Jun, It is unclear to me what a simple use case for this would look like. These seem to be conflicting requirements, not a single complementary one. You could define the CDL language to allow a default value for a lazy parameter, thus eliminating the lazy resolution. I think that it is dangerous to modify the component model to define how it interprets CDL. The CDL language should be defined clearly and separately from the component model. To date, the component model has only define normative schema elements to be used as valid CDL. Stuart -----Original Message----- From: owner-cddlm-wg@ggf.org [mailto:owner-cddlm-wg@ggf.org] On Behalf Of Jun Tatemura Sent: Tuesday, April 18, 2006 5:58 PM To: 'cddlm-wg@ggf.org' Subject: [cddlm] issue on a component property value Dear team, In the F2F discussion with OGSA team, we had a question on our specs. We promised that we will discuss in the WG. [Q] Can a component have a parameter such that (1) sometimes the user want to specify a value but (2) sometimes the user want the component to specify the value dynamically (as a default value). In fact, it is not obvious from the current component model or CDL. A default value of a component property can be introduced, for example, as param2 in the following component description, Component1. If the user extends this template without specifying a value on param2, 100 is used as a default value. However, how can a dynamic value be default? <Component1> <cmp:CommandPath .../> <cmp:CodeBase .../> <param1 cdl:lazy="true"/> <param2>100</param2> <Component1> For a dynamic value, we use @cdl:lazy. When param1 is assigned by the component, we should specify @cdl:lazy so that any reference to this property is resolved at run time. However, specifying @cdl:lazy at a property does not mean that the component MUST/SHOULD assign a value to the property. It does not mean that the user MUST NOT/SHOULD NOT assign a value either. In fact, CDL does not have any notion on a role who assigns values (such as users, systems, components, etc). For CDL, it is fine if the user assign the value to a property with @cdl:lazy. CDL only cares when a reference to the property is resolved. In this sense, the question to the answer can be 'yes' - the user can assign the value to the above param1. But we do not know whether the value is used by the component (or just ignored). In CDL, we cannot say if a component allows the user to specify a specific property. In fact, in the early design discussion, we were discussing @cdl:use="readonly" for that purpose: <param1 cdl:lazy="true" cdl:use="readonly" /> For some reason (I don't remember), we have removed this from the spec. This means that (1) any reference to this property is resolved at run time (2) you cannot override this property by inheritance -- in a component model, this means that the value can be assigned only by the component (the user is not allowed to assign the value) A possible solution would be one of the following: [1] CDL-level solution: add "readonly" as a value of @cdl:use [2] Component-level solution: extend the component model specification so that one can specify how a property is used by a component. [3] Application-level solution: just let it unspecified (as is) and think this as a semantic level matter the component model does not care.