Issue #6021 - PoC for resolvePath within XmlConfiguration

[joakime]

This is a proposal / draft PR for simplifying the whole management of paths within our XmlConfiguration.

Signed-off-by: Joakim Erdfelt joakim.erdfelt@gmail.com

[joakime]

This could easily be done with a new element, but after discussion with @sbordet i felt doing via a static method was the minimal to prove the concept out.

This draft PoC looks like ...

<Set name="keystorePath">
  <Call name="resolvePath" class="org.eclipse.jetty.xml.XmlConfiguration">
    <Arg><Property name="jetty.base"/></Arg>
    <Arg><Property name="jetty.sslContext.keyStorePath" default="etc/keystore.p12"/></Arg>
  </Call>
</Set>

The XML element version could look like ...

<Set name="keystorePath">
  <Path base="${jetty.base}"><Property name="jetty.sslContext.keyStorePath" default="etc/keystore.p12"/></Path>
</Set>

Where the attribute base is optional and defaults to jetty.base internally (Note that jetty.base is always guaranteed to be defined when using the XmlConfiguration anyway)

[joakime]

We could have used the Paths.get(jetty.base).resolve(dest).toString() in the XML language, but there is a need to have a Path that can be unset/empty/null in configuration, which our current XML doesn't support really well, and the direct usage of Path.resolve doesn't address either.

[joakime]

This proposal works for absolute paths, relative paths, linux, windows, OSX, machine shares (aka \\machine\share\path), etc.
Pretty much anything that can be represented by a Java Path object and is supported by Java's FileSystem implementation.