The underlying class is not using deferred binding, therefore your replace-with is never considered. In order for deferred binding to work, you must use GWT.create(); What I would suggest you do is do your own request builder implementation. There are many ways you can do this, but to do defferred binding you have to call GWT.create somewhere along the way and it must match or be a sub class of the class listed in when-type-is.
On Apr 16, 12:41 pm, snctln <[email protected]> wrote: > [Sorry in advance for the lengthy post, I just posted this question > over on stack overflow and copy/pasted the question here for more > visibilty, so this is formatted with markup and all links referenced > are at the bottom of the post] > > I developed a web app using GWT about 2 years ago, since then the > application has evolved. In its current state it relies on fetching a > single XML file and parsing the information from it. Overall this > works great. A requirement of this app is that it needs to be able to > be ran from the filesystem (file:///..) as well as the traditional > model of running from a webserver (http://...) > > Fetching this file from a webserver works exactly as expected using a > [RequestBuilder][1] object. When running the app from the filesystem > Firefox, Opera, Safari, and Chrome all behave as expected. When > running the app from the filesystem using IE7 or IE8 the > [RequestBuilder.send()][2] call fails, the information about the error > suggests that there is a problem accessing the file due to violating > the [same origin policy][3]. > The app worked as expected in IE6 but not in IE7 or IE8. > > So I looked at the source code of [RequestBuilder.java][4] and saw > that the actual request was being executed with an XMLHttpRequest GWT > object. So I looked at the source code for [XMLHttpRequest.java][5] > and found out some information. > > Here is the code (starts at line 83 in XMLHttpRequest.java) > > public static native XMLHttpRequest create() /*-{ > if ($wnd.XMLHttpRequest) { > return new XMLHttpRequest(); > } else { > try { > return new ActiveXObject('MSXML2.XMLHTTP.3.0'); > } catch (e) { > return new ActiveXObject("Microsoft.XMLHTTP"); > } > } > }-*/; > > So basically if an XMLHttpRequest cannot be created (like in IE6 > because it is not available) an ActiveXObject is used instead. > > I read up a little bit more on the IE implementation of > XMLHttpRequest, and it appears that it is only supported for > interacting with files on a webserver. > > I found a setting in IE8 (Tools->Internet Options->Advanced->Security->Enable > native XMLHTTP support), when I uncheck this box my app > > works. I assume this is because I am more of less telling IE to not > use their implementation of XmlHttpRequest, so GWT just uses an > ActiveXObject because it doesn't think the native XmlHttpRequest is > available. > > This fixes the problem, but is hardly a long term solution. > > I can currently catch a failed send request and verify that it was > trying to fetch the XML file from the filesystem using normal GWT. > What I would like to do in this case is catch the IE7 and IE8 case and > have them use a ActiveXObject instead of a native XmlHttpRequest > object. > > There was a posting on the GWT google group that had a supposed > solution for this problem ([link][6]). Looking at it I can tell that > it was created for an older version of GWT. I am using the latest > release and think that this is more or less what I would like to do > (use [GWT deferred binding][7] to detect a specific browser type and > run my own implementation of XMLHttpRequest.java in place of the built > in GWT implementation). > > Here is the code that I am trying to use > > package com.mycompany.myapp.client; > > import com.google.gwt.xhr.client.XMLHttpRequest; > > public class XMLHttpRequestIE7or8 extends XMLHttpRequest > { > // commented out the "override" so that eclipse and the ant > build script don't throw errors > //@Override > public static native XMLHttpRequest create() > /*-{ > try > { > return new ActiveXObject('MSXML2.XMLHTTP.3.0'); > } > catch (e) > { > return new ActiveXObject("Microsoft.XMLHTTP"); > } > }-*/; > > // have an empty protected constructor so the ant build script > doesn't throw errors > // the actual XMLHttpRequest constructor is empty as well so > this shouldn't cause any problems > protected XMLHttpRequestIE7or8() > { > } > }; > > And here are the lines that I added to my module xml > > <replace-with > class="com.mycompany.myapp.client.XMLHttpRequestIE7or8"> > <when-type-is class="com.google.gwt.xhr.client.XMLHttpRequest"/ > > <any> > <when-property-is name="user.agent" value="ie7" /> > <when-property-is name="user.agent" value="ie8" /> > </any> > </replace-with> > > From what I can tell this should work, but my code never runs. > > Does anyone have any idea of what I am doing wrong? > > Should I not do this via deferred binding and just use native > javascript when I catch the fail case instead? > > Is there a different way of approaching this problem that I have not > mentioned? > > All replies are welcome. > > [1]:http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/g... > [2]:http://google-web-toolkit.googlecode.com/svn/javadoc/2.0/com/google/g... > [3]:http://en.wikipedia.org/wiki/Same_origin_policy > [4]:http://code.google.com/p/google-web-toolkit/source/browse/releases/2.... > [5]:http://code.google.com/p/google-web-toolkit/source/browse/releases/2.... > [6]:http://groups.google.com/group/google-web-toolkit/browse_thread/threa... > [7]:http://code.google.com/webtoolkit/doc/latest/DevGuideCodingBasicsDefe... > > -- > You received this message because you are subscribed to the Google Groups > "Google Web Toolkit" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group > athttp://groups.google.com/group/google-web-toolkit?hl=en. -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. 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