Get Your Message Across: 3 Patterns for Modern Cloud Application Orchestration

Are you ready to dive into the world of asynchronous communication patterns?

If you're a developer or just someone interested in the technical aspects of modern applications, then you've come to the right place. In this article, we'll explore three different patterns - the Asynchronous Request Replay Pattern, Publisher-Subscriber Pattern, and Competing Consumers Pattern - that are commonly used in distributed systems.

But don't worry if you're not familiar with these concepts yet. By the end of this article, you'll have a solid understanding of what these patterns are, when to use them, and when to avoid them. So buckle up, grab your favorite drink, and let's get started!

Let's start with the "Asynchronous Request Replay Pattern." In simple terms, it's a way for client-side code to interact with remote APIs.

It's perfect for web-client applications because it allows you to initiate long-running actions on the backend without the need for callback endpoints or long-running connections.

Here's how it works:

• The client sends a synchronous request to the API.
• The API returns an HTTP 202 (Accepted) response code, indicating that the request is being processed.
• The response contains a location reference pointing to an endpoint that the client can poll to see the outcome of the lengthy operation.
• The processing is offloaded to another component, such as a message queue, through the API.
• When the task is finished, the status endpoint can either return a completion resource or redirect to another resource URL.

This pattern is great for browser apps, service calls using only HTTP, and legacy architectures that lack current callback technologies.

Now let's talk about the "Publisher-Subscriber Pattern." This pattern is all about creating an asynchronous messaging subsystem that allows the sender to package events into messages and send them via an input channel.

Consumers, also known as "subscribers," have output message channels, and an intermediary such as a message broker or event bus handles the replication of each message to all subscribers interested in that message.

Here's what you need to know:

• Consumers must be able to subscribe and unsubscribe from various channels through the messaging infrastructure.
• Connecting to any communication channel must be controlled by security policy.
• This pattern is great for applications that need to broadcast information to a large number of users, interact with independently produced applications or services, or deliver data to several consumers.

Next up, we have the "Competing Consumers Pattern." This pattern is ideal for cloud-based applications that need to manage a large number of requests.

Rather than processing each request synchronously, the application routes them through a message system to another service (a consumer service) that handles them asynchronously.

Here's what you need to know:

• Multiple instances of the consumer service must be coordinated so that each message is only provided to a single consumer.
• To avoid one instance from becoming a bottleneck, the workload must be distributed among consumers.
• This pattern is great for applications that need to process a varying workload and ensure that the business logic is not slowed down while the requests are being processed.

In conclusion, the Asynchronous Request Replay Pattern, Publisher-Subscriber Pattern, and Competing Consumers Pattern offer powerful solutions for modern application development.

By leveraging these patterns, developers can create highly scalable and efficient systems that can handle varying workloads and deliver information to multiple consumers. While each pattern has its strengths and weaknesses, they all have the potential to make a significant impact on the performance and functionality of applications.

So go forth and use these patterns to create cool, innovative, and high-performing applications that will impress and delight your users!