|
»
Parameter marshalling between iframes + DWR
|
View:
New views
7 Messages
—
Rating Filter:
Alert me
|
 |
Parameter marshalling between iframes + DWR
by matan_a
::
Rate this Message:
I came upon an issue... not with DWR directly but with how the browsers (Firefox + IE at least) marshal object parameters between iframes which makes a nice mess.
When you pass an object as a parameter between a window and an iframe the object is "cloned" i guess and the type information of the object is removed. All the functionality of the object is copied though so you mostly won't notice. For example: On page 1: <html> <head> <title>test</title> <script type="text/javascript"> function test() { var d = new Date(); var s = new String(); var b = new Boolean(); var n = new Number(); alert("Parent Date: " + (d instanceof Date)); alert("Parent String: " + (s instanceof String)); alert("Parent Boolean: " + (b instanceof Boolean)); alert("Parent Number: " + (n instanceof Number)); window.test2.testdate(d); window.test2.teststring(s); window.test2.testboolean(b); window.test2.testnumber(n); } </script> </head> <body> <input type="button" value="Test!" onclick="test()" /> <iframe id="test2" name="test2" src="test2a.html" /> </body> </html> And on page 2: <html> <head> <title>test2</title> <script type="text/javascript" src="/includes/dojo/dojo/dojo.js" djConfig="isDebug: false, parseOnLoad: false, baseScriptUri: '/includes/dojo'"></script> <script type="text/javascript"> function testdate(d) { alert("IFrame Date: " + (d instanceof Date)); }; function testboolean(b) { alert("IFrame Boolean: " + (b instanceof Boolean)); }; function testnumber(n) { alert("IFrame Number: " + (n instanceof Number)); }; function teststring(s) { alert("IFrame String: " + (s instanceof String)); }; </script> </head> <body> </body> </html> All the results of the page 2 will be false because the object loses it's type definition during marshalling. This matters to DWR because the serializing done in the engine.js relies on instanceof to correctly create data - which causes errors because the type information is gone. Obviously this only will be noticed if you are using DWR inside the iframe with data passed in from another window: From engine.js: dwr.engine._serializeAll = function(batch, referto, data, name) { if (data == null) { batch.map[name] = "null:null"; return; } switch (typeof data) { case "boolean": batch.map[name] = "boolean:" + data; break; case "number": batch.map[name] = "number:" + data; break; case "string": batch.map[name] = "string:" + encodeURIComponent(data); break; case "object": if (data instanceof String) batch.map[name] = "String:" + encodeURIComponent(data); else if (data instanceof Boolean) batch.map[name] = "Boolean:" + data; else if (data instanceof Number) batch.map[name] = "Number:" + data; else if (data instanceof Date) batch.map[name] = "Date:" + data.getTime(); else if (data && data.join) batch.map[name] = dwr.engine._serializeArray(batch, referto, data, name); else batch.map[name] = dwr.engine._serializeObject(batch, referto, data, name); break; case "function": // We just ignore functions. break; default: dwr.engine._handleWarning(null, { name:"dwr.engine.unexpectedType", message:"Unexpected type: " + typeof data + ", attempting default converter." }); batch.map[name] = "default:" + data; break; } }; If this case for a "marshalled" date, it would still be typeof "object", but not instanceof Date anymore and would use the regular _serializeObject. I personally have avoided this fix by reinstating the correct objects before calling DWR but this can be a pain and is error-prone. Is there any chance for a fix inside DWR itself? For your convenience, i attached the example as html files so you can see it happen.test.zip |
|
|
Re: Parameter marshalling between iframes + DWR
by matan_a
::
Rate this Message:
Sorry, just wanted to say that the dojo script reference is irrelevant to the example :) forgot to remove it.
|
|
|
RE: Parameter marshalling between iframes + DWR
by mikewse
::
Rate this Message:
Hi matan,
[sorry about the delay, going through old mails...] > I came upon an issue... not with DWR directly but with how > the browsers > (Firefox + IE at least) marshal object parameters between > iframes which > makes a nice mess. > > When you pass an object as a parameter between a window and > an iframe the > object is "cloned" i guess and the type information of the object is > removed. All the functionality of the object is copied > though so you mostly > won't notice. For example: Yes, instanceof and multiple frames usually means problems (but it actually isn't about cloning, it's about different prototype objects on types). Joe: I think we decided to remove all use of instanceof some time ago. Should I go in and fix engine.js for 2.0.4 ? Best regards Mike --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscribe@... For additional commands, e-mail: users-help@... |
|
|
Re: Parameter marshalling between iframes + DWR
by Joe Walker-3
::
Rate this Message:
Yes please, Mike. Thanks, Joe. On Wed, May 14, 2008 at 4:58 PM, Mike Wilson <mikewse@...> wrote: Hi matan, |
|
|
RE: Parameter marshalling between iframes + DWR
by mikewse
::
Rate this Message:
Ok, now I've checked in updated code for correctly
detecting native types across frames.
To get this working across all browsers (available to me:
IE6, IE7, FF2, Safari 2 & 3, Opera 9) I had to use the classic
Object.prototype.toString.call() trick. This decreases type detection
performance to 17usec from previous 11usec (using instanceof) on my mid-range
PC.
In the great whole of serializing data this is probably not
a big deal, but we could improve this performance by f ex caching the type
detection on each native class's constructor function. That would bring type
detection cost down to 8usec (ie better than before) but would mean adding a
property (something like "$dwrclass" or similar) on each visited native
class on the global object. Note that this wouldn't imply any property
pollution on user objects as the property would be added to the
constructor function and not to the prototype object.
Any comments or opinions about this?
Joe: I've only checked this in for the 2.x branch
currently. Should I update HEAD as well or will you do it
yourself?
Best regards
Mike
|
|
|
Re: Parameter marshalling between iframes + DWR
by Joe Walker-3
::
Rate this Message:
On Sun, Jun 29, 2008 at 11:28 AM, Mike Wilson <mikewse@...> wrote:
My gut reaction is that this could still end up breaking things. I think the general rule for libraries is to polute close to nothing - which is what this is all about: http://www.openajax.org/member/wiki/Registry_Candidates
Yes please (IIRC, you did already?). Joe. |
|
|
RE: Parameter marshalling between iframes + DWR
by mikewse
::
Rate this Message:
That's fine, we'll skip that then.
No, I only checked in 2.x branch so there's still
instanceof in HEAD's engine.js?
(But I'll be checking in the fixed version the next few
minutes.)
Best regards
Mike
|
| Free embeddable forum powered by Nabble | Forum Help |
