How can you manage stateful operations in serverless applications?

1 What is state and why does it matter?

State is any information that persists or changes over time in an application. For example, a user's login status, preferences, or history are stateful data that need to be stored and accessed across multiple requests. State also includes the progress of a long-running or complex operation, such as a payment process, a data analysis, or a workflow. State matters because it affects the functionality, performance, and security of your application. If you lose or corrupt state, you may cause errors, delays, or breaches in your application.

3 How can you store state in serverless applications?

One of the most common and recommended ways to store state in serverless applications is to use external services, such as databases, key-value stores, or message queues. These services can provide durable, consistent, and scalable storage for stateful data, and can be accessed by multiple functions or clients. For example, you can use AWS DynamoDB, a fully managed NoSQL database, to store user profiles, preferences, or session tokens. You can also use AWS S3, a highly available object storage service, to store files, images, or videos. Alternatively, you can use AWS SQS, a distributed message queue service, to store messages, events, or tasks that need to be processed by functions.

4 How can you access state in serverless applications?

State in serverless applications can be a challenge to access efficiently and securely. To minimize latency and overhead of connecting to external services, as well as ensure functions have the correct permissions and encryption, some best practices include connection pooling and reuse techniques, caching techniques, and secure and encrypted communication protocols. For example, you can use AWS Lambda's environment variables or global variables to store and reuse connections across invocations, AWS ElastiCache for caching frequently accessed or read-only data, and AWS KMS for encryption and decryption of your data at rest and in transit.

5 How can you orchestrate state in serverless applications?

The final challenge of state in serverless applications is how to orchestrate stateful operations or workflows that involve multiple functions or steps, such as a checkout process, a data pipeline, or a business logic. To manage the state transitions, dependencies, and retries of your functions, you can use AWS Step Functions to create state machines that define and execute your workflows. It allows you to invoke, monitor, and coordinate your functions, as well as handle errors, timeouts, and retries. Additionally, you can use AWS EventBridge to connect your functions with other AWS services or third-party applications. This event bus service lets you trigger your functions based on events and route, filter, and transform your events. Alternatively, you can use custom logic or libraries within your functions to implement your workflows. You can use conditional statements, loops, or callbacks to control the flow of your functions and external services to store and track the state of your workflows. Moreover, libraries such as AWS SDK or AWS X-Ray can be used to interact with other AWS services or monitor your functions.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?