###### Abstract  
Domain-Specific Languages with JSON grammar (JSON-DSLs) are specialized programming languages tailored to specific problem domains, offering higher abstraction levels and simplifying software implementation through the JSON standard. RhoArchitecture is an approach for designing and executing JSON-DSLs, incorporating a modular programming model, a JSON-based evaluation engine, and an integrated web development environment. This paper presents RestRho, a RESTful NodeJS server developed using two JSON-DSLs designed with RhoArchitecture: SQLRho and DBRestRho. These languages enable declarative specification of database operations and HTTP requests, respectively, supporting modularity, reuse, and template-based transformations. We validate the RestRho implementation through a dual approach. First, we apply software metrics to assess code quality, maintainability, and complexity. Second, we conduct an empirical study involving 39 final-year computer engineering students, who completed 18 structured tasks and provided feedback via questionnaires. The results demonstrate the tool's usability, development efficiency, and potential for adoption in web application development. domain-specific languages; JSON; JSON-DSL; API RESTful; Rho architecture; templates engine +
Footnote †: journal:  
0000-0001-9991-4880-3331-331  
DSLs can be classified into Textual DSLs and Visual DSLs, according to [1; 7; 8]. In turn, Textual DSLs can be further categorized as follows: (i) DSLs with open text grammar focused on the domain context, (ii) DSLs with XML grammar (DSL-XML) based on the XML standard [9], and finally, (iii) DSLs with JSON grammar, under the JSON standard (JSON-LD, JSON for Linked Data) [10; 11]. Within this last classification, RhoA Architecture [12] allows designing, implementing, deploying, and running DSL solutions that use JSON grammar (JSON-DSL) for web applications on both the client and the server side. However, although the RhoA Architecture was rigorously evaluated [12], no validation was conducted on the solutions implemented and deployed with this approach. This validation is essential to ensure that the solutions are practical and beneficial in real-world applications. Regarding the quality of DSLs, different quality features can be assessed, such as expressiveness, flexibility, productivity, reusability, reliability, learnability, ease of maintenance, or usability [13]. This last feature, the usability of DSLs, is an important consideration for their adoption by domain experts [14], defined as the _\"extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use\"_[15]. The usability of DSLs is related to some of the advantages associated with their adoption, such as the abstraction of the technical details of the system [16], the ease of understanding [17], or the reduction in code writing. [PERSON] et al. [18] performed an empirical evaluation of the improved effectiveness and efficiency of using DSLs versus using general purpose languages (GPLs). Their goal was to determine whether using a DSL is more effective than writing all the code and whether the results were of comparable quality. Thus, the objective of the present article is to detail the evaluation performed on RhoArchitecture through a specific case study we called RestRho, a domain-specific solution that facilitates the specification, implementation, and deployment of RESTful (Representational State Transfer) APIs on a NodeJS [19; 20]. We performed the evaluation from two main points of view. Firstly, a software metrics-based validation of the implementation provided an objective assessment of the software quality. This included evaluating complexity, difficulty, effort, estimated errors, and maintainability [21].