Service-oriented architectures are increasingly used in the context of
business processes. However, the proven practices for process-oriented
integration of services are not well documented yet. In addition,
modeling approaches for the integration of processes and services are
neither mature nor do they exactly reflect the proven practices. We propose a pattern language for process-oriented integration of services to describe the proven practices. We also propose a modeling concept based on pattern primitives for
these patterns.  A pattern primitive is a fundamental, precisely specified
modeling element that represents a pattern. We present a catalog of
pattern primitives that are precisely modeled using OCL constraints and
map these primitives to the patterns in the pattern language of
process-oriented integration of services.