68 lines
2.5 KiB
Go
68 lines
2.5 KiB
Go
// Package flow is a generic, JSON-configurable orchestration engine. A flow is a
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// sequence of named steps; each step runs a registered action, may be gated by a
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// registered predicate, can fire registered hooks (before/after/on-error), and
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// may declare a compensating action used to roll back on failure (the saga
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// pattern). Actions, predicates and hooks are registered by name — the same
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// "interface + interchangeable impls, wired in one place" seam the CMS uses for
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// its event listeners. The flow definition itself is plain JSON, so flows live
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// alongside the app's other JSON config (schemas, blueprints) and can be edited
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// without code changes.
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package flow
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import "encoding/json"
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// Definition is a whole flow, loadable from JSON.
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type Definition struct {
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Name string `json:"name"`
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Description string `json:"description,omitempty"`
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Steps []Step `json:"steps"`
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}
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// Step is one unit of work in a flow.
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type Step struct {
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// Name identifies the step in logs, hooks and results.
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Name string `json:"name"`
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// Action is the registered action to run.
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Action string `json:"action"`
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// Params is opaque JSON passed to the action.
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Params json.RawMessage `json:"params,omitempty"`
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// When, if set, names a registered predicate; the step is skipped when it
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// returns false.
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When string `json:"when,omitempty"`
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// Hooks fire around the action.
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Hooks Hooks `json:"hooks,omitempty"`
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// Compensate, if set, is the action used to undo this step when a later step
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// fails (executed in reverse order during rollback).
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Compensate *ActionRef `json:"compensate,omitempty"`
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// ContinueOnError records the error and proceeds instead of rolling back.
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ContinueOnError bool `json:"continueOnError,omitempty"`
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}
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// ActionRef names an action and its params (used for compensation).
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type ActionRef struct {
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Action string `json:"action"`
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Params json.RawMessage `json:"params,omitempty"`
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}
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// Hooks groups the hook references that fire at each phase of a step.
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type Hooks struct {
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Before []HookRef `json:"before,omitempty"`
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After []HookRef `json:"after,omitempty"`
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OnError []HookRef `json:"onError,omitempty"`
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}
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// HookRef names a registered hook and its params.
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type HookRef struct {
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Type string `json:"type"`
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Params json.RawMessage `json:"params,omitempty"`
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}
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// Parse loads a flow definition from JSON bytes.
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func Parse(data []byte) (*Definition, error) {
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var d Definition
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if err := json.Unmarshal(data, &d); err != nil {
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return nil, err
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}
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return &d, nil
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}
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