The Fast Country

« May 2005 | Main | July 2005 »

June 28, 2005

More Virtual Machines

Virtual machines seem to on people's minds a lot recently. Over at blogs.sun.com, Eric Schrock has a great post on the virtualization work taking place in OpenSolaris.

Posted by JohnC at 11:50 PM | Comments (0)

June 22, 2005

Billy Corgan

On Friday evening, I went to see Billy Corgan, of Smashing pumpkins fame, play in the Ambassador. It was a superb gig. It started with a pretty decent support band called Gliss. This young, three member band opened the concert with some energetic rock and had an amusing habit of swapping instruments. Though all played well, Victoria, their redheaded bass player, was much better than the two guys. Amusingly so, in fact.

Gliss had a decent light show. It looked, to me, like they were using Billy Corgan's setup, with atmospheric lighting through a lightweight backing curtain. I was wrong. Before Mr. Corgan came on, the entire stage was cleared. The backing curtain was removed to reveal a wall of reflective white tiles. The carpet where Gliss's drum kit had been was lifted to reveal a reflective white floor. Two keyboards, decorated to look like silver hand basins, were placed on the stage. Some microphones, an iMac and an electric drum kit completed the furnishings. The stage looked vaguely like a stylish bathroom. As the band came on stage moving lights at the front silhouetted them against the tiles, which reflected the colour of the lights. That was impressive. Then one of the tiles lit up bright green. As the band played, more tiles lit up as bright green pixels. Then the pixels started to move. It turned out that the tiles were pixels in a video screen and we were treated to animations on that screen for the rest of the concert. That was very impressive.

The music itself was very good. All the songs had a freshness while at the same time feeling familiar. They are like classics sprung fully formed from Billy's brow. The tempo varied from the fast paced Mina Loy, A100 and Walking Shade to the slower Now (And Then) and the wonderful cover of To Love Somebody. There were no Smashing Pumpkins songs, at least no whole ones. The first nine notes of Today were slipped into the middle of one song, which earned a roar from the crowd. However, the classic Pumpkins tunes were not missed. The new songs really were that good. In fact, I was impressed enough to buy the album, The Future Embrace, the next morning.

Posted by JohnC at 12:33 AM | Comments (0)

June 06, 2005

The Wicklow Way

The Saturday before last I went on my third hike. This one took the four of us along a portion of the Wicklow Way and up to the top of Djouce. The walk was not as long as previous walks: we walked about 9 km. However, there was about 450m of height gain, so we got a bit of exercise. We started at one of the car parks near Long Hill and ended up at the car park overlooking Lough Tay. The weather was bright but very windy.

It was an easy walk. The Wicklow Way is very popular, so to prevent erosion a path or railway sleepers has been laid as a path. So no stepping over heather, climbing out of bog holes, or wading streams this time. We did have a stiff breeze though, especially at the top of Djouce. The wind was strong enough to lean into and get to stand at an angle. A peculiar feeling that. There were some great views too.

The walk would have been the perfect if I hadn't had my accident on the way back to the car. About 400m from the car, a gust of wind caused me to stumble, and I sprained my ankle. The sprain wasn't bad so I made it back to the car without too much trouble. However it was a disappointing end to a fun hike.

Posted by JohnC at 12:52 AM | Comments (1)

June 01, 2005

Virtual machines

I have been working writing PHP code, in work, for the past few months. This has been quite interesting and I have learned a heap load of new things. However, I am starting to miss Java. It is not the language that I miss most or the class libraries, though I do miss them. What I miss most is the virtual machine (VM).

Aside from security and portability, which are taken for granted, there are a few cool things that the Java VM enables. For example, the code it runs is byte code, an intermediate form between high level computer languages and machine instructions. This byte code is normally compiled from the Java high level language. It doesn't have to be, though. Other languages can be compiled to Java VM byte code. There are two active projects doing just that: Groovy and Jython. Jython is especially interesting, as it is a compiler/interpreter that brings python to the Java VM. People I know have been ranting about python for years. There is also NetBeans support via Coyote.

The other cool thing that the Java VM allows is for instrumentation. The virtual machine provides a layer of indirection where instrumentation can go, for example to allow profilers and debugging tools to plug in. Java has really good interfaces for this sort of thing. The Java Platform Debugging Architecture (JPDA) is really powerful. There is a C interface for writing debugger modules (JVMDI), a protocol which allows a debugger to connect to a Java VM over the network (JDWP), and a Java class library for debugging events (JDI). I have used the Java Debugging Wire Protocol (JDWP) a lot via the NetBeans debugger and it is really useful. I plan on using the other two interfaces in the near future too, especially JDI. When I do, I will post here with my experiences. Debugging support isn't the only thing that can be added in the Java VM layer: profiling support can be added too. The Java VM Profiler Interface (JVMPI) allows profiling modules to be created and this is the interface that the DTrace VM agent uses. I haven't used this yet but I know it will be really handy some day.

Virtual machines seem to be fashionable at the moment. IEEE Computer magazine for May 2005 has a number of feature articles on virtual machines and virtualization. The articles are online, but only the editors' introduction can be downloaded without an IEEE membership. They are very informative articles, which give a broad introduction to what virtual machines are and the types of virtual machine available. The articles pointed to numerous examples including open source system VMs like XEN, User Mode Linux, and VServer. Add in Solaris Zones and I guess that means I have loads more reading to do on virtual machines.

Posted by JohnC at 12:45 AM | Comments (0)