age page 30 - Dave's Blog

There's a lot of name reuse in HTTP compression so I've made the following to help myself keep it straight.

HTTP Content Coding Token	gzip	deflate	compress
	An encoding format produced by the file compression program "gzip" (GNU zip)	The "zlib" format as described in RFC 1950.	The encoding format produced by the common UNIX file compression program "compress".
Data Format	GZIP file format	ZLIB Compressed Data Format	The compress program's file format
Compression Method	Deflate compression method		LZW
	Deflate consists of LZ77 and Huffman coding

Compress doesn't seem to be supported by popular current browsers, possibly due to its past with patents.

Deflate isn't done correctly all the time. Some servers would send the deflate data format instead of the zlib data format and at least some versions of Internet Explorer expect deflate data format instead of zlib data format.

Use of my old Hotmail account has really snuck up on me as I end up caring more and more about all of the services with which it is associated. The last straw is Windows 8 login, but previous straws include Xbox, Zune, SkyDrive, and my Windows 7 Phone. I like the features and sync'ing associated with the Windows Live ID, but I don't like my old, spam filled, hotmail email address on the Live ID account.

A coworker told me about creating a Live ID from a custom domain, which sounded like just the ticket for me. Following the instructions above I was able to create a new deletethis.net Live ID but the next step of actually using this new Live ID was much more difficult. My first hope was there would be some way to link my new and old Live IDs so as to make them interchangeable. As it turns out there is a way to link Live IDs but all that does is make it easy to switch between accounts on Live Mail, SkyDrive and some other webpages.

Instead one must change over each service or start over depending on the service:

Xbox

In the Xbox 360 system menu you can change the Live ID associated with your gamertag. This worked fine for me and I got an email telling me about the transfer of my Microsoft Points.

Zune

There's no way to do this for the Zune specifically, however changing over your Xbox account also transfers over all your Zune purchased content. I don't have a Zune Pass so I can't confirm that, but all of my previously purchased television shows transferred over successfully.

Windows 7 Phone

To change the main Live ID associated with your phone, reset your phone to factory default and start over. All purchased applications are lost. Had I purchased any applications I would have been pissed, but instead I was just irritated that I had to reset my phone.

Mail

I don't use my Hotmail account for anything and it only sits and collects spam. Accordingly I didn't attempt switching this over.

SkyDrive

I didn't have much in my SkyDrive account. I downloaded all files as a zip and then manually uploaded them to the new account.

According to MSDN the proper way to permanently add a path to your system's PATH environment variable is by modifying a registry value. Accordingly this is easily represented in a PowerShell script that first checks if the path provided is already there and otherwise appends it:

param([Parameter(Mandatory = $true)] [string] $Path);
$FullPathOriginal = (gp "HKLM:\System\CurrentControlSet\Control\Session Manager\Environment").Path;
if (!($FullPathOriginal.split(";") | ?{ $_ -like $Path })) {
    sp "HKLM:\System\CurrentControlSet\Control\Session Manager\Environment" -name Path -value ($FullPathOriginal + ";" +
 $Path);
}

I'm done playing Fez. The style is atmospheric retro nastalgia and on the surface the gameplay is standard 2D platformer with one interesting Flatland style game mechanic but dig deeper to find Myst style puzzles. Despite the following I thoroughly enjoyed the game and would recommend it to anyone intrigued by the previous. Five eighths through the game I ran into one of the game's infamous Fez save game breaking issues, but I enjoyed the game enough that I started over before any patches were released and had no further issues.

While playing the game I created some tools to help keep track of my Fez notes (spoilers) including a Pixelated Image Creator that makes it easy to generate data URIs for large, black and white pixelated images, and (spoilers) a Fez Transliteration Tool to help me translate the in-game writing system.

Elaborating on a previous brief post on the topic of Web Worker initialization race conditions, there's two important points to avoid a race condition when setting up a Worker:

1. The parent starts the communication posting to the worker.
2. The worker sets up its message handler in its first synchronous block of execution.

For example the following has no race becaues the spec guarentees that messages posted to a worker during its first synchronous block of execution will be queued and handled after that block. So the worker gets a chance to setup its onmessage handler. No race:

'parent.js':
   var worker = new Worker();
   worker.postMessage("initialize");

'worker.js':
   onmessage = function(e) {
      // ...
   }

The following has a race because there's no guarentee that the parent's onmessage handler is setup before the worker executes postMessage. Race (violates 1):

'parent.js':
   var worker = new Worker();
   worker.onmessage = function(e) {
      // ...
   };

'worker.js':
   postMessage("initialize");

The following has a race because the worker has no onmessage handler set in its first synchronous execution block and so the parent's postMessage may be sent before the worker sets its onmessage handler. Race (violates 2):

'parent.js':
   var worker = new Worker();
   worker.postMessage("initialize");

'worker.js':
   setTimeout(
      function() {
         onmessage = function(e) {
            // ...
         }
      },
      0);

As a professional URI aficionado I deal with various levels of ignorance on URI percent-encoding (aka URI encoding, or URL escaping).

Worse than the lame blog comments hating on percent-encoding is the shipping code which can do actual damage. In one very large project I won't name, I've fixed code that decodes all percent-encoded octets in a URI in order to get rid of pesky percents before calling ShellExecute. An unnamed developer with similar intent but clearly much craftier did the same thing in a loop until the string's length stopped changing. As it turns out percent-encoding serves a purpose and can't just be removed arbitrarily.

Percent-encoding exists so that one can represent data in a URI that would otherwise not be allowed or would be interpretted as a delimiter instead of data. For example, the space character (U+0020) is not allowed in a URI and so must be percent-encoded in order to appear in a URI:

1. http://example.com/the%20path/
2. http://example.com/the path/

In the above the first is a valid URI while the second is not valid since a space appears directly in the URI. Depending on the context and the code through which the wannabe URI is run one may get unexpected failure.

For an additional example, the question mark delimits the path from the query. If one wanted the question mark to appear as part of the path rather than delimit the path from the query, it must be percent-encoded:

1. http://example.com/foo%3Fbar
2. http://example.com/foo?bar

In the second, the question mark appears plainly and so delimits the path "/foo" from the query "bar". And in the first, the querstion mark is percent-encoded and so the path is "/foo%3Fbar".

As a professional URI aficionado I deal with various levels of ignorance on URI percent-encoding (aka URI encoding, or URL escaping). The basest ignorance is with respect to the mere existence of percent-encoding. Percents in URIs are special: they always represent the start of a percent-encoded octet. That is to say, a percent is always followed by two hex digits that represents a value between 0 and 255 and doesn't show up in a URI otherwise.

The IPv6 textual syntax for scoped addresses uses the '%' to delimit the zone ID from the rest of the address. When it came time to define how to represent scoped IPv6 addresses in URIs there were two camps: Folks who wanted to use the IPv6 format as is in the URI, and those who wanted to encode or replace the '%' with a different character. The resulting thread was more lively than what shows up on the IETF URI discussion mailing list. Ultimately we went with a percent-encoded '%' which means the percent maintains its special status and singular purpose.