a grid management service for deploying legacy code applications on the grid , without modification of the legacy code , the service having a three layer architecture that is adapted to sit on existing standardised grid architectures , comprising a front end layer for permitting selection of a desired legacy code application , and for creating a legacy code instance in response to the selection ; a resource layer , for defining a legacy code job environment ; and a back end layer , for submitting a job for said desired legacy code application , together with information relating to said job environment , for submission to a job manager that arranges for said job to be executed on grid resources .