For a pseudodifferential boundary operator A of order v epsilon Z and class
0 (in the Boutet do Monvel calculus) on a compact n-dimensional manifold w
ith boundary, we consider the function Tr(AB(-s)), where B is an auxiliary
system formed of the Dirichlet realization of a second order strongly ellip
tic differential operator and an elliptic operator on the boundary. We prov
e that Tr(AB(-s)) has a meromorphic extension to C with poles at the half-i
ntegers s = (n + v - j)/2, j epsilon N (possibly double for s < 0), and we
prove that its residue at 0 equals the noncommutative residue of A, as defi
ned by Fedosov, Golse, Leichtnam and Schrohe by a different method. To achi
eve this, we establish a full asymptotic expansion of Tr (A(B - <lambda>)(-
k)) in powers lambda (-1/2) and log-powers lambda (-1/2) log lambda where t
he noncommutative residue equals the coefficient of the highest order log-p
ower. There is a related expansion of Tr(Ae(-tB)).