28 December 2010

Architecture Rules

Gothic ArchitectureUnfortunately checking Java code for compliance with a given software architecture is not done on every project, as far as I know only a few experts do it. This is not good because "if it's not checked, it's not there". Free tool support for enforcing architectural rules has been lacking since long but recently things have changed. Well, maybe not recently but recently I thought about it :-)

There have always been a few basic tools to check the references of classes. One of these tools is Macker. It's quite old and not actively maintained any more, but I've been using it for years and it worked great for me. It's small and simple and yet immensely powerful. I love it and use it whenever possible. Everybody should use it. And don't turn it off!

A Shameless Plug
Macker and some other tools that can be used to enforce architecture rules are described in the fourth part of my 'Code Cop' series, published in the German magazine iX last summer: Automatisierte Architektur-Reviews (Automated Architecture Reviews) (iX 6/2010).

layersArchitecture Reviews with Ant
The article describes several free tools (PMD, Macker and Classycle) and how to use them with Ant to verify different aspects of an architecture. Each of them has its advantages and disadvantages and when used together they are useful. The examples of the Ant integration and the PMD/Macker/Classycle architecture rules as given in the article should help you getting started with your own checks.

Macker and Maven
As I said above, Macker comes with proper Ant support, but Maven integration has been lacking. Last year I wanted to use Macker on an Maven project but was disappointed by the immaturity of the MackerMavenPlugin available on Codehaus. So I had to enhance it a bit. I submitted some patches which got accepted but still the MOJO wouldn't get promoted out of its sandbox state. Fortunately I keep an unofficial release (0.9) in my own Maven repository. So finally proper Maven integration of Macker is available.

Other Tools
I guess there are other tools available to be used with Maven. For example there is Architecture Rules with its maven-architecture-rules-plugin which uses JDepend under the hood. It looks promising but I haven't used it in production yet. And I hear that Sonar 2.4 is able to check architecture rules as well but I didn't try it till now.

(List of all my publications with abstracts.)

16 December 2010


Last year, after commuting for more than ten years I got tired of reading on the train. I wanted to make better use of the time and got myself one of these small sub-notebooks. I chose an ASUS Eee PC S101. Although it's not very powerful it is able to handle small Eclipse projects. It's a slick device and I love it.

The Problem with SSDs
It contains a ridiculously small SSD hard drive, an "ASUS-JM S41 SSD". Recently after the drive was full for the first time, disc performance degraded catastrophic. Whenever the disc was accessed the computer would freeze one or two seconds. The whole device got totally unusable. I was already fearing the worst.

Backing Up MusumeTRIM to the Rescue?
When searching the web I learned that all SSD share the same problem of free space management which is fixed by the TRIM command. TRIM is a standard command defined by the (S)ATA specification. Unfortunately Windows 7 is the first version to make use of TRIM and there are no plans to port it back to earlier versions. (I also found references to WIPE but I don't know if it's a command some drives implement or just another name for the process of trimming.)

Vendor Tools
Some SSD vendors have noticed the need for SSD TRIM and provide tools of their own. Some vendors provide firmware upgrades like OCZ. Others offer special tools. For example there is a tool called wiper.exe provided for the G.SKILL Falcon drives and maybe some other drives by G.SKILL. Unfortunately wiper crashes when run on the Eee PC. Intel offers its own Intel SSD Toolbox but the TRIM option is not available when run on the Eee PC. These two were the only tools supporting TRIM that I could find. Bad luck here too.

I could not believe it. I didn't own the first SSD on this planet. How was I going to fix it? Format the SSD and install the OS all over? Not if I could help it. Probably I had not searched the web long enough...

Trim CastleFrom 0x00 to 0xFF
One entry in a forum suggested that Piriform CCleaner's Secure Wipe trims the disc. Well it doesn't but it seems that some SSDs reclaim a block when it's filled with some data and that's what Secure Wipe is doing. It overwrites all empty blocks. Someone has written a little program to do exactly that: "AS FreeSpaceCleaner with FF" (aka "AS Cleaner 0.5") is meant to work around not having TRIM and is like a generic wiper that works on any drive. It creates a big file and uses it to write zeros in all empty blocks. It has one option, to use 0xFF instead of 0x00 to fill these blocks. Some forum entries suggested that people have successfully used the 0xFF option to trim their SSDs.

Finally Whole Again
The short story is that I managed to restore performance of the SSD in my Eee PC using FreeSpaceCleaner.exe. The long story is as follows:
  • First I did a BIOS upgrade. Disc access might benefit from a newer BIOS. I'm not sure if it's part of the solution but now that it's done it's done.

  • Then I reduced disc writes as much as possible. I turned off the index service, removed the swap file and disabled the recording of the last file access. This is not related to restoring SSD performance, but it's supposed to keep it performing a bit longer.

  • After that I uninstalled all programs which I didn't need and used CCleaner to remove all temporary crap. I think it's vital to have as much free space as possible so the SSD doesn't run out of "clean" blocks too soon. Some forum entries suggested that it's beneficial to have at least 50% of the disc free.

  • In the end I used FreeSpaceCleaner with the FF option to wipe the SSD and it worked! At least it did something as SSD performance definitely improved after using it but I doubt it was able to do a full TRIM on the disc because I have to use it quite often.
So thanks to FreeSpaceCleaner the problem was solved. (Download FreeSpaceCleaner with FF)

15 December 2010

Code Quality Assurance v2

Last week I gave my presentation on code quality assurance, for the second time this year, and it looks like it will become an integral part of the lecture. That would be great. Maybe one or another soon-to-be developer will get interested by the ways of the craftsmanship and not become a Duct Tape programmer.

(Code) Monkey and some Duct Tape...I was quite nervous in the beginning of the presentation as I had never spoken in front of so few people :-) Honestly, giving it the second time helped me a lot and I was much more relaxed and didn't hide behind my laptop most of the time. There were few students, but they asked clever questions in the end. Only one student complained about too much mathematics needed to solve the prime factors kata. Well it's not that complicated, but maybe I will try the word wrap kata next time.

Dear Students
There is a list of references at the end of the slides, only a few but you should read them. Go ahead, read them now! I will wait here. If you are desperate you might listen to the recording of last year's quality assurance presentation. It's missing the demos, but my explanations should give you a general idea of what's going on. Good luck and don't succumb to the dark side!