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Most modern software is designed specifically for use in distributed systems. Coordinating various services and applications usually achieves a seamless experience for the end-user in these systems. However, because of the interrelated structure of multiple services and applications, pinpointing the source of a problem when anything goes wrong can take time and effort. This is where correlation ID comes into play.

In this post, we will explore correlation IDs, how they work, and the best practices for their use in distributed systems. Keep reading!

What Is Correlation ID and How Does It Work?

A correlation ID is a randomly generated identifier for every request entering a distributed system. Developers use the correlation identifier to trace the request as it makes its way through the system, identify any cyber security threats, and prevent them.

The correlation ID basically serves as a thread that connects the various parts of a request as it moves through the system. This greatly simplifies distributed system debugging and troubleshooting by allowing developers to track a request’s progress and readily pinpoint the service or component where an issue occurred.

For instance, think of a simple distributed system with three services: a web server, an application server, and a database server. When a user makes a request, a unique correlation ID is usually given and attached to each request sent to a web server. The web server sends the request and the correlation ID to the application server. The request is received at the application server, which adds the correlation ID and sends it to the database server. Lastly, the database server receives the request along with the correlation ID and then works on it.

Why Is Correlation ID Important in Distributed Systems?

As mentioned earlier, requests can move through different services or components, making it difficult to determine the request’s path or pinpoint the particular component or service where an error occurs.

By assigning a unique correlation ID to each request and sending it along to each service or component that deals with requests, developers can conveniently monitor the progress of the request. When an error occurs in a component, it’s easy to group related transactions and detect the root cause of the issue. Because of this, debugging and troubleshooting distributed systems becomes simple.

Without a correlation ID, developers would have to spend much time and make errors trying to piece together a request’s path through the system. Correlation ID improves the process by assigning a unique identifier to each request, which can then be used to track the request as it makes its way through the system.

Correlation ID can also enhance system performance by allowing developers to monitor performance metrics for individual requests. This can help identify bottlenecks or potential improvement targets to enhance the system’s performance.

What Are the Best Practices for Implementing Correlation ID?

Implementing correlation ID in a distributed system is a best practice that can greatly enhance the capacity to diagnose and troubleshoot issues. However, you must follow several guidelines to implement the correlation ID successfully. Here are some of the best practices:

1. Generate Unique Identifiers

Each request sent to the system must have a unique correlation ID. Developers can generate unique correlation identifiers using time stamps and random numbers.

2. Include the Identifier in All Logs

Each service or component that processes a request should include the correlation ID in its logs. This ensures that all logs related to a certain request can be easily identified and connected.

3. Propagate the Identifier Across All Services

All subsequent services or components that deal with the request should be aware of the correlation ID. This ensures that the request has a unique identifier that can be associated with each service or component.

4. Use Standard Formats

Developers should adopt standardised formats for correlation IDs to ensure consistency across all services and components. This makes it easier to find and correlate logs related to a certain request and see how they connect.

5. Monitor and Analyse Correlation IDs

Correlation identifiers should be tracked and analysed to identify recurring patterns and anomalies. This can help identify bottlenecks or potential improvement targets to enhance the system’s performance.

6. Implement Automated Tracing

Automated tracing can be implemented to trace the path of a request through the distributed system using correlation identifiers. This can make diagnosing and troubleshooting easier by providing a visual picture of the request’s path.

Practical Instances of How to Implement Correlation IDs

Correlation identifiers are usually used to track a particular transaction or request as several systems and components process it. Here are some practical instances of how to implement correlation IDs:

1. HTTP Request

In a distributed system that uses HTTP requests to communicate between services, you can add a correlation ID to the HTTP header of every request. One way of doing this is using middleware or an interceptor that creates and appends a meaningful unique identifier to the header. Each service in the distributed system can record or log the correlation ID with any related messages, making it easier to track an HTTP request as it moves through the system.

2. Logging

When logging messages from various services and components, include the correlation identifier. You can do this by passing the correlation ID in the log message or using a logging library that does so automatically.

3. Messaging Systems

Using a messaging system like RabbitMQ or Kafka, you can include the correlation identifier as a message header. This can help track messages moving through multiple components and services and be handy for troubleshooting.

4. Microservices Architecture

In a microservices architecture, every service can create its correlation ID and pass it along to downstream services. This can be done using an interceptor or middleware that adds the correlation identifier to every request or message.

5. Cloud-Based Systems

In a cloud-based system, you can use a tool such as AWS X-Ray to track incoming requests as they move through multiple services and components. The X-Ray automatically generates correlation IDs for each request and can provide detailed tracing and debugging data.


Correlation ID is crucial in distributed systems since it can substantially simplify debugging and troubleshooting. Besides, correlation ID makes it simple to track the path of an incoming request and compare logs from various services by generating a unique identifier for it and then propagating it elsewhere. This can help identify and resolve issues during request header processing, enhancing system performance and user experience.

To ensure the effective implementation of correlation IDs, developers should follow the best practices such as generating unique identifiers, including the identifier in all logs, propagating the identifier across all services, by security monitoring and analysing correlation IDs, as well as implementing automated tracing.

Frequently Asked Questions on Correlation ID

1. How does correlation ID improve system performance?

By allowing developers to track performance metrics for individual requests, correlation identifiers can help identify bottlenecks or potential improvement targets to improve the system’s overall performance.

2. How do you find a correlation identifier?

Here is an example of a correlation ID: 9d2dee33-7803-485a-a2b1-2c7538e597ee. You can make API calls or use network logs to find your correlation ID.

3. What’s a correlation identifier in a message broker?

A correlation identifier is often included in the header of a message. The ID has nothing to do with the data or command sent to the recipient. The receiver usually saves the ID from the request and includes it in the reply for the caller’s benefit.

4. What’s 0x80004005’s correlation ID?

A Microsoft 365 error code of 0x80004005 indicates that you don’t have Microsoft 365 or an Office 365 plant that includes Microsoft 365 apps. It’s also possible that the current subscription has expired. The 0x80004005 issue might be related to a single user for whom every Microsoft 365 app results in an error.

5. Is correlation ID a UUID?

The format for Correlation ID might be a universally unique identifier (UUID) or anything else relevant in the context of the web firewall application domain that secures online applications. Trendyol usually uses UUIDs as correlation identifiers. Conversely, X-correlated-id is an X-correlated-identified HTTP header with no standard identifiers or correlations.

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