Async APIs are key components of event-driven architectures and systems. However, they add complexity, making them difficult to manage once deployed.
For example, asynchronous communication doesn’t always occur in order or within a short timeframe, leading to messages returning out of order. If the server fails to respond, the system may lose messages it should have sent, or it may not send alerts about response failures. These problems can lead to utter confusion if not appropriately managed by development teams!
This article helps you navigate the complexity by showing how the right API tools and DevOps methods can simplify designing and building async APIs.
Start with an API specification — or two
An API specification is essential in developing an asynchronous API (or any API!). It helps you establish ground rules like:
- How your API will function and behave
- How it can link with other APIs
- What results to expect when using it
OpenAPI is the most widely used API specification. Developers use OpenAPI to create better API documentation, automate processes, and improve collaboration. You’ll benefit from using OpenAPI for your async APIs and even more if you use it alongside AsyncAPI.
AsyncAPI started as an adaptation of OpenAPI for building message-based architectures. Today, it’s an open source initiative to make working with asynchronous APIs and event-driven architectures (EDAs) as easy as working with REST APIs.
APIs, AsyncAPI and OpenAPI serve different but complementary purposes. OpenAPI is used primarily to describe HTTP APIs and REST API interactions. AsyncAPI focuses on message-based APIs and architectures — it’s protocol-agnostic and works well with various communication protocols, such as AMQP, MQTT, and WebSockets.
You can provide a broad view of your entire API system by using OpenAPI to define REST interactions and AsyncAPI to define services communication.
Next, implement API management tools
The lifecycle of an async API is different from that of a synchronous API. There are fewer opportunities to change things once you release an async API to a larger event-driven system. This has ripple effects throughout the lifecycle of the API and the architecture. So look for a platform that has async API management capabilities, such as:
- Authentication and authorization — The platform should support multiple authentication methods, such as basic, OAuth 2.0, and JSON Web Token (JWT). It should let you control API access based on user roles and policies, with the option of granular permissions for specific topics, events, or message types.
- Transformation and enrichment — Async APIs often deliver messages and event types. Find a platform that can convert between data formats, such as JSON to XML or CSV to JSON. It should also let you enrich messages with additional data from external sources, like a database or data streams.
- Monitoring and analytics — You need comprehensive monitoring and analytics capabilities to gain visibility into the health of your async APIs and the entire EDA. These tools are essential to debug security issues and optimize the performance of your async APIs. Look for a platform that can track various metrics, including performance, usage, latency, error counts, and message rates.
These capabilities help you ensure your async APIs perform well and remain secure.
Consider using an API gateway to help implement capabilities like authentication and authorization, rate limiting, load balancing, and protocol translation. You can also use an API gateway to set up timeouts and automatic retries for API calls.
Once you have tools to manage your async APIs, the next stop is DevOps.
DevOps practices for async APIs
DevOps involves implementing best practices, team collaboration, and automation to speed up and improve software development.
You can apply many of the same DevOps best practices for synchronous APIs to asynchronous APIs, which is fortunate since many microservices architectures include both.
General practices for APIs include:
- Security: Applying DevOps practices to your APIs helps ensure they remain secure even after deployment. Standardize security practices by using an API specification during the design process and automating security processes.
- Testing: Automate as many testing processes as possible, running tests early and often within your continuous integration/continuous deployment (CI/CD) pipeline (shift-left testing).
- Monitoring: Continuous monitoring ensures the health of APIs, applications, and systems. You should perform API health checks on a rolling basis, monitoring everything from availability and functionality to load and performance.
- Scaling: Async APIs typically power EDAs, which tend to become large and complex, requiring collaboration and automation to ensure scalability. DevOps practices can also help with scaling synchronous APIs.
You’ll need to adjust these practices to accommodate the non-blocking and decoupled nature of async APIs. The table below shows how the application of DevOps differs between synchronous and asynchronous APIs.
DevOps practices: synchronous vs. asynchronous APIs
| Synchronous APIs | Asynchronous APIs | |
| Security | Focus primarily on individual endpoints, securing them with measures such as authentication and authorization. | Take additional measures, such as protecting message queues and event streams with encryption and access control. |
| Testing | Focus on individual endpoints and request-response patterns using standard testing methods. | Consider events and message handling. Include additional testing methods to check eventual consistency, retry mechanisms, and message delivery. |
| Monitoring | Monitoring is straightforward — base your approach on request-response cycles. Common metrics include availability, latency, throughput, and error rates. | Async APIs require more complex monitoring approaches. Consider message-related metrics such as message queue sizes and message processing speed. |
| Scaling | Use automated tools to scale synchronous APIs horizontally based on request volume. | Use automated tools to scale consumers and producers independently — scale based on message queue capacity, backlog, or throughput. |
A reliable API management platform and an API gateway can help you implement and follow these DevOps practices.
Build better async APIs with proper tools and DevOps
Navigating the complexity of async APIs requires a strategic approach that combines API specifications, API management tools, and DevOps practices. This approach also helps developers design, build, and manage asynchronous APIs more efficiently (synchronous APIs, too!).
Async APIs are critical parts of event-driven architectures and systems, so it makes sense to adopt these tools and practices that ensure the reliability and consistency of APIs. All you need to do now is take that first step!
