ballerina/workflow Ballerina library

Executes an activity function within the workflow context.

Activities are non-deterministic operations (I/O, database calls, external APIs) that should only be executed once during workflow execution and not during replay. The workflow runtime ensures exactly-once execution semantics for activities.

The return type is determined by the T typedesc parameter, allowing compile-time type checking when the expected return type is specified. The compiler plugin validates that the activity function's return type is compatible with T.

By default, if the activity function returns an error, it is treated as a failure and the engine will retry the activity based on the retry policy. To treat errors as normal completion values, set failOnError to false in the options.

Example:

// Basic activity call (errors cause failure + retry by default)
string result = check ctx->callActivity(sendEmailActivity, {email: recipientEmail, subject: subject});
// With custom retry policy
string result = check ctx->callActivity(sendEmailActivity, {email: recipientEmail}, 
    options = {retryPolicy: {maximumAttempts: 3, initialIntervalInSeconds: 2}});
// Treat errors as normal completion (no retry on error)
string|error result = ctx->callActivity(riskyActivity, {data: input}, options = {failOnError: false});

Durable sleep that survives workflow restarts.

Unlike regular sleep, this is persisted and will continue counting even if the workflow is replayed or the worker restarts.

Check if the workflow is currently replaying history.

Useful for skipping side effects that should only happen on first execution. For example, logging or metrics that shouldn't be duplicated during replay.

Get the unique workflow ID.

Get the workflow type name.