Attribute-Based Programming for Grid Services

One of the key challenges for a “Grid programmer” today is how to expose functionality as an OGSIcompliant Grid Service. One of the principle differences between programming a Grid Service and simply coding the service logic is that a certain amount of meta-data is needed to actually expose that service logic as a grid service. This meta-data consists of instructions to the service’s hosting environment about what elements (methods and data) should be exposed to clients and the conditions under which clients can access them (policy). This goes beyond simple automatic generation of service WSDL and client-side proxies to describing events that must be analyzed at runtime. In this paper, we describe the attributebased programming model that we are developing as part of OGSI.NET, an OGSI-compliant hosting environment for the Microsoft .NET platform. Programmers annotate their code with attributes that are subsequently used by both pre-processing tools (e.g., to generate static information such as WSDL documents) and by the service’s hosting environment (e.g,. to detect policy events). We focus on Service Data Elements (SDEs) and Service Security Policies. We argue that an attribute-based model can ultimately make creating a Grid Service as easy as creating a Web Service.