65 lines
1.8 KiB
Plaintext
65 lines
1.8 KiB
Plaintext
# pkg/eventbus
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Package handles event dispatching and handler registration
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## Event
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Event (in context of eventbus package) contains of resource type, event type and a matcher.
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### Resource type
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Resource types are identifiers of internal resources, like user, role, request, ...
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### Event type
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Type describes direct or indirect user action or some other event in the system.
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#### Deferred events
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Deferred events (onTimestamp and onInterval) are executed by scheduler package service.
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#### Manual events
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Manual events (onManual) are a special case.
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These events are not (nor should be) dispatched directly or through event-bus.
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We use it to route requests and pack attributes from the API to the Corredor service
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### Event matcher
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Matcher is a function on event that helps filtering fired events.
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It decides (returns true or false) if fired event is a match for any of a registered handlers
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Bus has basic internal filtering for resource & event type.
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Other constraints are passed to event's matcher function.
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.Matcher will receive 2+ string parameters:
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- name
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- operator
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- zero or more values
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It's matcher responsibility to handle contents of name, operator and values parameters.
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Constraint checker procedure will call matcher for each constraint.
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All constraints must match.
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First non-match will break constraint checking procedure.
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## Handler
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Handler is combination of (event matching) rules/constraints and handler callback function.
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Function is called when a event compatible with registered rules & constraints is fired.
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Handler can respond to multiple resource/event combinations.
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### Constraints
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Matcher function is called multiple times, once per each handler constraint.
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If any of the calls result in a non-match, check
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Handler without any constraints is considered a match.
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### Weight
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Weight controls order of execution.
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