I'm working on the Mini-language <set-current-user-login> element, and I
wanted some feedback about this TYPE of operation.
Background: There are some things in the Mini-language script execution
context that, from my perspective, should be read-only. Some of those
things are the delegator and security credentials (there are others -
see SimpleMethod.java, line 85). From a scripting standpoint, I believe
it helps the developer if those things are constant or immutable, and
provide a means to override them explicitly in certain circumstances. In
other words, the scripting language should be designed in a way that
facilitates writing good scripts.
Giving the developer the ability to override those things opens up the
potential for quirky and possibly unsafe code. Changing the delegator or
user credentials mid-script might seem convenient at first glance, but
it becomes a debugging and code maintenance nightmare later on. There is
a better way to handle the need to use different artifacts during script
execution. For example, instead of changing the script's delegator,
entity operations could support specifying the delegator to use. The
explicit use of an alternate delegator is easier to understand and debug
than a delegator change that occurred somewhere else in the script
execution path (a path that might include other simple methods).
The same thing could be done for security credentials. The Mini-language
schema says the <set-current-user-login> element "...is mostly used for
calling services, etc" - but you can provide an alternate UserLogin to
the service via the IN attributes. Therefore, that element is not necessary.
A lot of existing Mini-language code performs those mid-script artifact
changes, so this isn't something that can be changed overnight. What I
propose is a "best practice" where that type of operation is discouraged
in the Mini-language documentation. Maybe in a future version of the
grammar, elements of that type can be deprecated.
What do you think?
-Adrian
