Apps as containers (by alaric)

As I have mentioned before, it annoys me that many applications try (subtly or otherwise) to appear as the 'containers' of your data; they are both editors of a particular type of object, and a browsing/management interface for that type of object. The insidiously widespread case being applications that have 'Open' and 'Save As' menu items that pop up mini filesystem browsers, only showing the types of documents that application cares about and hiding others.

Read more »

Is it normal to want to assign every object you own a serial number, then keep a database? (by alaric)

I've been doing some systems work in a rack recently that uses redundant systems. Two optical fibres come into to two switches which are connected to two routers and two load balances, and every server has two or more network interfaces (since there's internal and external VLANs).

So there's rather a lot of cables in there! Since the spare length is all neatly bound into a bundle, finding the other end of the cable you're looking at is a bit of a pain.

So I'd like to number each cable, label each end of the cable with its number, and add cable numbers ot the "what's in what port of which switch" spreadsheet.

Most cable marking systems, however, have to be applied before the plugs are attached to the cable - since they involve a sleeve that goes over the cable. This isn't good, since I want to label existing cables.

Hunting about online, I found these folks who do a nice line of markers - including the PC range of snap-on markers for existing cables. Lovely!

They've sent me a pack of samples, so I can experiment to see what fits best on my cables:

...and it looks like PC40 is the best size for CAT5 UTP.

CSS (by alaric)

I read this interesting article, which I found via reddit:

Lexical File Names in Plan 9 or Getting Dot-Dot Right

I found I liked the styling. At first I'd assumed it was a PDF, since it looked like the output of TeX or Lout, but it was suspiciously in a web browser rather than a PDF viewer.

"Oooh," I thought, "I wonder if the CSS they used for that is freely licensed? I'd quite like to use it to give my own writings that academic feel, so that people trust them uncritically, thus advancing my world domination plans."

But upon viewing the source, I had a nasty shock - every element was individually styled with its own style= element. Ugh. Looked like something had autogenerated it, most likely from something intended to be turned into a PDF. The result looked lovely, but was implemented terribly.

So I decided I'd sharpen my decidely rusty CSS skills a bit by cloning it properly.

The end result isn't a perfect copy, but looks good enough for me, and I'd like to share it if anybody else wants it. Here's a sample of it in use. And feel free to download and copy the CSS, subject to the nice license at the top.

C (by alaric)

I spent a lot of time programming C in my youth. I went through the canonical route; BASIC on an 8-bit home micro, moving up to Pascal then C when I managed to obtain access to implementations of either. At the time, conventional wisdom was that C was the best language about; the easy access to the underlying model of memory as an array of numbered bytes allowed the programmer to write efficient code to perform low-level data processing operations. The mantra was that there was a tradeoff between expressive power and safety; languages like Pascal made it harder to shoot yourself in the foot, at the cost of preventing you from doing interesting things.

But, with the advent of an Internet connection, I gained access to non-mainstream languages, and my explorations of the wider world of programming language technology began. I still dabbled in C or C++ from time to time, when the situation demanded it, but never on very complicated projects.

Recently, though, I've been working on a large C project. And I've found that I'd quite forgotten just how horrible it is in comparison to the languages I've been using recently...

Read more »

Replicated data (by alaric)

The project I'm currently working on is to build a replicated database; and, of course, this gets me thinking about TUNGSTEN, my own replicated database design.

Now, a fully-replicated database like the one I'm writing works by multicasting write operations to every node, so that each node has a copy of the entire database. This means that you can increase your read capacity by just adding more nodes and spreading the work between them. Each node can read its local database independently of the others, so there's no inherent limit to how many reads the cluster as a whole can do in one second. As long as you have unbounded money and space to keep adding more nodes.

However, since writes get multicast to every node, there comes a point at which your write load is the highest the weakest node in the system can keep up with. Adding more nodes doesn't help, since every write still happens on every node. The cluster as a whole has a maximum write capacity, regardless of the number of nodes.

So this system will do for now, but the next big bit of work on it will be to increase the write capacity - by partitioning the data set.

Read more »