coding page 2 - Dave's Blog



2012 Jun 22, 9:19

jQuery plugin that blindly removes lines with errors and recompiles until it works  

PermalinkCommentstechnical humor javascript programming coding jquery

HTTP Compression Documentation Reference

2012 Jun 13, 3:08
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.

PermalinkCommentscompress compression deflate gzip http http-header technical zlib

URI Percent Encoding Ignorance Level 2 - There is no Unencoded URI

2012 Feb 20, 4:00

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

Getting into the more subtle levels of URI percent-encoding ignorance, folks try to apply their knowledge of percent-encoding to URIs as a whole producing the concepts escaped URIs and unescaped URIs. However there are no such things - URIs themselves aren't percent-encoded or decoded but rather contain characters that are percent-encoded or decoded. Applying percent-encoding or decoding to a URI as a whole produces a new and non-equivalent URI.

Instead of lingering on the incorrect concepts we'll just cover the correct ones: there's raw unencoded data, non-normal form URIs and normal form URIs. For example:

  3. "http", "", "the?path", "query"

In the above (A) is not an 'encoded URI' but rather a non-normal form URI. The characters of 'the' and 'path' are percent-encoded but as unreserved characters specific in the RFC should not be encoded. In the normal form of the URI (B) the characters are decoded. But (B) is not a 'decoded URI' -- it still has an encoded '?' in it because that's a reserved character which by the RFC holds different meaning when appearing decoded versus encoded. Specifically in this case, it appears encoded which means it is data -- a literal '?' that appears as part of the path segment. This is as opposed to the decoded '?' that appears in the URI which is not part of the path but rather the delimiter to the query.

Usually when developers talk about decoding the URI what they really want is the raw data from the URI. The raw decoded data is (C) above. The only thing to note beyond what's covered already is that to obtain the decoded data one must parse the URI before percent decoding all percent-encoded octets.

Of course the exception here is when a URI is the raw data. In this case you must percent-encode the URI to have it appear in another URI. More on percent-encoding while constructing URIs later.

PermalinkCommentsurl encoding uri technical percent-encoding

URI Percent-Encoding Ignorance Level 1 - Purpose

2012 Feb 15, 4:00

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:

  2. 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:

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".
PermalinkCommentsencoding uri technical ietf percent-encoding

URI Percent Encoding Ignorance Level 0 - Existence

2012 Feb 10, 4:00

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.

PermalinkCommentsencoding uri technical ietf percent-encoding ipv6

Coding in Marble - Rico Mariani's Performance Tidbits - Site Home - MSDN Blogs

2012 Feb 6, 8:47

In short: excessive use of promises leads to a ton of short lived objects and resulting poorer pref.

PermalinkCommentsperf technical javascript promise async

draft-liman-tld-names-06 - Top Level Domain Name Specification

2011 Dec 4, 3:00

“The syntax for allowed Top-Level Domain (TLD) labels in the Domain Name System (DNS) is not clearly applicable to the encoding of Internationalised Domain Names (IDNs) as TLDs. This document provides a concise specification of TLD label syntax based on existing syntax documentation, extended minimally to accommodate IDNs.” Still irritated about arbitrary TLDs.

PermalinkCommentstechnical syntax dns tld idn

Indicating Character Encoding and Language for HTTP Header Field Parameters

2011 Nov 24, 7:45

From the document: ‘Appendix B. Implementation Report: The encoding defined in this document currently is used for two different HTTP header fields: “Content-Disposition”, defined in [RFC6266], and “Link”, defined in [RFC5988]. As the encoding is a profile/clarification of the one defined in [RFC2231] in 1997, many user agents already supported it for use in “Content-Disposition” when [RFC5987] got published.

Since the publication of [RFC5987], two more popular desktop user agents have added support for this encoding; see
   NET/http/content-disposition-tests#encoding-2231-char for details. At this time, only one major desktop user agent (Safari) does not support it.

Note that the implementation in Internet Explorer 9 does not support the ISO-8859-1 encoding; this document revision acknowledges that UTF-8 is sufficient for expressing all code points, and removes the requirement to support ISO-8859-1.’

Yay for UTF-8!

PermalinkCommentstechnical http http-headers ie9 internationalization utf-8 encoding

Using Progress Indicators in Windows PowerShell

2011 Jul 27, 10:33The write-progress command in powershell allows scripts to express their progress in terms of percent or time left and powershell displays this in a friendly manner at the top of my window. Surprisingly, not hooked up to the Shell's TaskbarItemInfo's progress.PermalinkCommentstechnical powershell progress coding shell

Completion of IANA Selection of IDNA Prefix

2010 Dec 8, 6:44Description of how they picked 'xn--' as the ACE prefix for IDN. Shockingly elaborate =)PermalinkCommentsidn technical ace encoding unicode rfc ietf

RFC 6068 - The 'mailto' URI Scheme

2010 Oct 5, 2:54The mailto URI scheme finally gets its own RFC.PermalinkCommentsmailto uri url mail email technical rfc reference encoding

Peer-to-peer tech now powers Wikipedia's videos

2010 Sep 27, 3:15This is awesome and similar to something I got a cube for. Wikipedia runs its videos through a service that sets up torrents for arbitrary URLs. So awesome! Now if only this were built into the user agent rather than requiring hardcoding the sites to use it...PermalinkCommentstechnical p2p wikipedia network networking torrent web

RFC 5987 - Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters

2010 Aug 13, 11:47Other characters sets for HTTP headers: "By default, message header field parameters in Hypertext Transfer Protocol (HTTP) messages cannot carry characters outside the ISO-8859-1 character set. RFC 2231 defines an encoding mechanism for use in Multipurpose Internet Mail Extensions (MIME) headers. This document specifies an encoding suitable for use in HTTP header fields that is compatible with a profile of the encoding defined in RFC 2231."PermalinkCommentsrfc language localization charset http technical reference http-header

Code Standards | Isobar

2010 May 2, 3:14"This document contains normative guidelines for web applications built by the Interface Development practice of Isobar North America (previously Molecular)." Glad to see coding styles and best practices for HTML, CSS, JS, associated HTTP headers etc etc etcPermalinkCommentscode css html html5 javascript web browser programming development technical via:kris.kowal

Riviera Blog :: QTQR

2010 Apr 12, 10:44QR code degenerator allows you to mess with some pixels of a QR code or insert pictures without messing up the encoding.
PermalinkCommentsqrcode qr technical

Encode-O-Matic: Guess Encoding

2010 Apr 4, 2:02

I've just updated Encode-O-Matic with a Guess Input Encoding feature. When you start Encode-O-Matic or when you use the 'Guess Input Encoding' menu item from the 'Tools' menu, Encode-O-Matic will try out various combinations of encodings and guess at which set seem to apply to your input. For instance given the following text, Encode-O-Matic will correctly guess that it is percent encoded, base64 encoded, deflate compressed text:

It should work fairly well for simple things but I did pick 'Guess' for the name of the feature to intentionally lower expectations. It doesn't currently apply to character encodings but that may be something to consider in the future.PermalinkCommentstechnical encodeomatic tool encoding

Getting started with Google Calendar Sync - Google Calendar Help

2010 Mar 21, 3:22Google Calendar Sync is an Outlook plugin that syncs your Google and Outlook calendars (you get to pick 1way and direction or 2way sync'ing). This almost looks like what I want but perhaps my feature requests are too obscure for someone to have already implemented them:
Events marked personal added on my Outlook calendar should get full 2-way sync'ing with my Google calendar.
All other events added on my Outlook calendar should be assumed to have private company information and should get 1-way sync'ing with just the time and location - no attendees or subject or desceiption.
All events added on my Google calendar should get full 2-way sync'ing with Outlook and there should be marked personal.

I doubt I'm going to find a pre-made app to do this so I guess I should get coding. Otoh, if they ever bring the updated Android OS that has Exchange support to my G1 maybe none of this would be necessary...PermalinkCommentsgoogle calendar outlook microsoft tool free technical

Encode-O-Matic Update: Compression, Hex View, Quick Show Output

2010 Mar 9, 9:08

I've just put up an update for Encode-O-Matic with the following improvements:

PermalinkCommentstechnical encodeomatic project

No, you can’t do that with H.264 « Digital Diary of Ben Schwartz

2010 Feb 4, 2:01On the crappy licensing of the H.264 and MPEG codecs in popular video encoding software.PermalinkCommentsvideo encoding codec patent legal law apple microsoft theora h.264 technical

Official Google Blog: Unicode nearing 50% of the web

2010 Jan 28, 4:20Graph of encodings used by documents on the web. Unicode based encodings are thankfully on the rise.PermalinkCommentsunicode encoding web internationalization localization utf8 text html technical
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