ActionScript 2 Tip Of The Day

This info is available elsewhere on the web, but it was hard to find, so maybe reposting it here will make it easier (and if I need it again, I’ll be able to find it myself!).

If you are trying to use BitmapData.draw() to create BitmapData based on some file that you loaded from a remote server, e.g., via loadMovie(), and your output BitmapData is blank/empty/all white space, there is a good chance that you need to force your AS2 code to load the crossdomain.xml file from the remote server via in order for it to work. Without this, Flash decides that it doesn’t have permissions to write the image to a new BitmapData object, even if it’s already happily displaying the loaded image to you on the screen. Makes no sense to me, but this is the workaround.:)

Hope this helps someone else who hasn’t made the move to AS3 yet.

Volumetric Raycasting and Near-Plane Clipping

Just a little note that if you need to prevent near-plane clipping while moving the camera into your volume, there seems to be a simple way to achieve this effect (in OpenGL): simply enable GL_DEPTH_CLAMP while rendering the front and back faces of the bounding volume you are casting from. There may be a better way to do this, but this seems to work and with no noticeable performance loss.

QuickFIX/J and Odd Memory Leaks

This is more a case of posting here to remind myself, but maybe it will help someone out. I just ran into a case where QuickFIX/J seemed to be stacking up endless messages in a LinkedHashMap object (messageQueue) in (discovered using a heap dump and the helpful Memory Analysis Tool from Eclipse) and spent a few hours banging my head on the wall trying to figure out why. After I bothered to read the QFJ code, I understood why, but it’s non-obvious.

Essentially, QFJ’s Session class parses each incoming message, and then attempts to parse any “queued” messages from the aforementioned LinkedHashMap before doing it all again. The contents of the LinkedHashMap (in my case, built up to 500+ megabytes before bringing the JVM to flaming ruin) are only messages that result from a “sequence number too high” error. So if your QFJ application throws, for example, a repeated NPE while handling FIX messages, in certain cases this can trigger a “sequence number too high” problem and will result in FIX messages stacking up in that QFJ-side queue.

I’m not sure if this is really a bug in QFJ or not — I should have checked the QFJ event log sooner, and I might have solved this without noticing the pileup. I suspect that’s why there isn’t a lot of information to be easily found online about the issue – other people just debug their applications correctly.;) That said, it’s non-obvious to me that anything I do in my QFJ application should result in some map inside QFJ’s core classes growing out of control. Hence, noted for myself and anyone else who may care/be curious.:)

FreeSwitch Directory and Lua

I’ve had occasion to play around with FreeSwitch lately and was looking at implementing a directory of extensions on the main menu, and so I set up Brian Snipes’ example Lua directory from the FreeSwitch wiki. I didn’t like the fact that the extension list was hardcoded, so I replaced the names{} table with the following bit of code. It’s ugly, but it’s my first 2-3 hours of messing with Lua. Anyway, it basically makes a system call to “grep” to pull the extensions out of your FS directory XML files using the effective_caller_id_* values which you may or may not have in each listing in the directory. Maybe this will help someone avoid having to reinvent the wheel completely.

Note: this presumes that each entry in the directory lives in its own users_[firstinitial][lastname].xml file. For example, I have users_nsimpson.xml containing the following two lines:

<variable name="effective_caller_id_name" value="Nate Simpson"/>
<variable name="effective_caller_id_number" value="1000"/>

You can hack the following code to match the particulars of your own installation. Also, I think string.gfind() has become string.gmatch() in Lua 5.1, so you may need to tweak that as well.

-- NS: build the names table from grep
directory_path = "/usr/local/freeswitch/conf/directory/default/"

namesearch = io.popen("grep effective_caller_id_ "..directory_path.."user_*.xml")
namelist = namesearch:read("*a")

names = {}

for thisuser, thisname in string.gfind(namelist, "user_(%a+)\.xml:%s+

SIMILE Timeline and XML String Datasources

I’ve recently been playing around with the SIMILE Timeline visualizer for XML data, which is pretty neat. I had one minor little gripe with it, which is that I wanted to be able to use data from an XML string in certain cases where I already was working in the context of an XSL stylesheet instead of hitting the server again just to present the same data in a different XML structure for the timeline. So I downloaded the code, told it NOT to use the bundled code in timeline-bundle.js by editing appropriately in timeline-api.js, and started experimenting with the sources.

What seems to have worked for me is the following modification [I added it just before the line starting: Timeline.DefaultEventSource.prototype.loadXML = function…] to sources.js (pardon the messy formatting here – you can correct the line breaks in the text editor of your choice 🙂 ):

Timeline.DefaultEventSource.prototype.loadXMLText = function(sometext) {
return Try.these(
// For Firefox, etc.
function() { return new DOMParser().parseFromString(sometext, ‘text/xml’); },
// For IE
function() { var xmldom = new ActiveXObject(‘Microsoft.XMLDOM’); xmldom.loadXML(sometext); return xmldom; },
// As a last resort, try loading the document from a data: URL. This is supposed to work in Safari. Thanks to Manos Batsis and his Sarissa library ( for this technique. (NS: – got this from timeline-helper.js in the GWT Timeline build)
function() { var url = “data:text/xml;charset=utf-8,” + encodeURIComponent(sometext); var request = new XMLHttpRequest();“GET”, url, false); request.send(null); return request.responseXML; }

and in your calling script, replacing the line:

Timeline.loadXML(“example1.xml”, function(xml, url) { eventSource.loadXML(xml, url); });

with the following:

eventSource.loadXML(eventSource.loadXMLText(xmlstring,), “”);

Replace “xmlstring” with either a quoted string of XML or a string variable, and edit your path accordingly. Hope it works for you – it seems to be working fine for me!

Silly Tech Tip Of The Week: Linux, DNS, and DHCP

If you are running Linux and you change from a DHCP setup to a static IP address on your local network, and then at some future time your ISP changes your external IP address and your internet slows to a crawl, you might find it useful to know that your resolv.conf file probably contains the old DNS entries set up back when you were using DHCP. It’s a simple matter to change it, but knowing the problem is 99% of this battle. Maybe this will help someone else out there some day who wonders why a Windows box on the same network is chugging along happily but your Linux box is choking. Happy surfing!

MySQL Is Driving Me Insane – GROUPed VIEWs and Multi-Table UPDATEs

I was pretty happy to discover that the latest releases of MySQL (5.0+) allow for creating VIEWs and offer improved subqueries. I’ve been trying to incorporate some of this into my latest little game project, but a few irritations in MySQL are making it a miserable process.

The biggest problem is that the new MySQL VIEWs automatically resort to TEMPTABLE if you throw a GROUP BY into a query. As a result, it’s impossible to create certain types of VIEWs on very large tables, because your logical WHERE restriction on the VIEW behaves as if you issued GROUP BY…HAVING on the underlying query instead of WHERE somerestriction[s]…GROUP BY. If your query would return 10,000 rows (yes, I know that’s only relatively “very large” but I need to keep my query result times in the sub-second range and I only need 32 of those rows) before HAVING is applied, well, that’s what you get with the VIEW. For example:

CREATE VIEW myview AS SELECT foo.ID FROM foo_table foo GROUP BY;

In that little snippet, you’d think that you could “SELECT * FROM myview WHERE foo.ID = 1” and restrict the result set, but the WHERE restriction is applied as a HAVING. This is really, really unfortunate, as it makes the VIEW painfully, unusably slow when you have more than a tiny handful of rows.

The second annoyance is that while MySQL supports multi-table UPDATEs, it behaves in an illogical (to me) fashion when trying to do the following:

UPDATE foo JOIN bar ON somecondition SET foo.somefield = foo.somefield + 1;

The logical behavior seems to me to be that for each “bar”, “somefield” would get incremented by 1. However, in practice, MySQL updates “somefield” once and ignores the rest of the results returned by the “bar” JOIN. It’s almost the same problem discussed here and here, but dumping/reloading the tables seems irrelevant (as does my MySQL version – 5.0.22 currently) and I seem to be bumping up against a restriction briefly mentioned at the bottom of the MySQL “UPDATE Syntax” documentation page – “Currently, you cannot update a table and select from the same table in a subquery.” [Emphasis mine] I’m not the only person to have raised questions about UPDATE’s odd multi-table behavior.

I was hoping to use something like the second to mitigate the problems created by the VIEW shortcomings, but that doesn’t seem to be happening. The best solution I’ve encountered seems to be to use group functions in a subquery as per:

(SELECT SUM(somevalue), id FROM bar WHERE somecondition GROUP BY something) bar_alias
SET foo.somefield = foo.somefield + bar_alias.somevalue

That’s much less elegant and less flexible than using either an UPDATE…JOIN myview or UPDATE…join_query which I’d hoped to be able to do.

Here’s to hoping that the VIEW gets optimized better for the future. It would definitely make my life easier to be able to use GROUP BY in a VIEW without choking up my system. Or maybe “Currently” will become “Long ago” and I can use self-joining table UPDATEs, which is better than nothing.

And if you happen to know any way around either of these that doesn’t involve eliminating the GROUP BY on a VIEW or using a SUM() on the UPDATE, please tell me!

The Life of Nathan, Part 19839

It’s been a couple of weeks since I posted, so just thought I’d let everyone know what I’m up to.

I’ve finally gotten back on the writing roll, pushing 45,000 words on my current writing project – a second novel. It’s a sci-fi novel, a bit cyber-punk maybe, with a lot of action. The basic premise? Three cultures colliding in one future city, and the human body itself the first front in an inevitable war. Overall, quite different from my first story. Have I titled it yet? No, but as soon as I come up with a title I’ll announce it here.

I’m seriously considering trying to publish the second novel officially, and from what I read online, publishing it on my website will make that process more difficult. If you want to read some of it, email me and I’ll send you enough to whet your interest.

My Earth:2025 rewrite is still in progress. I’ve made some minor changes in the code and am still working with a buddy to get a server up for an alpha run of the game. The first time through will be pretty vanilla, but some major gameplay changes definitely possible – as well as extensive community modding, which I think would be a first for this type of game.

Look out for more stories to come in my writing section, and one closet [comedic] drama which might be posted as well.

If you like Earth:2025

If you’re an Earth: 2025 player, you might be interested to know that I’m remaking the game. There have been a number of problems with it that have gone unrepaired despite player complaints, so I’ve always wanted to address them. The idea has been on the back burner for a few years, and I’m finally getting around to doing it.

While I’m starting out with a straight clone, a few potential changes – some with code in place – are:

  • No more “magic” land; the game will be map-based
  • No more private market; there will be a realtime (no 6-8 hour delay) public market instead
  • Alliances will be directly supported in-game, complete with GT-style utilities

Other things are in the works, but always first things first, right? I’ll post updates as I go, so feel free to check in here!


I released a 0.01 version of NateOffice today. The administrative side is still buggy as hell (thank the gods for phpMyAdmin) but the user side is working quite nicely, in my honest opinion. Still a hell of a lot of work to do, but at least maybe some people can start playing with it now.

Update: November 09, 2007: NateOffice has changed quite a lot since that initial release and there are more changes coming up that will hopefully pave the way to something with a nice UI and a 1.0 release in the next few months.

While I’m happy to provide help if I can, please use the forums and bug reporting at for this, as that way I can track the issues separately and deal with them as they come up. Additionally, there is another person now working on this project at times, and he will not notice issues if you post them here. Thanks for your interest!