April 2003 Archives

The Apache web server is argueably the coolest thing since sliced bread. On a site I maintain, we have archives of a few public mailing lists. I originally set these up to get mail out of my own in box, and found that it was convenient to have the resources close to me on the web. Subsequently, I have added a search feature and opened it up for public access.

We keep one year's worth of messages to each mailing list. If for instance you wanted to see our MySQL list archives, you would use this URL:

http://www.jsw4.net/info/list-archives/mysql/

Apache has a default module called autoindex_module, and in general, if the server cannot find a document named index.html in a directory that is publically accessible, it will construct a listing of the files in that directory. (Or sometimes, it will tell the viewer they don't have permission to view the directory. It depends on the site specific configuration.)

I've frequently wanted to change the order that the listing is shown in. For instance, the names in the directory above sort from oldest to newest at the bottom of the list. But users will most frequently want to see the recent entries first.

In noticed the listing is rendered with hyperlinks for column headings. To my pleasure, the interface is as you would expect it (if you know that at least one OS I use allows file lists to be sorted by clicking on the heading of such lists) and by clicking on the name heading I was able to change the default sort order from ascending order of names, to decending order. Notice the URL change that has occured:

http://www.jsw4.net/info/list-archives/mysql/?N=D

By reading the docs, I learned that one can also change the default sort order in the Apache configuration file, by use of the IndexOrderDefault Ascending|Descending Name|Date|Size|Description configuration directive.

Hats off the the folks at Apache, again.

Free Linux still exists. www.debian.org This is Good Stuff (tm), but it's not for the timid.

RedHat has not been free for me since my first Linux Box. (Once Mark used his media to install it, and I borrowed Frank's media once for the same box.) I've always tried to buy a copy of each major version, because I supported this vision of an operating system for the masses. I sometimes bought two back when they were $50 per boxed set.

Now they have this thing called RedHat Enterprise Linux, and the entry level server product costs $350. - $600. depending on what option you get. If you want multiprocessor support for 8 CPUs and up to 16GB of memory, they're looking for $2,500 for the premium edition.

One can still get RedHat Linux, the current flavor is 9 and MSRP is $165 for the Professional version. (And you can get it for free, all you need to do is download 3 CD images. It's usually cheaper to buy the retail box in the final analysis.)

That's the easy part. The upfront price is a fairly small part of the equation a lot of small businesses who have made a commitment to RedHat currently face.

To understand what these decisions may cost over time, one needs to look at maintenance, and the useful life of the product.

As noted above, RedHat does not require you to purchase a license in order to run the operating system, but in order to use their RedHat Network, (RHN) you must pay a per system fee. RHN is roughly equivalent in function to Microsoft's Windows Update which is a free service that Microsoft offers to keep its commercially licensed operating systems up to date.

Given these variations, and the $30 difference in the RHN annual fee, small businesses are prone to choose RedHat Linux. Why do we need an Enterprise class product?

The answer is simple once one understands that each version of RedHat Linux will only be updated for 12 months, and then you will presumably be forced to upgrade versions. As any systems administrator can tell you, this is when problems (lost productivity, down time, broken applications) occur. Recently we have seen 7.3, a first time for a fourth minor revision, and 8.0 both superceded by 9.

Presumably there will be a new release in less than 12 months, I foresee a schedule of updates every 10 months. So the RedHat Enterprise Linux with a 5 year support life cycle, seems like the way to go.

Only one problem. My app doesn't even run on 8.0 yet. No mention of Enterprise at all on the vendor's web site. I hope RedHat doesn't find out the hard way, by loosing Linux market share, that they can't wield the bully pulpit the same way Microsoft does forcing market changes on its customers.

O'Reilly Network: [April 15, 2003] has a complete listing of Linux commands and example usage from agetty to znew.

If you don't use agetty I'm not suprized its usually called by init to set terminal parameters. And znew converts ".Z" zip files to ".gz" zip files of course.

If I start posting more of these straightforward links with only the briefest of comments, it's because I installed "bookmarklets". Which are only kinda working, but that's another story.

This article by Kevin Poulsen at Security Focus caught my interest recently because it is an example of just how important computer security is in places where you might not expect it. For instance, the public power grid.

The article describes challeneges faced in securing the national power grid in today's global political climate. (Electric distribution network is a critical infrastructure resource by any definition I can think of.) This is not news, we've known the systems were vulnerable for about 4 or 5 years now, but it takes on additional urgency in light of the September 11 2001 terrorist attacks. The link will take you to a page where you can read about and request a copy of the 1997 Strategic Assessment report, which was updated in Septemeber of 2001.

This also interested me because one of my clients is a manufacturer of cogeneration systems and inventors of some very cool power related technology. CRM Energy Technologies' web site describes their product "On-Site Combined Heat and Power Systems™", and the technology they have developed, "Energy On Demand™".

So, although yesterday's AdvisorBits design work looked beautiful in Explorer 6, it broke in Netscape 7 and Opera 6. Problem was that when the content div is floated left, you can't set the width on the links div. I imagine the content div is floated so that the links div comes after the content div in the code. This will cause it to break gracefully with links at the bottom of the page in browsers that don't understand css. (Like Netscape on my SGI-O2)

For those of you that don't use a modern VISUAL browser, I apologize in advance. Maybe I could put in a link that only renders in aural browser that says "Go right to the text". I read the latest AlertBox, and I think I know wht he's talkin about. I'm just not sure what to do about this. (And it's more than enough of a discussion for its own post.)

By swaping the order of the divs, and floating the links div right I get much closer to what I want, in fact it was erie, because Opera rendered more or less like I ultimately wanted it to, but Netscape and IE both gave me what I expected. I am aware that if you use a broswer that doesn't understand this that you'll probably get lost.

Or if you resize the browser in such a way that the fixed width of the links div... anyway, the 65% width had to go. By playing with the right margin and padding of the content I was able to get about what I expected in all three browsers. Here's how the CSS ended up:

#content {
margin-right:95px;
padding-right:95px;
padding-bottom:10px;
background:#ccc;
border-right:1px solid #333;

}

#links {
float:right;
width:150px;
background:#ccc;
margin:5em 10px 10px 10px;
padding:10px;
border: 1px solid #630;
}

Remember that I switched the order of the divs in the index.html template, and I really have to figure out a better way around that. It may validate for CSS but its really ugly for accessible. But now it looks like I want it to. I'm pretty sure it will validate again with only the same warnings about inherited colors.

If anyone's been looking (and I know of three... a vast number relatively speaking) over the past week or so, some changes have been happing to the style and to a lesser degree the layout of AdvisorBits. This is not a totally original design. I am still using Movable Type's default templates (mostly) and the stylesheet is taken more directly than you might imagine from the "Stormy" style that is supplied with Movable Type.

The big changes are how posts are selected for display on the main page, and changing the <div> with the id "links" on the right side of the page.

I write about things as I am inspired. Inspiration often comes to me when my clients ask questions or raise issues. Although I am really commmitted to keeping this site fresh, I do not have a firm "I will post something every day, or every week" kind of schedule.

That is one of the reasons I removed the calendar. I have also changed the "<MTEntries>" from the default of showing the last few days as configured through the MT interface; to showing the last three entries without regard for the age of the posts. The code for this is in the "index template" and it looks like:

<MTEntries lastn="3">

I've also used a couple of CSS tricks to make the "links" <DIV> appear more like a navigation area. Previously I though it looked like, well, the right hand side of the page. I have put a border on all four sides of the area, instead of just one dotted line visually separating the primary content from the navigation. I have also used the frequently misunderstood position:relative in order to tie the navigation box visually into the whole page. It still breaks if the user agent viewing window is too narrow. (Your browser doesn't have enough pixels, its not my problem.) Here's the changes I made to the MT Stormy style sheet with regard to <div id="links">:

#links { position:relative; left:-80px; background:#ccc; margin:5em 0 0 0; width:160px; padding:5px; border: 1px solid #630; }

It should be noted that we're still validating.

And one day I know I'll get rid of all the warnings too. As always, your comments are welcome. Next on the list of improvements is an about page, a privacy page, and some new stuff on the navigation area.