Alembic and Other Input Data Formats
It is possible to bring in 3D scene data from any source. However, due to the way that filters can get called recursively on-demand, it is best to work with formats that can be efficiently accessed in this manner. This is one of the reasons that we recommend Alembic as being ideally suited for delivering assets to Katana.
If you want to write a custom plug-in to read in data from a new source, such as using an in-house geometry caching format, you can write an Op Type plug-in. This is a C++ API that allows you to create new locations in the scene graph hierarchy and set attribute values at those locations.