createSnapshot Step

A step used to create a snapshot of the current installed state of the component being installed. Any number of <createSnapshot> steps may appear within an install block.

The named snapshot block may not declare any required parameters, as the createSnapshot step does not support argument passing. Argument passing is not supported because doing so would also require support for argument collection and passing at the time a comparison is later performed on the resulting snapshot.

When a comparison is performed on a composite component, it includes all snapshots created directly by that component, as well as the complete tree of snapshots created by the recursive installation of all nested component references. However, snapshots associated with toplevel component references are not considered, and therefore must be explicitly included in the snapshot of the composite component using the <addSnapshot> capture directive, as appropriate.

Also note that nested components may have some inter-dependencies that make it necessary to defer snapshot capture until all such components are installed. A nested component that deploys a directory and a nested component that deploys a file into that directory is an example of such an inter-dependence. In these cases, it is recommended that the containing component install the nested components using parameter passing or special install blocks that tell the nested component not to take the snapshot during their install, and then have the snapshot block of the containing component include appropriate snapshots of the nested components using the <addSnapshot> directive.