Tag: programming

Fixing a Jenkins 1.5 Slave on Windows 2016

2018-01-01 rolfje No Comments

When you configure a Jenkins 1.5x slave on a Windows 2016 machine according to the instructions on wiki.jenkins-ci.org you will probably get a warning that the .Net 2.0 is not available. This is reported as issue 21484 and the fix is to upgrade, which sometimes can be a problem.

If you can’t upgrade to the latest version for whatever reason, you can easily fix the .Net problem by changing the jenkins-slave.exe.config file from:

&lt;configuration&gt;
  &lt;runtime&gt;
    &lt;generatePublisherEvidence enabled=&quot;false&quot;/&gt;
  &lt;/runtime&gt;
&lt;/configuration&gt;

To:

&lt;!-- see http://support.microsoft.com/kb/936707 --&gt;
&lt;configuration&gt;
  &lt;runtime&gt;
    &lt;generatePublisherEvidence enabled=&quot;false&quot;/&gt;
  &lt;/runtime&gt;
  &lt;startup&gt;
  	 &lt;supportedRuntime version=&quot;v2.0.50727&quot; /&gt;
     &lt;supportedRuntime version=&quot;v4.0&quot; /&gt;
  &lt;/startup&gt;
&lt;/configuration&gt;

Hope this works for you. Cheers!

Software

Mattermost Delete Channel “fixed”

2017-10-26 rolfje 41 Comments

Users of Mattermost have probably noticed the less-than-optimal interface design where de Delete option is right above the Leave option in the Channel menu. On a busy server, you can imagine having quite a few incidents where people accidentally completely delete a channel.

In the Open Source version of Mattermost, everybody van do anything, because there is no sensible security model with roles. Mattermost Inc. seems to think that the Open Source community is not entitled to roles, which I (and others with me) strongly disagree with.

Forking Mattermost, learning Golang and enabeling security, improving a few other issues for the open source community along the way is a plan. But there is a simpler workaround for people running Mattermost inside Nginx.

Software

Make the ESP8266 talk 9600 baud

2017-01-022025-10-17 rolfje 3 Comments

The default serial speed on the ESP8266 WiFi chip is 115200 baud. If you connect this chip to an Arduino and want to use SoftSerial to talk to it, it will not work. The SoftSerial library is limited to 9600 baud because of hardware limitations of the Arduino. If you want to talk to the ESP8266 with an Arduino at lower speeds, you need to tell the ESP8266 to slow down.

Hardware, Software

Solving the JAXB “unexpected element” problem

2015-06-08 rolfje 2 Comments

If you are using JAXB in a maven/java project to unmarshal an XML document and you get:

javax.xml.bind.UnmarshalException: unexpected element (uri:”urn:iso:std:somestuff:xsd:somestuff”, local:”Document”). Expected elements are (none)

Or if you are using JAXB to marshal an XML document and you get:

com.sun.istack.internal.SAXException2: unable to marshal type “generated.somestuff.Document” as an element because it is missing an @XmlRootElement annotation

You have probably fallen victim of the fact that JAXB does not do “Simple Binding” by default. If your project is a maven project and you generated classes based on an xsd file, this is how you fix it (without changing the xsd file):

Software

Import/export an Oracle Schema using JDBC

2015-01-02 rolfje No Comments

When doing integration testing or fixing a bug in a piece of Java code that uses Oracle as a database, being able to do quick exports and imports of your schema can be a big help. Sometimes just calling Oracle’s imp/exp commandline tools from your code can be of help, but I was looking for something a bit more portable and less demanding on my local development machine. I found that Oracle’s datapump functionality can be called from stored procedures, which in turn can be called from a normal JDBC statement.

Software

Arduino and the QVGA 2.2″ TFT SPI screen

2014-11-17 rolfje 5 Comments

I went through all the struggles everybody else seems to be going through to get this screen connected to my Arduino Nano. I had the 5V to 3.3V voltage conversion problem, and the “only works with software interrupts” problem which makes the display run slow. The solutions are not complicated but not very wel documented. Until now.

Hardware, Software

Open a port in OSX Mavericks’ Firewall

2014-05-10 rolfje 10 Comments

The new firewall in Mavericks is great. For the common user. For a developer, not so much. If you are a Java developer like me, and you just need to open one port (say, 8080) so that the web application you’re working on is accessable from another computer, you can’t. I disabled the Firewall altogether for a few days, but it didn’t feel right.

I googled around and to make a long story short, here’s how to open port 8080 on any interface to any application on your OSX Mavericks installation in 3 steps:

sudo vim /etc/pf.conf

Then add the following lines at the end of the file:

# Open port 8080 for TCP on all interfaces pass in proto tcp from any to any port 8080

Test (and, according to the documentation, load) your edits with:

sudo pfctl -vnf /etc/pf.conf

Reboot.

(I have found at least 5 pieces of voodoo to make the Firewall restart and reload, but none of them seemed to work reliably, so pardon the reboot)

You can close it by commenting out the lines in pf.conf and reboot again. If anybody knows of an easier way to do this, preferably in one terminal command, and without rebooting, let me know.

Hope this helps.

Software

Anonimatron: Quick Start

2013-11-03 rolfje 18 Comments

After reading my last blogpost on Anonimatron, you must have asked yourself “Great, but how do I actually use Anonimatron to de-personalize my database”? I tried my best to make basic Anonimatron configuration as self-explanatory as possible, just start it without any command line arguments and it will tell you.

Less adventurous or in a big hurry? This blogpost will show how simple it is to install and configure Anonimatron on an example MySQL database.

Read More “Anonimatron: Quick Start” »

Software

Anonimatron: Overview

2013-10-31 rolfje No Comments

In every software project, there comes a time where a bug pops up, nobody knows how to reproduce it, and somebody says “I know, let’s test this against a copy of the production database”. Even with the best intentions, once production data leaves the production machine with all its safeguards it becomes really hard to do access control on that data.

Most of the time, it’s not even needed to have that data. Developers just need a data set which resembles the production scenario close enough. Some brave souls have mixed succes with data generators, but those generators usually are tedious to maintain and die a slow death under the pressure of the daily grind.

In some ambitious projects automated integration testcases are built on top of the data which was inserted by the data generators. As the generators die, so die the tests. If you recognize this pattern, Anonimatron might be the answer for you.

Read More “Anonimatron: Overview” »

Software

Non-Java Binary Dependencies in Maven

2013-07-18 rolfje 9 Comments

Suppose you have a Java Server application, and some of the runtime binaries in that application are external to your application. Generated image files, compiled Silverlight components in your pages, or resource files which are managed by an external team.

Much like the jar files used by your application, these external binaries can be seen as dependencies, with versions. This blogpost assumes your project is built with Maven 2, because the real world isn’t always a greenfield project.

Because Maven is designed around jar file dependencies, and a lot of it’s internal decisions are based on file extensions, it looks like this problem can not be tackled with Maven. But there is a way to do this. It will decouple your sub-projects and make version and dependency management much better.

Software