[jira] [Resolved] (ISIS-1291) Define new DTO (XSD) as the memento for Command#setMemento

["Dan Haywood (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ISIS-1291?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dan Haywood resolved ISIS-1291.
-------------------------------
    Resolution: Fixed

> Define new DTO (XSD) as the memento for Command#setMemento
> ----------------------------------------------------------
>
>                 Key: ISIS-1291
>                 URL: https://issues.apache.org/jira/browse/ISIS-1291
>             Project: Isis
>          Issue Type: New Feature
>          Components: Core
>    Affects Versions: 1.11.0
>            Reporter: Dan Haywood
>            Assignee: Dan Haywood
>            Priority: Minor
>              Labels: implemented
>             Fix For: 1.13.0
>
>
> A command is NOT an action invocation, it is an INTENTION to invoke an action.  Generally that intention is carried out immediately, hence a foreground command.  Sometimes though it is carried out in the background, so is a deferred intention.
> What this implies is that a command should not contain details of the action's results.  (If that information is available from reified ActionDomainEvents, then they can be contributed/mixed in)
> A command should cope with the concept of being invoked on more than one object, ie having a list of targets.  nb: this implies that our current terminology of "bulk actions" is actually wrong, we ought to be talking about "bulk commands".
> We can envisage (at least) two different user intentions when performing a bulk command:
> a) perform the operation on as many as possible, or
> b) perform the operation on all of them, or none at all.
> The former suggests that each action is wrapped in its own command: the user intends to operate on each object, one after the other.  The latter suggests that all the actions live in a single command.
> Dan's view is that a command is one:one with a (DB) transaction.
> ~~~
> the original version of this ticket was to change the Command#setMemento to use the ActionInvocationMementoDto.  However, that now seems to be incorrect:
> - an AimDto is a record of an action being invoked (past tense, if you will), not the intention to invoke an action
>   - as such an AimDto holds a return value, but that is strictly irrelevant to a Command
> - an AimDto relates only to a single target, whereas a Command could have multiple targets ("perform this action on all of em, or none of em")
> So, instead, this ticket is to define a new XSD just as the reified form of Commands.  It needs to be able to handle mxins, and bulk actions.  It *shouldn't* have action results.
> ~~~
> Note that this will also require some data migration scripts for anyone that has used this feature.



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