Techniques are described for service mapping and other backend operations for a collaborative platform. A platform may access data objects from any suitable number of source services. The data model of the platform may be dependent on the data models of its associated source services as well as source service annotations, where such annotations describe the mapping onto the various data model elements. The process of mapping requests and results between the platform and the external data sources at runtime may employ a schema mapping data structure to minimize potential performance impacts. Implementations may employ a hierarchical class structure that is configured to achieve efficient traversal by shifting computational load to initialization time when the source service data models and annotations are processed. The initialization of the structure may be triggered at initialization time of the platform or whenever an administrative action causes changes to the schema mapping.