To get rid of Seam (bug 1094534) we need to get rid of Seam Text. Seam Text and the RichFaces editor for it have been a source of bugs, plus it is not a standard format users are familiar with.
We plan to replace our current support for editing and rendering Seam Text with support for CommonMark (standardised MarkDown).
Automatically migrating the existing Seam Text to CommonMark is out of scope due to complexity (eg see bug 1065234), but we will track whether each piece of text has been saved since CommonMark support was added. This will let us notify the user, and could potentially be used to enable an automatic migration in future, should someone implement it.
See also the following Seam Text bugs, which should be eliminated by this feature:
* bug 1065234
* bug 1056296
* bug 1056301
Pull request: https://github.com/zanata/zanata-server/pull/732
A note on the testing and on the conversion approach:
I have a test (not checked in) which I used to run the conversion method against every bit of Seam Text I could find in all the production databases I could find, comparing the original rendered Seam Text and the rendered CommonMark. I fixed some bugs in my conversion, massaged some of the data (in production) and told it to skip over some others which looked like plain old HTML (not Seam Text).
I have also run Zanata server (and thus the Liquibase migration) against copies of all the production databases. As expected from the previous test, there were a number of warnings for invalid Seam Text, all of which probably cause rendering failures in production, like bug 1065234.
In the cases I looked at, the result looks better now that it is rendered as CommonMark/HTML, since most of these cases were actually HTML. There was one case which was mostly rendered as HTML source in monospace, but it previously didn't render at all, so I still consider it an improvement.
Note that some valid Seam Text (ie with Seam Text markup inside HTML tags like <p>) may be transliterated to similar CommonMark, but because CommonMark doesn't process CommonMark inside HTML tags, it will be rendered a little differently.
A common case is underscores in URLs inside HTML, which were always badly handled in Seam Text, especially if there was an odd number of underscores. In cases like this, the converted keeps the underscores as underscores, rather than converting to <u></u>. This will probably fix a few URLs which were broken by Seam!
A slightly worse case is emphasised text (using * markup or similar) inside HTML, which will be replaced by the CommonMark equivalent markup, but rendered as ASCII (and still quite readable) unless someone removes the surrounding HTML in the editor.
VERIFIED with Zanata 3.7.0-SNAPSHOT (git-jenkins-zanata-server-github-pull-requests-3566)
FYI: Upgrade commonmark.js to 0.19.0