There are many legacy code applications that cannot be
run in Grid environment without significant modifications.
To avoid re-engineering of legacy code, we developed the
Grid Execution Management for Legacy Code Architecture
(GEMLCA) that enables deployment of legacy code
applications as Grid services. GEMLCA is an OGSI Grid
service layer that supports submitting jobs, getting their
results and status back. Security requirements are essential
to any Grid application to preserve the confidentiality and
integrity of data. To meet these requirements the GT3
security model was implemented in GEMLCA. The paper
introduces GEMLCA and how Grid Security Infrastructure
(GSI) components have been added to GEMLCA in order
to enable secure execution of jobs in Grid. The paper also
presents how a legacy code traffic simulator was transformed into a Grid service using GEMLCA and gives some simulation results.