One of the main steps of service assurance is service monitoring using Key Performance Indicators (KPIs) and Service Level Agreements (SLAs). We show an approach for service modeling, first starting with an abstract service model that depends on the network. And then, we show how a corresponding model can be realized using a domain specific language. This solution is able to condense various sources of service model requirements into a condense formal and executable model including service decomposition and KPI aggregation. We have described this solution in the context of Magneto project and uses IPTV as a service in our description.