Proxy Layer need for Micro Service Application

In Micro service Applications it is better to add a proxy layer above the service layer to handle lot of things like communication , security etc. but I searched for a details for that layer (in Java as example) to see the power of using this type of proxy layer and how to be implemented ? and I did not reach to suitable answer for this question .

So I need a detail illustration for this (I appreciate that); and also the recommended design patterns for building micro service applications .

Actually I don't know if my question is related directly to software architecture design or something else ; so I apologize if it is not related .