I like this approach, I'm glad we're adopting it.
Lloyd
On Sep 21, 2009, at 5:03 PM, Bill Shannon wrote:
> We discussed this in our asarch meeting today.
>
> No one wanted to risk increases to the asadmin startup time by using
> OSGi. We're already trying to squeeze out fractions of a second from
> the startup time.
>
> Jerome pointed out that #4 isn't going to work because the command
> implementations in the extension class loader won't have access to
> the other asadmin classes in the application class loader. Thus,
> we decided that we needed to pursue option #2.
>
> Jerome thinks there may be some HK2 classes to help with constructing
> the URLClassLoader we'll need to implement #2.
>
> This approach will allow asadmin extension jar files to be installed
> into lib/asadmin and discovered by HK2 in asadmin.
>
> Let me know if anyone sees any issues with this.
>
>
> Bill Shannon wrote on 09/17/09 14:10:
>> I changed asadmin recently to use HK2 to allow the set of local
>> commands
>> to be extensible. That solved only part of the problem. Since
>> asadmin
>> doesn't use OSGi, there's no convenient, automatic way to install a
>> new
>> jar file that includes support for a new local command and have it be
>> seen by asadmin. Essentially there needs to be a way to add a new
>> jar
>> file to asadmin's CLASSPATH.
>> Here's the ways I've thought of to solve this problem:
>> 1. Use OSGi. I think this is excessive but I list it for
>> completeness.
>> 2. Have the asadmin code explicitly create a ClassLoader to load
>> classes
>> from some specific directory where asadmin extension commands can
>> be dropped.
>> 3. Have the asadmin shell script add all jar files in a specific
>> directory
>> to the CLASSPATH before running the java command.
>> 4. Have the asadmin shell script invoke the java command with the
>> System
>> property java.ext.dirs pointing to a specific directory where
>> command
>> extensions can be dropped.
>> Preferences? Other alternatives?
>> I'm assuming HK2 will work fine with any of the above.
>> Right now I prefer #4, with a directory something like "lib/asadmin".
>
Lloyd Chambers
lloyd.chambers_at_sun.com
GlassFish Team