The transformation of interacting fermions into free bosons known e.g. from the solution of the Luttinger model is reconsidered in a condensed version which combines all fermionic degrees of freedom in a single boson field. This simplifies calculations as compared to the usual separate treatment of the charge degrees of freedom. The representation of the fermions is exact. The Thirring-Schwinger model is described and solved with special emphasis on boundary effects. Implications for massive fermions are briefly mentioned.