On 8/31/2012 4:20 AM, Alan Bateman wrote:
On 31/08/2012 08:59, Joe Wang wrote:
Yes, it works just fine under normal conditions.
Note the old process: read the service file using TCCL (if null,
system cl), if nothing found, then BCL
Somehow I was under the impression ServiceLoader does just that so
that we could delegate to it. It's probably a good thing that it
actually doesn't. If it did, it'd cause error in the following case:
The TCCL's parent is BCL (that is Bootstrap), a jaxp impl (e.g.
Xerces) is on the classpath
Old process: try TCCL, not found, try BCL, not found
ServiceLoader: use TCCL, not found, return null (I thought it'd
continue using System CL, but it didn't)
**although worked differently, the results are the same, so not
an issue in terms of the result, still a behavior change though.
I did many tests, but so far the results are the same before and
after the patch.
If TCCL is set to null, I actually saw SCE other than SchemaFactory,
for example:
javax.xml.stream.FactoryConfigurationError:
javax.xml.stream.XMLEventFactory: Provider
org.apache.xerces.stax.XMLEventFactoryImpl not found
--Joe
This is a mess. I realize it pre-dates your watch but it looks like
we're going to have to sort this out in order to make progress. I
think sorting this out will require some behavior changes so that the
factories are located in a consistent manner and also work
consistently when there is a security manager set.
So what would you think about putting the ServiceLoader changes on
hold for a little bit and spending some time to get the factory
finders working consistently. I hope this will be mostly just fixing
the SecuritySupport.getContextClassLoader implementations and so will
not conflict with the SL work. As part of this then we get a list of
existing vs. proposal behavior for each factory and for each of the
security manager + no security manager cases. This will allow us to
assess the impact to each factory finder. My gut feel is that the
impact will not be too significant and in most cases will be an
improvement to how it works today.
I also agree with Paul about getting a useful set of tests as it's
impossible to say from reading the javadoc how it should behave. These
tests will help you to get the list of current behavior, proposed
behavior and should give you confidence when you get to the changing
this code to use ServiceLoader.
Okay, let's streamline the factories. I think we should:
1) align to the SAX/DOM since these are most frequently used, and
proven. Any changes to other factories will have lower impact in
comparison;
2) no spec change involved: for example, the StAX factories have
newFactory/newInstance(String factoryId, ClassLoader classLoader), while
others define the first parameter as factory classname, e.g.
newInstance(String factoryClassName, ClassLoader classLoader). We also
know that some factories have throws clause while others don't. In this
effort of making factories behave consistently, we'll restrain from
making any spec change.
--Joe
-Alan
