Correlation Identifier: Ensuring Traceability in Distributed Systems

Correlation identifier of requests-responses is an essential feature of microservice platforms for monitoring, reporting, debugging and diagnostics.
Allows tracing a single request inside the application flow, when it can often be dealt with by multiple downstream services.

Problem statement

The most trending direction in software development is distributing processing and systems. In software architectual system designs there are multiple service layouts: single monolithic systems, SOA distribution, and nowadays microservice level grouping of services, applications.
In case of multiple services, we should consider, even multiple running entities from one specific service.

In case of looking into the logs, we could have a harder time to track down the chain of calls and locate the specific instances, which was hit by the request, through serving a user request.

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Leveraging Server-Sent Events (SSE) with Spring WebFlux for Real-Time Data Streaming

Introduction

What options we have to gather long processing data from the backend to send out to the UI?
Usually the followings:

  • open frequent connections – polling
  • keep an open connection – websocket

Server Sent Events

With Server Sent Events you’re able to send continuous updates from the server.
Imagine as a client subscription to a server for a stream.
Sometimes we don’t need a full bi-directional protocol (sending data back from client side), just a non-blocking data flow with the ability to process data row by row, while still receiving from the connection.
These are updates, time splitted data chunks from the server side to provide a fluent UI experience.

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Enhancing Unit Testing with various Test Doubles

The topic tries to cover high level of Test Doubles, Mocks. Here we have many named concepts around, Fake, Mock, Spy, Stub, etc…

Testing with mocks, stubs is primarily happens with unit, integration testing.
In object oriented world, bigger or smaller units of codes are tested, and while we having SRP objects, we still have to deal with dependencies and other object structures while we processing code.
To clean cut and provide a stable state we’re should fix those parameters/dependencies, which are not in the question from the testing perspective.

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Multilevel-KeySearch – Solution for Complex Data Lookup Strategies

Why? What’s this all about?

This is a library to handle (store-search) multi level key attributes.
The implementation was driven by the need of

  • handle multiple level keys
  • flexible search
  • ranking/ordering

on the matches .

Lets consider data with multiple levels: category / subcategory / group / item levels for example.
If you want to find specific let’s say: subcategory, that’s an easy task. You can filter/map and you get it. But what if you have multiple attribute to match, multiple key lengths? How will you sort them? This task can be achieved, but requires more and more code and you lose fluency.

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Class-Method Caching: Boosting Performance in Java

When you have the need of caching that’s a quite common topic, you can find many out-of-the-box solutions.

But what if if you want to cache whole class, with all the methods, maybe across your whole application?
My solution based on a proxy class and this way applies cache on all method invocations. The cache configuration of course can be defined, but the basics can be seen in the example below:

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