Calling DoS Developers or System Administrators

As a Java developer, I am going to participate in a web project. Therefore, I am trying to get information about various aspects of Internet security.

Now I come to the topic of DoS attacks, and I'm trying to understand what I can / should do as a Java developer. Perhaps this will be the work of the system administrator.

At first it comes to my mind to implement functionality in such a way that one request cannot take up too much time and resources. For example, to limit the amount of data processed. But I'm not sure if this applies in all cases.

Do I have to take care of DoS due to many requests?

Any advice would be appreciated. Thank you very much in advance!