[jboss-as7-dev] Management proposal for attribute mutability

Currently we have way too many read only attributes in our management model. This makes life harder for the management tools and/or makes the resulting UI a bit unwieldy. In some cases this is just because we haven't polished subsystem management (PLEASE all subsystem authors look at this!). In other cases though it's intentional because it is either difficult or currently impossible to make hot changes to a particular attribute. This should be exceedingly rare. Users love hot updates, and it's a competitive advantage. So first we should strive to make it hot in the first place. However in the case that the change is not hot, and a server reboot is too aggressive, we should still supporting making the changes by bouncing all services involved. After some debate on IRC we finally arrived at what is IMO a really good option for this problem: write-attribute (impact-services=true|false) The operation handler on such a non-hot attribute would then return an error if false (the default), but would continue and bounce everything needed if the value is true. In addition we would add some simple description metadata that would allow tools to handle it right away instead of reacting to the error response. For a practical example look at datasources. Due to limitations in JCA we have to restart the resource adapter if the jdbc connection url changes. While it should be possible to one day make this change hot, we can for the time being still allow the user to type in a value. They would however be prompted with some kind of dialogue that would confirm the impact of this change. -- Jason T. Greene JBoss, a division of Red Hat