Easy animations with Sproutcore 1.10

The release of Sproutcore 1.10 marks an important step in the life of this very popular framework. Lots of new features make developing applications on the Sproutcore framework even easier and fun.

One improvement that I am sure will catch your eye (pun intended) is view animations. Coding view animations was rather easy also on previous versions, but with 1.10 animations are now first class citizens bolted into the core rendering subsystem.
For an example of what is available out of the box see this demo.

So how would you use this goodness in an actual Sproutcore application? And how much code would it take?

As an example I have put together a very basic Sproutcore app (source, demo) which has two states: an authentication form and a main screen. Logging in transitions the app from the login form to the main screen and logging out returns the app to the login screen. Pretty simple.

Manage Windows printer event log settings from command line (i.e. GPO scripts)

Just a quick note to self that to enable/disable/query event log registration from the command line on Windows releases greater than XP and Server 2003 you can use the wevutil tool.

For example to enable logging of print requests on Windows 7 for auditing purposes:

wevtutil sl Microsoft-Windows-PrintService/Operational /e:true

The equivalent command for the the above on Windows XP is the following:

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Providers /v EventLog /t REG_DWORD /d 7 /f
net stop spooler
net start spooler

Developing Sproutcore apps on c9.io

The Cloud9 online IDE running on Chrome/Mac.

Today I was looking for a way to quickly edit a pull request to the Sproutcore project without booting up my laptop, but using the MacMini in the living room instead, which is always on, being our main entertainment system.

Turns out it's quite easy if you do not mind signing in into another online service: the Cloud9 online IDE.

Book Review: Instant OpenNMS Starter

Disclaimer: Packt kindly sent me a free copy for review.

TL;DR: Rating 4/5. Recommended for beginners and intermediate.

The book itself is short, but packed with information. A fast reader with some experience with OpenNMS should be able to finish it in 4 to 6 hours. Beginners will probably want to follow the pointers to the online documentation, check the configuration files and possibly experiment so they should allocate more time.

Before being published the book has been reviewed by Jeff Gehlbach. Anyone who has been involved with OpenNMS for some time know him, as he is one of the many brilliant minds working for the OpenNMS company, the commercial entity which develops and supports OpenNMS. Surely his involvement serves as a kind of seal of quality for the book. I for one was surprised by the clarity with even the most complex aspects of OpenNMS were presented in such a short text.

Instant OpenNMS Starter is divided in three main parts: installation, quick start and an advanced section that the book calls ‘the top 5 features’. The final section is a reference of sites and humans with more information on OpenNMS.

The author has been careful to link to the relevant sections of the online wiki when he felt that the wiki content was adequate, without devoiding the book of any additional practical information. For instance in the installation section he actually describes a more secure way of installing OpenNMS than that described in the online user guide and he does so by simply citing the extra steps while leaving to the online documentation to specify the rest.

The quick start section is useful for those in a hurry to just have something monitored with OpenNMS and needing to for a pointer on what all those links in the web ui do.

The advanced section is where probably you will spent most of your time as it describes the most interesting features of OpenNMS which are:

1. service assurance through polling
2. data collection through collectors
3. thresholds and notifications
4. events, alarms and automations
5. reports

IMHO one glaring omission in this list is the Provisioning system which was introduced with OpenNMS 1.8 and is a key feature because it covers a critical aspect: how nodes are added into OpenNMS for monitoring. I reread the book twice hoping that perhaps it was mistake on my part, but I could not find a single reference to it.

The book covers each of the five areas with enough depth to give a dedicated beginner useful pointers and background on how to implement the most advanced features of OpenNMS. The author again intelligently uses links to the online wiki to extend the text.
Only the section on reports felt a little thin. In defense of the author one could say that the reports area is so complex that it would have quickly grown out of hand for this kind of book. Perhaps in a second edition he should consider expanding it to at least mention the possibility of creating Jasper reports from collected data.

Instant OpenNMS Starter is clearly aimed at, and I recommend it for, people starting with OpenNMS, evaluating it or who might have inherited a working installation and now have to maintain it. Users seeking to master one of the 5 areas listed above should certainly consider buying it when the online bits and pieces feel not enough or too sparse.

By the title it should come as no surprise that advanced users are not likely to find any new or useful information at all, but, again given the price and the short text, it could still be used as a kind of self-check.

Update Oct/2/2013

There was a brief exchange of emails on the opennms-discuss mailing list with the author, I think it gives useful context to some of the items in my review. I reproduce it under here in full (link) :

Regarding Provisiond, I agree that it needs to be there. When I wrote the book I had to follow very specific guidelines from the publisher. In the top 5 features section I had to decide how to organize it. It was either going to be Capsd or the new and improved Provisiond as one of the 5. When I wrote it, Capsd was still enabled by default and I thought it was easier to get started with. If I would redo it now, I would change the section to Provisiond with a simple mention of how it evolved. In fact, I am preparing this very section now and will make it available on my site. Would be nice to have a revised edition though, I'll check with the publisher. Regarding reports I think it would be nice to have a similar short book of its own on the subject, going through OpenNMS' default reporting capabilities, more advanced custom JasperReports and maybe some modern ajax report dashboards built on top of the nice RESTful API (something I've been wanting to explore). Just thoughts...

Monitoring Oracle tablespace quota with OpenNMS

Going beyond the normal application availability check

One interesting use of the OpenNMS JDBC poller is for extracting data from the Oracle administrative database tables, for example tracking tablespace quota usage to detect quota exhaustion, sudden usage peaks and graph usage over time.

Graph of quota usage for user [redacted] on tablespace DAT.
Notice the cleaning operation running at 3.30 AM

Tablespace quotas is a feature present in the Oracle database that allows the DBA to set a limit on the amount of storage that any given user can consume on a specific tablespace. This allows the DBA to share tablespaces across users yet still be able to policy users into predefined usage boundaries. When a user consumes all its quota it can no longer store data, but it can delete it, thus allowing self-recovery.

A not so short guide to ZFS on Linux

Updated Oct 16 2013: shadow copies, memory settings and links for further learning.
Updated Nov 15 2013: shadow copies example, samba tuning.

Unless you've been living under a rock you should have by now heard many stories about how awesome ZFS is and the many ways it can help with saving your bacon.

The downside is that ZFS is not available (natively) for Linux because the CDDL license under which it is released is incompatible with the GPL. Assuming you are not interested in converting to one of the many Illumos distributions or FreeBSD this guide might serve you as a starting point if you are attracted  by ZFS features but are reluctant to try it out on production systems.

Basically in this post I note down both the tought process and the actual commands for implementing a fileserver for a small office. The fileserver will run as a virtual machine in a large ESXi host and use ZFS as the filesystem for shared data.

Development is fun again with nodejs

Being a longtime Java developer, back from when servlets where cool and Struts was making MVC popular among web devs, I always try to find new and more productive ways to deliver software within the Java ecosystem.

Recently I turned to Grails and delivered several projects with it. When developing with Grails you can use the power and the expressiveness of Groovy to write compact, elegant, fluent and readable code.
The downside is that Grails is huge:

1. even the most simple Grails apps will weigh in the 40MB range
2. compilation, test and building takes a long time (minutes, actually) even in recent versions
3. it is (fairly) complex, but that I can understand because it does so much
4. it will consume a huge chunk of you app server memory when deployed

I have been using Grails as the backend for Mappu too, initially just because I wanted to bootstrap the project quickly and Grails is simply perfect for that. But as time passed I started to find Grails too heavy for a simple REST API. I am currently running the demo on the smallest Rackspace server and it's constantly swapping. It's not slow, but it could be better.