Version 3.0 of the Domino Open Liberty Runtime
Dec 2, 2021, 4:46 PM
When I last talked about my Domino Open Liberty Runtime project, I mentioned the various main tasks I'd been doing in gearing up for a 3.0 release.
Well, it's been a while since then, but so it goes with open-source projects sometimes. Fortunately, I've had some time here and there to dust it off some more and take care of a lot of lingering tasks I had assigned to the 3.0 release, enough to make it to the finish line. Some of these I found interesting to note, and so I'll note them here.
Java Runtime Shifts
One of the neat tricks the project does is to auto-download a specified Java runtime for you: you can pick your version (e.g. 8, 11, or 17) and your flavor (HotSpot, OpenJ9, or GraalVM CD) and the tooling will do the work of downloading it on your behalf.
Originally, this used just AdoptOpenJDK, the previous go-to home of open-source Java builds. When I added GraalVM, I generalized the code to handle those downloads as well. Like AdoptOpenJDK's binaries, they're hosted on GitHub, but under a different organization and using a different naming scheme.
That refactoring paid off now: AdoptOpenJDK moved to the Eclipse Foundation and became the Adoptium project: much the same idea, but a new home. During that move, though, IBM stopped pushing OpenJ9 builds to that organization and instead now host them themselves, under the name Semeru. I assume this was all due to some wrangling over the use of "JDK" and other political scuffling, but either way I had to deal with it.
Fortunately, though the Semeru home page is standard IBM fare, the binaries themselves are still hosted on GitHub, and the organization still mirrors the original AdoptOpenJDK/Adoptium style. So I made another class for that, but the logic is largely the same.
Notes API Feature
Since it's extremely likely that apps deployed adjacent to Domino this way will want to access Domino data, I originally set up deployment to copy the server's Notes.jar into the global "extra JARs" directory for deployed Liberty instances. This would allow apps to make use of
lotus.domino classes without having to package Notes.jar inside the WAR.
This works well enough, but it always felt a little wrong: I don't like polluting the server's classpath that way, and it got all the worse because I needed to also bring in an open-source copy of CORBA classes for cases where the JVM in use is newer than 8.
So I decided to take another swing at it, this time packaging it up as a feature to be loaded as desired in Liberty. The project already has a few of these, generally consisting of the Liberty-specific OSGi bundle, the ESA feature file to define it in Liberty, and then an extension on Domino to deploy that to new servers.
In this case, I'd want to do it a little differently: the other ones included custom code on my part, but this one will just want to grab JARs from the Domino installation and make them available to apps. So, for this one, I didn't need the first two components - instead, I'd build the feature JARs on the fly. I went about doing that, the the result is a class that creates a
notesApi-1.0 feature automatically. It makes use of the way streams work in Java to automatically build a feature container based on the current Domino build version (in case the API changes), creating the necessary manifests programmatically and then locating Notes.jar, the NAPI, and their CORBA and IBM Commons dependencies.
This new route is nicer all around: it's explicitly opt-in, which I like, it now also provides the NAPI, and it hides the non-API dependencies from the apps.
For a while now, I've been toying with the idea of making this less Open-Liberty-specific and adding the ability to deploy different kinds of apps. After all, all Liberty is here is a forked process, and that could be anything: a different app server, a single JAR file, or something not Java-related at all. Though the tooling will still only support Open Liberty in 3.0, I've been gradually reorganizing the structure to make such a change practical to implement in, say, 4.0.
Rather than the core runtime assuming it's using Liberty, now it uses generic interfaces to represent any kind of server, and then that further drills down into servers that use a JVM, and from there down to a Liberty server.
This sort of genericizing has made the runtime much more service-based internally - it's more indirect and it takes more discipline, but I feel good about it. I picture it now as a central core coordinator (still named
OpenLibertyRuntime internally) receiving notifications of changes in the admin NSF and then sending out appropriate messages to the various deployment services. The fact that there's only one such deployment service currently doesn't diminish the splendidness of my mental model.
The reverse proxy implementations that I'd mentioned before haven't really changed much since I introduced them, but that's, I think, a good sign: they do what they're supposed to and don't necessarily need dramatic changes. The Domino-side reverse proxy - the one that lets your Liberty apps look like they're running inside Domino's normal HTTP server - has risen in my estimation since I made it, since it makes for a very-reasonable story. It's essentially like if you use the Equinox extension points to deploy a servlet or web application, except you trade the ability to run within a database context for a much-more-modern development environment.
The full list of closed issues for this release is available on GitHub, and I've uploaded the distribution to OpenNTF.