7e5abd504f
Add three DBOS SDK skills with reference documentation for building reliable, fault-tolerant applications with durable workflows. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
70 lines
2.3 KiB
Markdown
70 lines
2.3 KiB
Markdown
---
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title: Use Events for Workflow Status Publishing
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impact: MEDIUM
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impactDescription: Enables real-time progress monitoring and interactive workflows
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tags: communication, events, status, key-value
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---
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## Use Events for Workflow Status Publishing
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Workflows can publish events (key-value pairs) with `dbos.SetEvent`. Other code can read events with `dbos.GetEvent`. Events are persisted and useful for real-time progress monitoring.
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**Incorrect (using external state for progress):**
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```go
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var progress int // Global variable - not durable!
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func processData(ctx dbos.DBOSContext, input string) (string, error) {
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progress = 50 // Not persisted, lost on restart
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return input, nil
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}
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```
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**Correct (using events):**
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```go
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func processData(ctx dbos.DBOSContext, input string) (string, error) {
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dbos.SetEvent(ctx, "status", "processing")
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_, err := dbos.RunAsStep(ctx, stepOne, dbos.WithStepName("stepOne"))
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if err != nil {
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return "", err
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}
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dbos.SetEvent(ctx, "progress", 50)
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_, err = dbos.RunAsStep(ctx, stepTwo, dbos.WithStepName("stepTwo"))
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if err != nil {
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return "", err
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}
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dbos.SetEvent(ctx, "progress", 100)
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dbos.SetEvent(ctx, "status", "complete")
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return "done", nil
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}
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// Read events from outside the workflow
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status, err := dbos.GetEvent[string](ctx, workflowID, "status", 60*time.Second)
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progress, err := dbos.GetEvent[int](ctx, workflowID, "progress", 60*time.Second)
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```
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Events are useful for interactive workflows. For example, a checkout workflow can publish a payment URL for the caller to redirect to:
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```go
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func checkoutWorkflow(ctx dbos.DBOSContext, order Order) (string, error) {
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paymentURL, err := dbos.RunAsStep(ctx, func(ctx context.Context) (string, error) {
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return createPayment(order)
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}, dbos.WithStepName("createPayment"))
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if err != nil {
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return "", err
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}
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dbos.SetEvent(ctx, "paymentURL", paymentURL)
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// Continue processing...
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return "success", nil
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}
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// HTTP handler starts workflow and reads the payment URL
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handle, _ := dbos.RunWorkflow(ctx, checkoutWorkflow, order)
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url, _ := dbos.GetEvent[string](ctx, handle.GetWorkflowID(), "paymentURL", 300*time.Second)
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```
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`GetEvent` blocks until the event is set or the timeout expires. It returns the zero value of the type if the timeout is reached.
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Reference: [Workflow Events](https://docs.dbos.dev/golang/tutorials/workflow-communication#workflow-events)
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