OBJECT-ORIENTED PROGRAMMING AS A CONTRACT BETWEEN BACKEND AND MOBILE APPLICATION

Abstract

The article explores object-oriented programming (OOP) as a conceptual and practical mechanism for establishing a stable contract between backend systems and mobile applications in modern client–server architectures. In contemporary software development, mobile applications operate in close integration with server-side components through APIs, where inconsistencies in data models and interaction rules often lead to runtime errors, increased maintenance costs, and technical debt. The study emphasizes that OOP should be considered not only as an internal implementation paradigm, but also as a formal tool for defining inter-system agreements.

Special attention is given to the role of object-oriented data models, interfaces, and Data Transfer Objects (DTOs) in ensuring structural and behavioral consistency between backend and mobile clients. The principles of encapsulation, inheritance, and abstraction are analyzed in the context of API stability, reduction of coupling, and support for parallel development processes. The article examines typical architectural approaches based on OOP and highlights common integration issues caused by contract violations, such as unversioned model changes, type mismatches, and the use of weakly typed or dynamic data structures.

An experimental client–server system was designed to evaluate the impact of object-oriented contract violations on application stability. Several scenarios involving changes to backend models were analyzed, demonstrating a significant increase in critical failures when object-oriented contracts were not preserved. The results confirm that the use of DTOs and clearly defined interfaces substantially reduces integration errors and improves system reliability.

Based on the findings, the article provides practical recommendations for designing consistent interaction models between backend services and mobile applications using object-oriented principles. The proposed approach contributes to improved predictability, maintainability, and scalability of software systems and can be applied by mobile developers, backend engineers, and software architects working in Agile and DevOps environments.