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In this talk we will consider a special subclass of the Hardy-Hilbert space $H^2$ namely de Branges-Rovnyak spaces $H(b)$, first with an introduction of model spaces in the unit disc and then in the setting of the unit ball of $\mathbb C^n$. One of the main problems in the study of $H(b)$ functions is their integral representation and in this talk we will see how we can represent these classes through the Clark measure on $S^n$ associated with $b$. In the second part we will give a characterization of admissible boundary limits in relation with finite angular derivatives and we will see the interplay between Clark measures and angular derivatives showing that Clark measure associated with $b$ has an atom at a boundary point if and only if $b$ has finite angular derivative at the same point. More detailed analysis of the concepts mentioned in this talk can be found in the following study.

[1] Şahin, S., Angular Derivatives and Boundary Values of $H(b)$ Spaces of Unit Ball of $\mathbb C^n$, Complex Variables and Elliptic Equations, Volume 66, Issue 2, pp:226-237, (2021).