While working and testing direct and redirecting command handlers for BSF4ooRexx I developed an
external function named BsfCommandHandler() with the following invocation possibilities for the
ooRexx side:
* BsfCommandHandler "add", "environmentName", jhandler
adds a command handler for "environmentName" and a Java/NetRexx implemented
Rexx direct or
redirecting command jhandler
* BsfCommandHandler('list')
returns an array of currently known Java/NetRexx jhandler, indicating for
each jhandler whether
it can be used for redirection or not
The "add" version uses the AddCommandEnvironment()-API.
The "list" version is only able to supply the Java-side known handlers (either from the Rexx
instance configuration or/and from using the BsfCommandHandler-"add" subfunction).
However, currently it is not possible to list those command handlers that are not implemented in
Java and added through BSF4ooRexx, but by others using AddCommandEnvironment() directly. So, if
native command handlers get added with AddCommandEnvironment() and denote e.g. an existing
environment name serviced by a Java handler, the native one will replace the Java handler. Yet, the
BsfCommandHandler-"list"-subfunction will currently still return the list of known Java handlers,
not being able to realize that one of the Java handlers got replaced by a native one. The reason is
that there is no API currently available that would return the necessary information.
Therefore suggesting an additional command handler related API that would return the current list of
Rexx command handlers in a way that allows native programmers to learn whether the handlers are
known to them or from others. This could be achieved e.g. by returning a two or three dimensional
RexxArrayObject with index=1 "environmentName", index=2 RexxPointerObjectForHandler [, index=3
isRedirectingHandler].
Having a RexxPointerObject (for the respective handler) one can identify on the native side whether
the handler is from one own's package or not, thereby updating/correcting the package known list of
registered command handlers. Using a three dimensional array as return value would allow for
indicating whether the command handler is direct or redirectable, which would allow for
incorporating this information e.g. in the BsfCommandHandler-"list" (and also removing the replaced
Java handler in such a case).
Maybe the name for such an API could be something like
"GetAllCommandHandlers()".
Without such an API one is not able to return a list of *all* currently defined command handlers
correctly and determine whether one own's handlers got replaced by others during the program's life
time (becoming able to remove Java handlers in such a case, thinking of 7/24 deployments).
Would that be a sensible addition?
---rony
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