Hi,
An easy way to make ServiceLoader loaded services decide at runtime for
themselves if they want to be enabled or disabled is a little addition
to their behavior. Suppose that a new exception type is defined:
IgnoreServiceException. When this exception is thrown from the
constructor of the service implementation, ServiceLoader could just
ignore such service and behave as though it wasn't provided.
Would that work?
Regards, Peter
On 03/28/2016 01:42 PM, David M. Lloyd wrote:
The reason is because we use a single boot path but we don't know at
the time of boot whether or not we will have a JAXP provider, nor
where it will come from; that is up to the server configuration that
we end up running. With the system properties approach we can just
clear all the properties, but if we use ServiceLoader then we can't
switch it on and off on demand.
On 03/26/2016 04:57 PM, huizhe wang wrote:
Going back to the original issue a bit, if you don't mind.
The issue was that JBoss wished to configure its own default providers
for certain JAXP-defined services. What you've been doing until now was
to point the system property to a proxy, which, in essence, took over
the JAXP provider-lookup process, and served as a factory finder outside
of JAXP. "however if we do this but there is/are no overriding
implementation(s) for one or more of these APIs, then AFAICT it will
fail with Jigsaw because we can't access the JDK's default
implementations".
So the question is, why did you have to override the JAXP process for
the services that you don't have an AppServer-level provider (
"overriding implementation(s)" )?
Thanks,
Joe
On 3/25/2016 5:53 AM, David M. Lloyd wrote:
OK, so disappointment again. :) Thanks for responding; the search
continues.
On 03/24/2016 06:35 PM, huizhe wang wrote:
Right, that sounds like what I thought you would want: an additional
step in the factory-lookup process to try locating a provider through
the Layer of the caller if TCCL fails. I think the assumption in the
previous discussion was that a new method would be introduced to
take a
Layer as an argument.
-Joe
On 3/24/2016 3:36 PM, David M. Lloyd wrote:
This is all for the case where the user is calling e.g.
javax.xml.stream.XMLInputFactory#newFactory() with no arguments. We
need some way to choose a specific non-JDK default implementation
when
there is no service loader info on the TCCL. Using the Layer of the
caller of the newFactory() method would be an ideal solution from our
perspective.
On 03/24/2016 05:18 PM, huizhe wang wrote:
So specifying Layer is preferred solution. If a new method is needed
however, (similar situation to using the method with ClassLoader),
that
would mean your users' applications are required to adapt to the new
API. Would you expect that would happen or would you still have
existing
applications that can not be updated?
-Joe
On 3/24/2016 2:02 PM, David M. Lloyd wrote:
On 03/24/2016 03:54 PM, huizhe wang wrote:
In this discussion so far,
a) I see that you seemed to have successfully used the method
with a
class loader as Daniel suggested. I assume that solved the issue
reported in JDK-8152063. Am I right, that you no longer have issue
with
using a proxy? Or
No, not solved yet, just in the process of prototyping but ran
into a
road block with XMLReaderFactory.
b) you do need JAXP's supporting using a Layer as the context in
order
to solve your issue completely?
I think this should be considered the best solution to the problem.
c) On org.xml.sax.helpers.XMLReaderFactory, as Alan and Daniel
said, yes
I'm working with the SAX project to hopefully get a new release
out
that
would conform to the ServiceLoader spec. I'm also suggesting a
new
method that takes a ClassLoader that would be useful if (a) worked
for you.
We have some more testing to do before I can say whether this
works or
does not work. But either way it is a rather non-optimal solution,
and if I can avoid using a proxy layer, I would much prefer to
do so.
Thanks for your response.
