The Grid Application Toolkit (GAT) provides a layer between applications and grid infrastructure which provides abstract grid functionality through application oriented APIs. These high level APIs also insulate applications against the current rapid evolution of grid infrastructure and the state of grid deployment. The API functionality is provided by plug-ins which can utilize any mechanism to provide the desired functionality. For instance in the GridLab project the functionality is provided by Globus-based grid services (OGSA). A GAT is not restricted to using GridLab services, however, and thus an alternative GAT using other services, e.g. using 3rd party services, using Globus services directly, or using non-Globus based services, can be built. The GAT is designed to be able to incorporate new technologies, to allow service discovery and dynamically swappable services, to allow strict security policies to be implemented, and to provide the application with necessary control and information.

Core user and developer tools, such as the GridLab GAT and Portal are essential for bringing application communities to the Grid. At the simplest level, they will provide a migration path for current applications to make use of Grid capabilities: resource brokering, job staging and tracking and data locations and archiving. More exciting though are the possibilities they create for constructing whole new classes of intelligent environment-aware applications and collaborative working practices when robust, fault tolerant application-level services such as event notification, migration, spawning and resource brokering will be intuitively available through simple APIs and portal interfaces to programmers and end users.

We will give a brief introduction on the Portlet API and its implementation in GridSphere. In addition, we will demonstrate its use with the GridLab Portal and demonstrate several portlets which will enable us to serve broader communities of users, such as our messaging and notification portlets that enable users to receive notifications about the status of their Grid applications via Email or SMS.