A crucial aspect of the architecture of a software system is its decomposition into components and the specification of component interactions. In this report we use a variant of Extended Event Traces as a graphical technique for the description of such component interactions. It allows us to define interaction patterns that occur frequently within an architecture, in the form of diagrams. The diagrams may be instantiated in various contexts, thus allowing reuse of interaction patterns. Our notation contains operators yielding not only exemplary but complete behavior specifications. Extended Event Traces have a clear semantics that is based on sets of traces. We present several application examples that demonstrate the practical use of our notation.