I did some work to get closer to making Log4j2 API work on Android. What remains is the dependency on the java.lang.management package in ThreadDumpMessage and ExtendedThreadInformation.
(Shameless plug) Every java main() method deserves http://picocli.info > On Jun 17, 2017, at 16:50, Mikael Ståldal <mi...@apache.org> wrote: > > I think Oleg have a point in that log4j-api is a bit too heavy currently. I > was maybe a mistake to put concrete implementations of Message and StringMap > there. > > The problem is not primarily the size, but that the implementation classes > drag in unwanted dependencies (like this RMI dependency). > > We cannot change that now (maybe for Log4j 3.0), but I think we should keep > that in mind and try to avoid adding more implementation stuff to log4j-api > in the future. > > And we should definitely make sure that log4j-api works smoothly on Android. > > >> On 2017-05-31 19:57, Oleg Kalnichevski wrote: >>> On Thu, 2017-06-01 at 01:18 +0900, Remko Popma wrote: >>> Oleg, >>> >>> Elements in the Log4j configuration can be instrumented with MBeans >>> to >>> allow remote inspection and modification of an application's logging >>> configuration. As Matt pointed out, this can be disabled. >>> >>> There is no dependency on RMI as far as I know. >> Remko, >> Lint code analyzer used by Android seems to suggest otherwise. >> java.rmi.MarshalledObject imported by SortedArrayStringMap does look >> like a direct dependency on RMI to me as well. >>> Was the above a conscious design decision? I did most of the work in >>> this >>> area and as far as I remember, yes. ;-) >>> >> Given we have established that I am not sure what your long term >> strategy towards Android is going to be. At the moment adding >> transitive dependency on log4j2-api causes any Android build to fail >> with a scary invalid package error. Surely this error can be ignored >> with a custom lint rule but it may present a certain reason for concert >> to less experienced developers. >>> Not sure what you mean by "heavy". From a user's point of view, more >>> functionality is often desirable. From an implementor's point of >>> view, care >>> was taken to provide abstract implementations that should make it >>> relatively easy to provide an alternative implementation of the >>> Log4j2 API. >>> There is some additional cognitive load because of the richer >>> functionality >>> but there is enough overlap with other logging frameworks that in >>> practice >>> I don't think this is a problem for users. >>> >>> The Message interface is a powerful abstraction that allows users to >>> create >> I have nothing against the Message interface as such. I am not not sure >> that all of its implementations belong to the facade APIs. That is all. >> Oleg >>> various enhancements without requiring API changes. It is one of the >>> things >>> that made it possible to make Log4j2 garbage-free in a backwards >>> compatible >>> manner. Compare for example with the SLF4J API which requires that >>> the user >>> logs String messages only. I personally think that was a design >>> mistake, if >>> only for the fact that a String-based API prevents garbage-free >>> logging. >>> The Message implementations simply cover a range of common use cases. >>> >>> Remko >>> >>> >>> On Thu, Jun 1, 2017 at 12:10 AM, Oleg Kalnichevski <ol...@apache.org> >>> wrote: >>> >>>>> On Wed, 2017-05-31 at 09:30 -0500, Matt Sicker wrote: >>>>> The JMX stuff can be disabled, and there are some other similar >>>>> optional >>>>> dependencies we've had to create due to some previously reported >>>>> issues >>>>> with missing classes on Android. As for full compatibility, I >>>>> don't >>>>> think >>>>> any of the main developers here have worked on that, but patches >>>>> and >>>>> other >>>>> contributions are welcome! >>>>> >>>> >>>> Matt >>>> >>>> I am perfectly fine with doing all the necessary leg work but first >>>> I >>>> need to understand if dependency on RMI and Management APIs was a >>>> conscious design decision or it simply happened. >>>> >>>> After having taken a cursory look at Log4j2 APIs I must admit I am >>>> bit >>>> unpleasantly surprised at how heavy they feel. For instance, was it >>>> really necessary to put all sort of concrete Message >>>> implementations >>>> into what is meant to be an abstract logging API? >>>> >>>> Oleg >>>> >>>> >>>>> On 31 May 2017 at 04:54, Oleg Kalnichevski <ol...@apache.org> >>>>> wrote: >>>>> >>>>>> Folks, >>>>>> >>>>>> I did try to do a reasonable research on the matter prior to >>>>>> posting my >>>>>> question here, nevertheless, please do excuse me if I am asking >>>>>> something obvious or well documented somewhere (in a place I >>>>>> was >>>>>> unable >>>>>> to find). >>>>>> >>>>>> I read that people had been more or less successfully using >>>>>> Log4j2 >>>>>> 2.3 >>>>>> on Android. >>>>>> >>>>>> In our case (Apache HttpClient 5.0) when the library gets >>>>>> pulled >>>>>> into >>>>>> an Android project, the Lint static code analyzer reports two >>>>>> severe >>>>>> violations due to transitive dependency through Log4j APIs 2.8 >>>>>> on >>>>>> Java >>>>>> RMI and Java Management APIs. >>>>>> >>>>>> My first question is whether or not Log4j2 has been built and >>>>>> tested >>>>>> for compatibility with Android of any version? >>>>>> >>>>>> Another question whether or not Logging APIs dependency on on >>>>>> Java >>>>>> RMI >>>>>> and Java Management APIs intentional? >>>>>> >>>>>> Oleg >>>>>> >>>>> >>>>> >>>>>
