Antoine Bordes provides an implementation of the OLaRank algorithm.

OLaRank is an online solver of the dual formulation of support vector machines for structured output spaces. The algorithm can use exact or greedy inference. Its running time scales linearly with the data size, competitive with a perceptron based on the same inference procedure. Its accuracy however is much better as it replicates the accuracy of a structured SVM. See the ECML/PKDD paper "Sequence Labelling SVMs Trained in One Pass" for details.