# A Comparative Assessment of JVM Frameworks to Develop Microservices
## 2 Background
As these three areas are crucial for implementing IoT and web services interoperability, therefore the authors of this article will evaluate selected JVM frameworks focusing mainly on them. In order to evaluate and compare the performance of given technologies, it is necessary to test them in a controlled runtime environment based on identical workloads generated by either a ready-made sample application or an application developed specifically for testing. This is the approach taken in this article, as well as in related articles to the research presented here. There have already been conducted a scientific comparative analysis of the Java ecosystem frameworks [22] (specifically Spring Boot and Play) around the above-mentioned three axes. However, the authors there did not focus on applications for building microservices, but for web apps and the results they obtained do not clearly indicate a winner. On the other hand, published research conducted in 2020 on new, but already well-established, solutions [23]--Quarkus and GraalVM--is largely descriptive, and its benchmarking part (using Renaissance Suit), focuses mainly on computing load, leaving out communication and database access aspects. The results obtained by the authors are promising for the GraalVM solution, and the authors propose to start using this platform in production environments. Empirical studies related to so-called green computing, that is, among other things, the energy efficiency of computing, are also being undertaken. In the case of the Java ecosystem, tests have been conducted for various benchmark applications with and without the use of the Spring framework [24]. The results clearly show the benefits of using the Spring framework. It may also be interesting to ask whether a microservice architecture applied to solutions that do not require auto-scaling will bring any advantages over a traditional monolithic architecture. This was tested by the authors [25] who studied the Spring Boot framework in this application, and the results indicate that with expected low application load, it may not make sense to go for the microservices approach, as the gain, if any, may be small, while the complexity of building a microservices solution is always higher. In another study, the authors [26] ask themselves about the performance of technologies for synchronous and asynchronous communication between microservices. Their results suggest that under light load synchronous communication is sufficient, while when a fixed number of microservice instances can no longer handle the traffic it is worth reaching for queuing mechanisms. However, the question may arise--why not take advantage of the possibility of scaling by increasing the number of instances in such a case? In addition, the authors do not specify what technology was used to implement synchronous communication and whether it was based on a reactive or blocking approach. Finally, the authors of a 2020 article titled \"Implementation of the Internet of Things Application Based on Spring Boot Microservices and REST Architecture\" [27] demonstrated their proof-of-concept solution and argued that the Spring Boot framework is particularly useful for implementing modern IoT solutions. Moreover, a recent paper by [PERSON] et al. [28] touches on the performance topics of the application frameworks studied in this article (i.e., Spring Boot, Quarkus and Micronaut frameworks). However, the authors of that paper used the ready-made application as the subject of their performance research and did not look individually at the performance of the individual component mechanisms of typical microservices applications, such as the communication layer, the data layer or the computation layer. Findings of the two works mentioned above, confirming the suitability of Java Spring Boot framework to implement microservices, together with the constant evolvement of direct competitors of Spring Boot (such as Quarkus or Micronaut) have generated the authors' motivation to undertake studies on this topic.