Define an Activity - Go SDK

Activities do the work in your Temporal application. They’re Go functions that can run any code, including API calls, file operations, or database queries.

Write a basic Activity function

An Activity is a function that accepts a context.Context and returns an error, or a value and an error.

func MyActivity(ctx context.Context) error {
    // Perform work here
    return nil
}

Register the Activity with your Worker:

worker.RegisterActivity(MyActivity)

Pass parameters to an Activity

You can pass any serializable value. Use a struct to allow the function signature to evolve over time.

type MyActivityInput struct {
    ProductID string
    Quantity  int
}

func MyActivity(ctx context.Context, input MyActivityInput) error {
    // Use input.ProductID and input.Quantity
    return nil
}

Return results from an Activity

Return a custom struct if the result has multiple fields.

type MyActivityResult struct {
    Success bool
    ID      string
}

func MyActivity(ctx context.Context, input MyActivityInput) (*MyActivityResult, error) {
    return &MyActivityResult{
        Success: true,
        ID:      "order-123",
    }, nil
}

Group related Activities with a struct

You can define Activities as struct methods when they share setup or dependencies, like a database client.

type InventoryService struct {
    DBClient *MyDBClient
}

func (s *InventoryService) ReserveStock(ctx context.Context, input MyActivityInput) error {
    // Use s.DBClient
    return nil
}

Register the whole struct with the Worker:

inventory := &InventoryService{DBClient: myClient}
worker.RegisterActivity(inventory)

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Once your Activities are defined and registered, you can call them from inside a Workflow. Next, you’ll run a Worker to execute Workflows and Activities.