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Build E-Commerce Apps with Reactive Programming in Spring Boot

Reading Operation Data: Persistent

Explore how to implement persistent storage for Spring Boot Actuator HTTP trace data using a custom wrapper and Spring Data MongoDB. Understand the need for immutable object handling with Spring Data converters, repository customization, and how to register these components. This lesson helps you grasp practical methods for monitoring and managing operation data in reactive Spring Boot applications.

We'll cover the following...

Adding wrapper class

Spring Boot Actuator’s HttpTraceRepository stores’ instances of the HttpTrace class. Unfortunately, that record doesn’t have a proper key. This means we can’t save it directly into MongoDB. To handle this, and considering the fact that HttpTrace is final and not extendable, we must define a wrapper.

Java
public class HttpTraceWrapper {
    private @Id String id; //1
    private HttpTrace httpTrace; //2
    public HttpTraceWrapper(HttpTrace httpTrace) { //3
        this.httpTrace = httpTrace;
    }
    public HttpTrace getHttpTrace() { //4
        return httpTrace;
    }
}
Wrapper class used to store HttpTrace objects in MongoDB
  1. In line 2, the wrapper contains a string-based id with Spring Data Commons’ @Id annotation applied. This allows each instance to be uniquely identified.
  2. In line 3, an actual HttpTrace instance is contained in the wrapper.
  3. In line 4, we need a constructor call that accepts an existing HttpTrace object. The id is null so that Spring Data MongoDB creates a new, unique key.
  4. In line 7, a getter is needed to extract the HttpTrace object when retrieving.

We know that we must also define a corresponding Spring Data repository to store and retrieve HttpTraceWrapper objects from our MongoDB server.

Should this repository use the same Reactive Streams tactics we’ve used so far?

The answer to this is no, because HttpTraceRepository ...