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From "Joachim Lindenberg" <>
Subject AW: [ANNOUNCE] Apache Guacamole 1.0.0
Date Mon, 21 Jan 2019 06:49:09 GMT
Hi Mike, Nick,

just wanted to tell that I got my extension code fixed and it now works with 1.0.0. Thanks
for spotting the issue and the hints.

Thanks & Best Regards, Joachim


Von: Mike Jumper <> 
Gesendet: Montag, 14. Januar 2019 06:44
Betreff: Re: [ANNOUNCE] Apache Guacamole 1.0.0


On Sun, Jan 13, 2019 at 12:11 PM Joachim Lindenberg < <>
> wrote:

Hi Nick,

thanks. I am attaching my source code. You´ll likely notice, Java is not my favorite programming
language, but anyway. Testing the code could be more challenging. My software is available
from, and the integration is documented at
(replacing 0.9.14 by 1.0.0)... I actually also have some unit test classes but removed them
do to passwords etc.


The goal of the extension is that my customers can fire up a virtual machine out of their
backups of windows systems. E.g. in case their laptop is lost, they can access the most recent
version from another system (keyboard and screen resolution makes sense though). There are
multiple ways to start – via guacamole entry point, via my web  ui, and via the windows


This error points you exactly where you need to look - there's a NullPointerException occuring
in the file, in the init() method, on line 128, which is called
by the SimpleConnection connection() method, on line 124, etc.  You need to trace back why
something null is being passed there (presumably from your custom extension) and correct that



You are passing a null GuacamoleConfiguration to the constructor:


As for your overridden connect(GuacamoleClientInformation info, Map<String, String>
tokens) method, that is not being called because that is not the prototype of that function.
The prototype has changed on git master, yes, but this API change was not part of 1.0.0. The
connect() for Connectable in the 1.0.0 extension API only takes a GuacamoleClientInformation.


Since your connection is based on SimpleConnection, you're not actually overriding a method
of SimpleConnection, but adding a new method which isn't used elsewhere. The original connect()
function remains unoverridden and continues to be called.


I suggest wiping out your local Maven repository and rebuilding your extension. I haven't
looked at your code, but assuming you're using a proper @Overrides annotation, I suspect your
code won't compile due to there being no such function to override. If you recently built
from guacamole-client git, your local Maven repository likely has a git master build of guacamole-ext
(which would still have the 1.0.0 version number), not the guacamole-ext which is part of
the 1.0.0 release and on Maven central.


Sure, but why is not my overridden method called? I want to do some magic (starting virtual
machines) behind the scenes. This actually took most of the time to figure out what call sequence
on which objects is done and where I can intercept – and then I didn´t really spend time
to clean the code up once I got it to work – and also I see that would probably have been
waste as now the inner logic changes.


There are *many* things that have changed between 0.9.14 and 1.0.0, and pretty much of all
of those changes are intentional :-).


Sure, but what I kind of miss is a docuemtation what changed for extension coders and how
to adopt to the changes. Or did I miss that?



Yep. What you're looking for is the "deprecation / compatibility notes" section of the release
notes. We write one whenever a release breaks compatibility in some way with a past release,
including changes to the extension API:


The changes to SimpleUser and the Simple*Directory classes are deprecations and don't break
anything directly. Your code will produce warnings during compilation, and you should migrate
when possible, but it should continue to build:


There are changes to the User interface which would break the build for you if you implemented
User directly, but users of AbstractUser or SimpleUser should be unaffected. Default implementations
of the new functions are provided:


If you continue chasing things down and things still aren't working for you, I suggest bringing
this over to a new thread on the <>
 list. The release announcement on the user@ list was meant to be just that - an announcement.
It is probably not the best thread for a development discussion.


- Mike


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