Add option to append the file name to the md5/sha1 checksums

Can all versions of Maven consume a checksum with the filename appended? If so, should we just make this the default? (is there a standard checksum file format?)

Ant's checksum task has the facility to supply a pattern for the checksum output:
http://ant.apache.org/manual/CoreTasks/checksum.html

This provides more flexibility - I can provide a patch for that if required.

Docs on the checksum file format are hard to find - wikipedia has the following which mentions this format:
http://en.wikipedia.org/wiki/Md5sum

Attaching an alternative patch that provides the option to specify a MessagFormat style patterns for the MD5 and SHA1 checksums:

Has two new pattern properties (md5Pattern and sha1Pattern) where {0} is replaced with the checksum, {1} with the file name and {2} is a new line.

This is almost the same as the functionality provided by the Ant checksum task and gives greater and individual control over what is output for both md5 and sha1 checksums.

Niall, what do these checksums get used for? I'm not opposed to the patch, just curious.

The feature to create checksums was added in MINSTALL-9, so we might as well give the user control over what the checksums look like.

As far as I can tell, Maven ignores checksums for files that are already in the local repo. (So my question about whether Maven can consume this new format is irrelevant for the install plugin.)

Can all versions of Maven consume a checksum with the filename appended?

As per MNG-797, many versions can handle the format requested by Niall. Only SHA-1 checksums in OpenSSL format were not handled (MNG-1349).

What might need further investigation is how we deal with local vs. remote checksums. Niall's patches are straightforward but their effect would be limited to the local repo. The checksums deployed to remote repos are created by the Maven core, i.e. are independent from the checksums created by the Install Plugin. Unless we sync the formats between core and Install Plugin, the format of a checksum file depends on whether it was locally installed or downloaded remotely. Not sure how useful that is.

When we wanted to sync the formats, we would need a way to configure the format used by the Maven core. Not sure how to do that without expanding the POM structure, i.e. have some new elements within <distributiionManagement>.

To avoid the configuration issue and have equal local and remote checksums, I suggest we start off by hard-coding the format suggested by Niall in his first patch, both for the Install Plugin and the Maven core:

<checksum><space>*<filename><newline>

Corresponding discussion thread on dev@: Checksum Format for .md5 and .sha1 Files.