Grid computing enables the sharing of heterogeneous resources among different administrative domains promising unlimited computational and storage power available on demand. However, Grid applications are often developed in an ad-hoc manner with little or no transferability across them. Grid applications not only need to adapt to evolving standards but they also need to adjust to a dynamic environment in which resources can be added and removed on demand. This book presents an approach that simplifies the development of Grid applications and empowers end-users to take full advantage of Grid infrastructure. The approach uses domain specific modeling, a modern software engineering method for automating the development of software, to develop a workflow tool that can be used by end-users to create complex Grid applications graphically. This book provides an introduction to Grid computing and workflow systems as well as a practical exercise in domain specific modeling. As such, this book should be of great use for software engineers and anyone else interested in reaping the benefits of Grid computing and scientific workflows.