xpath - Dave's Blog


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2015 Mar 18, 10:48
Xpath in #EdgeHTML using CSS selectors and WGX (Wicked Good XPath) http://blogs.msdn.com/b/ie/archive/2015/03/19/improving-interoperability-with-dom-l3-xpath.aspx … The tech here is amazing. #ICodeReviewedThat

Client Side Cross Domain Data YQL Hack

2012 Feb 27, 2:28

One of the more limiting issues of writing client side script in the browser is the same origin limitations of XMLHttpRequest. The latest version of all browsers support a subset of CORS to allow servers to opt-in particular resources for cross-domain access. Since IE8 there's XDomainRequest and in all other browsers (including IE10) there's XHR L2's cross-origin request features. But the vast majority of resources out on the web do not opt-in using CORS headers and so client side only web apps like a podcast player or a feed reader aren't doable.

One hack-y way around this I've found is to use YQL as a CORS proxy. YQL applies the CORS header to all its responses and among its features it allows a caller to request an arbitrary XML, HTML, or JSON resource. So my network helper script first attempts to access a URI directly using XDomainRequest if that exists and XMLHttpRequest otherwise. If that fails it then tries to use XDR or XHR to access the URI via YQL. I wrap my URIs in the following manner, where type is either "html", "xml", or "json":

        yqlRequest = function(uri, method, type, onComplete, onError) {
var yqlUri = "http://query.yahooapis.com/v1/public/yql?q=" +
encodeURIComponent("SELECT * FROM " + type + ' where url="' + encodeURIComponent(uri) + '"');

if (type == "html") {
yqlUri += encodeURIComponent(" and xpath='/*'");
else if (type == "json") {
yqlUri += "&callback=&format=json";

This also means I can get JSON data itself without having to go through JSONP.
PermalinkCommentsxhr javascript yql client-side technical yahoo xdr cors

JSONPath - XPath for JSON

2011 Apr 20, 2:26PermalinkCommentsjson xpath javascript library technical

Powershell to test your XPath

2011 Apr 14, 5:11This page and esp. the final comment on the page were very helpful with describing how to parse XML in PowerShell.PermalinkCommentspowershell xml xpath technical programming

Web Q&A: XPath, XML Notepad, Data Islands, Case Sensitivity, XSL, and More -- MSDN Magazine, September 2001

2008 Feb 7, 2:36To summ up the last Q&A, the one I was interested in: "Is there any way to escape the characters " and ' in an XPath expression...". And their answer is no. Lame. I thought XPath folk would have defined this.PermalinkCommentsmicrosoft msdn xpath xml article

XSLT Standard Library

2007 Sep 27, 12:01Another open effort to produce an XSLT library that does some standard things you might want like string manipulation, URI combining, etc etcPermalinkCommentsxsl xslt reference library xml xpath proramming api


2007 Sep 26, 11:57Free XSLT Extension libraries to support things like date/time conversions, string manipulation, etc.PermalinkCommentsxslt xsl api xpath xml library extension programming free development

XPointer Framework - IE7 XML Source View Upgrade Part 3

2007 May 17, 5:16Previously I created some resource tools and then I used them to overwrite msxml3's XML source view. In this update I've added support for the XPointer Framework.

This time around I've started to add support for the XPointer Framework to my XML source view and I've added installation instructions. The framework consists of a series of pointer segments each of which has a scheme name followed by data in parenthesis. For example 'scheme1(data1)scheme2(data2)scheme3(data3)'. A pointer segment resolves to a portion of the XML document based on the data and the scheme name. The whole pointer resolves to the first segment that successfully resolves. That is, from the example, if scheme1 resolves to nothing and scheme2 resolves to something then that's used and scheme3 is ignored. In addition to the framework I've added support for the xmlns scheme which binds namespace prefixes to a namespace URI and the element scheme which is a simple way to resolve to particular elements in an XML. I also have limited support for the xpointer scheme the content of which is resolved as an XPath with some extra functions (which I don't support -- hence the limited). I've also thrown in schemes for the two SelectionLanguage values supported by msxml3.

Next time I might try to support the xpointer functions that aren't in xpath using msxml script. But I think I'm losing steam on this project... we'll see.PermalinkCommentsresource technical xml xpointer res xpath xslt

New XSLT - IE7 XML Source View Upgrade Part 2

2007 May 11, 8:55Last time, I had written some resource tools to allow me to view and modify Windows module resources in my ultimate and noble quest to implement the XML content-type fragment in IE7. Using the resource tools I found that MSXML3.DLL isn't signed and that I can replace the XSLT embedded resource with my own, which is great news and means I could continue in my endevour. In the following I discuss how I came up with this replacement for IE7's XML source view.

At first I thought I could just modify the existing XSLT but it turns out that it isn't exactly an XSLT, rather its an IE5 XSL. I tried using the XSL to XSLT converter linked to on MSDN, however the resulting document still requires manual modification. But I didn't want to muck about in their weird language and I figured I could write my own XSLT faster than I could figure out how theirs worked.

I began work on the new XSLT and found it relatively easy to produce. First I got indenting working with all the XML nodes represented appropriately and different CSS classes attached to them to make it easy to do syntax highlighting. Next I added in some javascript to allow for closing and opening of elements. At this point my XSLT had the same features as the original XSL.

Next was the XML mimetype fragment which uses XPointer, a framework around various different schemes for naming parts of an XML document. I focused on the XPointer scheme which is an extended version of XPath. So I named my first task as getting XPaths working. Thankfully javascript running in the HTML document produced by running my XSLT on an XML document has access to the original XML document object via the document.XMLDocument property. From this this I can execute XPaths, however there's no builtin way to map from the XML nodes selected by the XPath to the HTML elements that I produced to represent them. So I created a recursive javascript function and XSLT named-template that both produce the same unique strings based on an XML node's position in the document. For instance 'a3-e2-e' is the name produced for the 3rd attribute of the second element of the root element of the XML document. When producing the HTML for an XML node, I add an 'id' attribute to the HTML with the unique string of the XML node. Then in javascript when I execute an XPath I can discover the unique string of each node in the selected set and map each of them to their corresponding positions in the HTML.

With the hard part out of the way I changed the onload to get the fragment of the URI of the current document, interpret it as an XPath and highlight and navigate to the selected nodes. I also added an interactive floating bar from which you can enter your own XPaths and do the same. On a related note, I found that when accessing XML files via the file URI scheme the fragment is stripped off and not available to the javascript.

The next steps are of course to actually implement XPointer framework parsing as well as the limited number of schemes that the XPointer framework specifies.PermalinkCommentsxml xpointer msxml res xpath xslt resource ie7 technical browser ie xsl

XML Pointer Language (XPointer)

2007 May 10, 12:17The XPointer specification describing the fragment used with text/xml documents.PermalinkCommentsw3c xml xpath xpointer reference uri fragment

XPointer Framework

2007 Feb 22, 10:44The standard for URI fragments for identifying portions of an XML document. I've been looking for this...PermalinkCommentsxml xpointer w3c specification standards xpath uri fragment

XML Path Language (XPath)

2006 Nov 13, 2:12Official docs on the XPath language. XPath allows you to describe pieces of an XML document by navigating and filtering the XML heirarchy via a string that looks like a file system path.PermalinkCommentsxml xpath w3c reference development programming internet quickreference
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