AWS Step Functions Express vs. Standard Workflows: Which One Fits Your Use Case?

AWS Step Functions is a fully managed service that allows you to build serverless workflows to coordinate AWS services and applications. Step Functions offers two different workflow types: Express Workflows and Standard Workflows. These workflow types are designed to cater to different use cases and requirements. 

In this article, we will explore the key differences between Express and Standard Workflows and when you should choose one over the other.

Express Workflows

What are Express Workflows?

Express Workflows are a new type of AWS Step Functions workflow designed for high-throughput, low-latency use cases. They are optimised for rapid execution and are ideal for scenarios where you need to process a large number of short-duration tasks quickly.

Key Characteristics of Express Workflows

1. Rapid Execution: Express Workflows are designed for fast execution, with the ability to initiate and complete thousands of workflow executions per second.

2. Simplified Billing: Express Workflows offer a simplified pricing model based on the number of state transitions and parallel executions, making it cost-effective for high-throughput workloads.

3. Short-lived: Express Workflows are best suited for workflows that typically complete in seconds or a few minutes. They are not intended for long-running workflows.

4. Limited State Capacity: Express Workflows have a limited state history and no state history retention, which means they are not suitable for workflows that require extensive state tracking.

5. No Callback Support: Express Workflows do not support callback patterns, so they may not be the best choice for workflows that require asynchronous communication with external systems.

Standard Workflows

What are Standard Workflows?

Standard Workflows are the original AWS Step Functions workflow type and offer a broader range of capabilities compared to Express Workflows. They are designed for complex, long-running workflows with features like state history tracking and callback support.

Key Characteristics of Standard Workflows

1. Complex Workflows: Standard Workflows are suitable for workflows that involve complex decision logic, error handling, and long-running tasks. They can also handle workflows with human interaction via AWS Lambda functions.

2. State History: Standard Workflows retain the entire state history of a workflow, allowing you to review and analyse past executions, which can be valuable for debugging and auditing.

3. Callback Support: Standard Workflows support callback patterns, making them a good choice for workflows that require asynchronous communication with external systems.

4. Parallelism Control: Standard Workflows offer fine-grained control over parallelism, allowing you to specify the maximum number of concurrent tasks for each state.

5. Long-lived: Standard Workflows can run for hours, days, or even months, making them suitable for a wide range of use cases, including orchestration of complex business processes.

Choosing Between Express and Standard Workflows

The choice between Express and Standard Workflows depends on your specific requirements and use case:

Choose Express Workflows If:

 1. You need to process a high volume of short-duration tasks quickly.

 2. Cost-effectiveness and rapid execution are your top priorities.

 3. Your workflow is short-lived and doesn't require extensive state tracking.

Choose Standard Workflows If:

 1. Your workflow is complex, with branching logic, error handling, or long-running tasks.

 2. You need to retain and review the entire state history of workflow executions.

 3. Callback support for asynchronous communication is essential.

 4. Your workflow can run for an extended period, potentially spanning hours, days, or months.

Conclusion

In summary, AWS Step Functions offers both Express and Standard Workflows to cater to a wide range of use cases. Your choice should be based on your specific workflow requirements, with Express Workflows optimised for speed and cost-effectiveness, while Standard Workflows offer more features and flexibility for complex and long-running workflows. Carefully evaluate your workflow's needs to make the right choice and maximise the benefits of AWS Step Functions.

Remember that AWS services and features may evolve, so always refer to the official AWS documentation and release notes for the most up-to-date information on Step Functions and its capabilities.