocol and implementation over pub/sub

This library builds on top of the php-pubsub package and adds support for listening to and dispatching events over pub/sub channels.

Installation

Integrations

Want to get started quickly? Check out some of these integrations:

• Laravel - https://github.com/Superbalist/laravel-event-pubsub

Usage

Simple Events

A SimpleEvent is an event which takes a name and optional attributes.

Topic Events

A TopicEvent is an event which takes a topic, name, version and optional attributes.

Schema Events

A SchemaEvent is an extension of the TopicEvent and takes a schema and optional attributes. The topic, name and version are derived from the schema.

The schema must be in the format (protocol)://(......)?/events/(topic)/(channel)/(version).json

Custom Events

You can easily use a custom event structure by writing a class which implements the EventInterface interface. You will then need to write a custom translator to translate incoming messages to your own event object.

Your event must implement the following methods.

Translators

A translator is used to translate an incoming message into an event.

The package comes bundled with a SimpleEventMessageTranslator, TopicEventMessageTranslator and a SchemaEventMessageTranslator.

Custom Translators

You can easily write your own translator by implementing the MessageTranslatorInterface interface.

Your translator must implement the following methods.

Validators

A validator is an optional component used to validate an event upon dispatch.

JSONSchemaEventValidator

This package comes bundled with a JSONSchemaEventValidator which works with SchemaEvent type events.

This validator validates events against a JSON Schema Spec using the JSON Guard PHP package.

Please see the "Schema Events" section above and the JSON Guard documentation for usage examples.

Custom Validators

You can write your own validator by implementing the EventValidatorInterface interface.

Your validator must implement the following methods.

Attribute Injectors

An attribute injector allows you to have attributes automatically injected into events when events are dispatched.

The library comes bundled with a few injectors out of the box.

• DateAttributeInjector - injects a date key with an ISO 8601 date time
• GenericAttributeInjector - injects a custom key and value
• HostnameAttributeInjector - injects a hostname key with the server hostname
• Uuid4AttributeInjector - injects a uuid key with a UUID-4

You can write your own injector by implementing the AttributeInjectorInterface or by passing a callable (which returns an array with a 'key' and 'value') to the event manager.

Your injector must implement the following methods.

Here's a usage example demonstrating both a class and a callable.

Custom Class

Callable

Error Handling

The library supports error handlers for when event translation fails, listen expression fails and validation fails.

You can pass callables into the EventManager constructor, or set them as follows:

Examples

The library comes with Dockerfile for running the example scripts.

Run make up.

You will start at a bash prompt in the /opt/php-event-pubsub directory.

To run the examples: