Java project with spring framework

Task System v.1.2 Your job is to build a highly scalable processing backend that handles “tasks". Each task could be between 1-20 seconds long and each produce a result that the client of the backend wants. The solution should be a backend using a Restful API for the job, preferably using either a polling or a notification/callback scheme to get the result. Design it in a suitable way for a very intensive environment that may have over 400+ calls per second. Think how the application would scale with such load. You may, - use a message queue and/or broker, and you should use a restful web-framework. - have multiple applications, and multiple instances of each application. You should provide, - small information overview of the chosen architecture - provide which frameworks/libraries you would use - prefer actual code or code fragments, of each important piece. (pseudo code may be used as well) - small documentation for each API method that you make available. - discussion/reflection of potential issues that may arise when using this system that you intend to build. Scalability is important. Notes: - The solution / application does not have to be runnable, but it should be obvious that you can build/create it, given the information you provide as the solution. - Solution should be based on Java and Spring ecosystems.