the speed can be very well worth it. your concerns are valid enough and the
ejb1.1 spec is clear enough on the topic by requiring that RMI by-value
semantics are to be followed by a compliant server. the vendor in question
has announced that they are enhancing their implementation to follow
by-value semantics by default while allowing current customers like myself
to use by-ref if they choose to.
> -----Original Message-----
> From: Chip Wilson [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, June 10, 1999 10:24 AM
> To: [EMAIL PROTECTED]
> Subject: Intra-vm pass-by-reference optimization (again)
>
> Hello all,
>
> I am deploying an EJB application in multiple application servers. For
> the
> most part, portability has been very good to excellent, compared to the
> alternative technologies. I have encountered one huge problem, however.
>
> One of the app servers performs an "optimization" that breaks the
> application in many different ways. This server optimizes intra-vm bean
> invocations by changing the semantics of the bean method from
> pass-by-value
> to pass-by-reference. This quite predictably causes all kinds of problems
> as parts of the application that were never intended to share state end up
> walking all over each other's objects.
>
> I know that this is implicitly prohibited by the 1.0 spec, and explicitly
> prohibited in the 1.1 spec. I know that the argument has been made here
> and
> elsewhere that the performance improvement is "worth it".
>
> I also know that to an application developer, whether a method has
> pass-by-value semantics or pass-by-reference semantics is very important.
> So important that other languages (besides Java) which support both sets
> of
> semantics require the method declaration to indicate for each parameter
> and
> the return value which semantics apply. Saying that a particular method
> sometimes has one set of semantics and sometimes the other, and there is
> no
> way for the calling code to know which semantics apply on a given
> invocation, causes predictable guffaws from the rank and file.
>
> My questions:
> * How wide-spread is this "optimization"?
> * Do vendors have plans to deprecate this practice, or will it be
> carried forward?
> * Will there be a certification program to determine and publicize
> which servers are actually spec compliant?
>
> Chip Wilson
> ObjectSpace
>
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