Dear OGSA WG, In the object-oriented world, components such as Java Beans or ActiveX controls are typically defined by a set of properties, a set of methods and a set of events. In the service-oriented world we have a similar requirement, dealing with interoperable messages rather than a language API. What is the best way to specify the notifications that a service or interface can send? The OGSA document describes a virtualization as a "common set of abstract interfaces available for a set of similar resources, thereby hiding differences in their properties and operations". To this we somehow have to add the notifications that can be generated, as these are an essential part of virtualization. Are the notifications part of an interface? Are they actually specified in any of the metadata for a service? The OGSA document defines an interface as follows: "In a service-oriented architecture, a specification of the operations that a service offers its clients". Should this be extended to include properties and/or notifications? This is a live issue for the Data Architecture document. Best wishes, Dave Berry Research Manager, National e-Science Centre 15 South College St., Edinburgh Tel: +44 131 6514039