Development of server and client part

Web developer services are required. It requires the development of the backend and the Java client.
Required work experience: 3-6 years
Project/Temporary work
Responsibilities:
Participation in the development of the backend and client part of the distributed application on the Java platform using the Vaadin Framework;
Development of information system components according to specified specifications;
Debugging, writing modular and integration tests;
Elimination of errors;
Preparation of documentation.

Requirements:
Experience in server application development (Java EE, Spring, web-services & etc.) in the case of Back-End developer
Knowledge of Vaadin, CSS is welcome.
Excellent command of Java
Understanding data structures, OOP fundamentals and design patterns, understanding UML
Experience with Apache Commons, Spring Framework &, etc.
Experience with databases (PostgreSQL/Oracle), knowledge of SQL
Experience with application servers/web servers (Apache Tomcat & etc.)
Ability to work with automation tools for assembling projects (Maven, Gradle & etc.)
Ability to work with version control systems Git, Cvs
Ability and desire to deal with the source code already existing in the project;

Conditions:
Income level discussed in the interview