> Am 05.07.2017 um 11:27 schrieb Stephen Connolly > <stephen.alan.conno...@gmail.com>: > > +jenkins-dev
Uups, sorry… > > On 5 July 2017 at 02:13, Ullrich Hafner <ullrich.haf...@gmail.com > <mailto:ullrich.haf...@gmail.com>> wrote: > >> Am 04.07.2017 um 18:44 schrieb Stephen Connolly >> <stephen.alan.conno...@gmail.com <mailto:stephen.alan.conno...@gmail.com>>: >> >> Ulli, >> >> What do you think on this proposal, given that you have contact with a lot >> of students who have been trying to get to grips with the Jenkins code base. >> >> Would it make their task easier? >> > > Up to now most students work in the area of testing (ATH), so this will not > help them (they would love to see IDs for all entry fields, but that is a > totally different topic). > > So one aspect where this could help is in knowing what to test. > > The annotations can be used to help identify the intent of the plugin author > / core and we could perhaps even develop tooling to identify ATH coverage > > >> -Stephen >> >> On 3 July 2017 at 05:21, Stephen Connolly <stephen.alan.conno...@gmail.com >> <mailto:stephen.alan.conno...@gmail.com>> wrote: >> I have been developing Jenkins plugins and changes to Jenkins core for more >> than 10 years now. As such, I have internalized a lot of the knowledge about >> how to develop against Jenkins and more specifically against Stapler. >> >> When I talk to people trying to start out development against Jenkins, the >> magic of Stapler seems to be a big source of confusion - at least to the >> people I have talked to. >> >> Prospective developers get confused: >> >> between primary facets and facet fragments. >> where to put facets and facet fragments. >> which facet fragments are optional and which ones are mandatory >> > > This indeed is one of the most confusing things when developing plug-ins. It > cost a lot of time to get these things right (mostly by copying and pasting > code from another plugin). > > I'm not sure if annotations are the correct way of dealing with these > problems. I think you then need to know where to put an annotation and where > not, this will also result in searching for other plugins that do it right. > > Yes, I would also propose improving the stapler documentation in conjunction > with these changes so that it should be easier to find the "recommended" > patterns to follow. > > Though how much energy I personally have to push documentation improvements > is another question entirely ;-) Well, this is always a problem ;-) But we already have some good examples in the wiki so the documentation of these new concepts might grow in the same way by some motivated plugin authors ... > > > >> (Did you even know that those jelly / groovy views are called facets and >> that there are two kinds?) >> >> Some of those concerns affect me too... but I am a seasoned Jenkins >> developer CMD+SHIFT+P, *, ENTER and IntelliJ is showing me a full list of >> facets and facet fragments from the class hierarchy and I can search each >> one looking for the <st:include page="fragment" optional="true"> to discover >> that there is an optional facet fragment... and then try and dig through the >> Jelly / Groovy logic to determine when and why that fragment should be >> included. >> >> It doesn't just stop there... There are those methods that we expect Stapler >> to invoke for us... typically they are the doFillXYZItems() or doCheckXYZ() >> methods. I find myself having to mark them up like: >> >> @SuppressWarnings("unused") // stapler >> public FormValidation doCheckWidgetValue(@QueryParameter String value) { >> ... >> } >> >> So that my IDE stops complaining about the dead code. It's not a big deal in >> the grand scheme of things, but I'd much rather have an annotation on the >> method to signify that we expect the method to be used by stapler... Right >> now I could do that using >> >> @WebMethod(name="checkWidgetValue") >> public FormValidation doCheckWidgetValue(@QueryParameter String value) { >> ... >> } >> >> If I don't like that, I guess I could use the newer HTTP verb annotations in >> stapler: >> >> @GET // stapler >> public FormValidation doCheckWidgetValue(@QueryParameter String value) { >> ... >> } >> > > But do these annotations help to get rid of the unused code warnings? I think > you still need to add a @SuppressWarnings. > > Well you can configure IDEs to say "this annotation is used" and we can even > have the Stapler plugin for IntelliJ pre-register the annotations so that > IntelliJ users (I'm selfish ;-) ) don't even need to add the setting That would be very helpful! (Isn’t everybody using IntelliJ to develop plugins?;-) Maybe improving the Stapler plug-in would be a good candidate for a bachelor/master thesis… (Code completion in jelly views would be awesome) > > >> But the simple @GET is not screaming out stapler to me, so I feel compelled >> to add a // stapler comment to remind myself that the annotation is used by >> stapler >> >> Then we hit the actual name that stapler exposes things on. There are some >> conventions that stapler follows... and they are magic conventions... so >> much so that I just keep http://stapler.kohsuke.org/reference.html >> <http://stapler.kohsuke.org/reference.html> as the first bookmark in my >> bookmark bar. >> >> I think we can do better. I think we should do better, and here is my >> proposal. >> >> We should introduce some annotations. Make them available against older >> versions of Jenkins so that we don't have to wait for everyone to update >> their plugin baseline. The annotations can be added as a plugin dependency >> in the parent pom, that everyone can use them just by upgrading the plugin >> parent pom. >> >> Here are the class annotations I think we need: >> An annotation (I propose @StaplerObject) that says "This object is expected >> to bound to a URL by Stapler, the Stapler annotations are complete, check >> that there are no facets / fragments without a corresponding annotation and >> no magic on this class please" (so if there is, say a rename.jelly but no >> @StaplerFacet("rename") or @StaplerFragment("rename")then you get an error) >> An annotation (I propose @StaplerFacet and the repeatable container >> @StaplerFacets) that says "Here are the facets that this object is expected >> to have" (doesn't have to be on a @StaplerObject but when not on a >> @StaplerObject we can only check for missing expected facets, we cannot >> check for "unexpected" facets - i.e. I created a facet with a spelling >> mistake or typo in the name) >> An annotation (I propose @StaplerFragment and the repeatable container >> @StaplerFragments) that says "Here are the facet fragments that this object >> is required or may optionally have" (quite often will not be on a >> @StaplerObject) >> >> So I envision something like this (pre-Java 8): >> >> @StaplerObject >> @StaplerFacets({ >> @StaplerFacet("index"), >> @StaplerFacet("config") >> }) >> @StaplerFragments({ >> @StaplerFragment("main"), >> @StaplerFragment("side-panel"), >> @StaplerFragment(value="tasks",optional=true) >> }) >> public class Widget { ... } >> >> When compiled targeting Java 8 this would become: >> >> @StaplerObject >> @StaplerFacet("index") >> @StaplerFacet("config") >> @StaplerFragment("main") >> @StaplerFragment("side-panel") >> @StaplerFragment(value="tasks",optional=true) >> public class Widget { ... } >> >> There would be an annotation processor that could do some checks: >> If you add @StaplerFragment(..., optional=false) then any non-abstract class >> must have that fragment somewhere in the class hierarchy >> If you add @StaplerFacet then any non-abstract class must have that fragment >> somewhere in the class hierarchy >> If you add @StaplerObject then only the named facets and facet fragments >> must be present for that class (to catch somebody calling the facet resource >> with an incorrect name - it should be side-panel2.jelly but they called it >> sidepanel2.jelly) >> >> Then, while we are at it, I'd also like to add method / field annotations: >> An annotation (I propose @StaplerPath and the repeatable container >> @StaplerPaths) that says "here is the URL segment names that this method / >> field matches when Stapler is binding the URL". This annotation can be used >> to enable easier refactoring without risk of breaking the URLs because we >> can rename the getters and keep the URL scheme as before or even keep the >> legacy URLs but direct to the new URLs via the UI. >> Annotations (I propose @StaplerHEAD / @StaplerGET / @StaplerPOST / >> @StaplerPUT / @StaplerPATCH / @StaplerDELETE plus non standard methods >> supported with @StaplerMethod("...") and then a repeatable container of >> @StaplerMethods - the repeatable container would only take @StaplerMethod >> annotations though) that cover the different HTTP methods (a.k.a. verbs) - >> we have some existing, but they need some extensions and I think it might be >> a good idea to consolidate the names, especially if we want to allow >> consumption on older baseline versions of Jenkins >> >> So this could be something like this (Pre Java 8): >> >> public class Widget { >> @StaplerPath >> public Manchu manchu; >> >> @StaplerPaths({@StaplerPath,@StaplerPath("fu")}) >> public Foo foo; >> >> @StaplerPath >> public Bar getBar() { ... } >> >> @StaplerPath(StaplerPath.DYNAMIC) >> public Object getDynamic(StaplerRequest req) { ... } >> >> @StaplerPOST >> public HttpResponse doActivate(StaplerRequest req) { ... } >> >> @StaplerPath(StaplerPath.DYNAMIC) >> @StaplerPUT >> public HttpResponse doDynamic(StaplerRequest req) { ... } >> } >> >> Or targeting Java 8: >> >> public class Widget { >> @StaplerPath >> public Manchu manchu; >> >> @StaplerPath >> @StaplerPath("fu") >> public Foo foo; >> >> @StaplerPath >> public Bar getBar() { ... } >> >> @StaplerPath(StaplerPath.DYNAMIC) >> public Object getDynamic(StaplerRequest req) { ... } >> >> @StaplerPOST >> public HttpResponse doActivate(StaplerRequest req) { ... } >> >> @StaplerPath(StaplerPath.DYNAMIC) >> @StaplerPUT >> public HttpResponse doDynamic(StaplerRequest req) { ... } >> } >> >> The annotation processor can then give additional checks: >> >> @StaplerPath annotated fields must be public >> @StaplerPath(altName) annotated fields are only allowed if targeting a new >> version Stapler that adds support for that (unless the name is the inferred >> name) >> @StaplerPath annotated methods must be public and either match one of the >> allowed getter signatures or also have a HTTP method annotation and match >> the allowed action method signatures. >> @StaplerPath(altName) annotated methods are only allowed if targeting a new >> version Stapler that adds support for that (unless the name is the inferred >> name) >> @StaplerHEAD / @StaplerGET / @StaplerPOST / @StaplerPUT / @StaplerPATCH / >> @StaplerDELETE annotated methods must be public and match one of the allowed >> action method signatures. The method name must match the convention for >> action method inference (subject to @WebMethod(name="...") overriding when >> compiling against older versions of Stapler - but it would be an error to >> use @WebMethod if compiling against newer versions of Stapler because we can >> move to the new annotations in those cases) >> If the class is @StaplerObject annotated we can do additional checks for >> overlapping facets, for example where an action method or a getter will hide >> a facet (it's ok to hide the facet for non HEAD/GET requests though) >> There are probably additional checks that we can add as we figure them out. >> > > > Would there be some checks, that check for the correct path for the > corresponding index.jelly, config.jelly, global.jelly and so on? > > Yes, the idea is that when you annotate a non-abstract class with > @StaplerFacet we would check you have the facet in your class hierarchy and > error out. > > If you annotated your non-abstract class with @StaplerObject then we can go > one further and error out if you have an unexpected .jelly or .groovy file > which gives you even more help to avoid creating resources in the wrong place. > > Because of taglibs, and semi-static resources we cannot scan the classpath > for .jelly and .groovy files and assume that they are either facets or > fragments which is why the "is a complete set" checks require @StaplerObject > > >> Now there are some open questions: >> Does it make sense to start all these annotations with Stapler? My initial >> stab at this was to use @Staple in place of @StaplerPath and to re-use the >> @GET / @POST / @PUT / @DELETE verbs but mandating the @Staple annotation so >> that you would have: >> @Staple @POST >> public HttpResponse doActivate(StaplerRequest req) { ... } >> >> rather than >> >> @StaplerPOST >> public HttpResponse doActivate(StaplerRequest req) { ... } >> >> One of the issues I found with that is class conflicts when back-porting the >> @GET / @POST / etc annotations, so we could only use those if we were >> prepared to mark 2.7 as the oldest core that could use the annotations, >> whereas we can make new annotations in a separate package available as far >> back as Stapler 1.180 == Jenkins 1.455 (or worst case Stapler 1.237 == >> Jenkins 1.651) >> >> Now we could introduce new annotations without the @Stapler prefix, but then >> your code complete would confuse you between >> @org.kohsuke.stapler.annotations.GET and @org.kohsuke.stapler.verbs.GET plus >> we still need something to give a hint that the annotation is implying >> Stapler's involvement (at least from my perspective) >> I had thought about saying that the class level @StaplerObject should be >> enough of a flag that you should expect the other annotations... but the >> class annotation will be inherited, so you may not see it until you look at >> the super-class... and @Path will conflict with java.nio.file.Path... that >> might work with @Staple (and @Staples as the container) but while cute they >> do not scream to the new developers that these are involved in url binding. >> NOTE: In this context I see this change as being entirely opt-in. Plugin >> developers should not have to go adding the annotations - though we would >> probably apply them in Jenkins core to assist new developers. >> If we go with the Stapler prefix, would it make sense to consolidate all the >> annotations with that prefix? >> >> I am not convinced for the case of @ExportedBean and @Exported, these >> reflect a different cross-cutting concern and as such the pair seem named >> well from my PoV >> The @JavaScriptMethod / @WithWellKnownURL annotations might be worthy of >> consolidation if we can determine better names. >> The parameter binding annotations such as @AncestorInPath, @Header, >> @QueryParameter and @InjectedParameter I think are fine where they are as >> they will only be on an action method which already has the @StaplerPOST etc >> indicator. >> The meta-annotation @InterceptorAnnotation should not be consolidated, in >> any case we could not consolidate it and retain usage against older cores >> The other annotations are likely rarely used, but if we can find good names >> and people think they are generically useful rather than single use-case >> hacks added into the stapler API, I think consolidation might make the >> features more widely used. >> So, over to you the community of Jenkins developers: >> Would this change have helped you get started quicker? >> Would this change help you even now? > > I’m not sure if it would help to get started quicker. I think the UI mapping > in Jenkins is still (too?) complex even with these annotations. Maybe it > would make sense if you can show for an example plug-in class (and jelly > file) how it will look after using the annotations? > > Yes, my next step is to mock up the proposed annotations and apply to one or > two sample plugins as a (do not merge) PR. > > Do you have any plugins or plugin classes you would like to suggest as good > examples to trial? My plugins are typically too complex as a starting point for beginners (due to the analysis-core dependency and the number of implemented extension points), so it might be better to start with a simpler one. > > >> How ugly are my proposed annotation names? Can you provide a less ugly >> scheme of names? > > The names are fine. > > Thanks, one of the concerns I have is that we need some rough consensus on > the names as they are liable to become a bikeshed painting exercise >> Anything else? >> Stephen -- You received this message because you are subscribed to the Google Groups "Jenkins Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to jenkinsci-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/jenkinsci-dev/8B749EE4-C9A9-4B65-B4E9-5369EA3282EF%40gmail.com. For more options, visit https://groups.google.com/d/optout.
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