Ah, very good point, Jürgen.
I think the best, and certainly the most compatible, solution would be to
combine:
1) JSONP or any other executable JavaScript format to handle the normal
case.
2) A long timer to handle server failure.
This way you don't have to worry about browser support for
onload/onerror/etc. It will work in any browser that the Maps API supports.
It would even work in ten-year-old browsers! :-)
There's only one semi-modern browser that this would fail in: Safari 2.0.0
had a bug where dynamic script elements did not work at all. This was fixed
in either 2.0.1 or 2.0.2, I'm not sure which.
The Maps API docs claim that the API works in Safari 2.0+. This can't
possibly be right, though, since the Maps API uses dynamic script elements
to download various components, so it will fail in 2.0.0 (and possibly
2.0.1). Therefore I wouldn't worry about the Safari 2.0.0 bug.
-Mike
> From: Jürgen
>
> Michael, I partly agree with you.
> You are right that you don't need a timer or worry about
> event handling when using a callback function. However that's
> only going to work, if nothing goes wrong on the server end
> and the JSON is delivered correctly and in time.
>
> The reason I was using a timer was because in some
> application it might be critical to dectect if the data
> doesn't arrive correctly or in time. Just think about an
> interval server error (error 500) or the site being down at
> all. In this case your callback function is never called and
> you just wait forever. Not so good if you depend on it.
>
> I see two possible solution:
> a) a timer and
> b) event handling with onreadystatechange/onload/onerror.
>
> bratcliff said:
> > It can be done with event handlers. For Internet Explorer, use
> > "onreadystatechange". For Firefox & others, use "onload" /
> "onerror".
>
> What I am really looking for is a solution that will work for
> all browsers for which GBrowserIsCompatible() is true. Does
> anyone happen to know if I can rely on using
> onreadystatechange for IE and onload/ onerror for FF and *all* others?
>
> Jürgen
>
>
> On 25 Okt., 21:17, "Michael Geary" <[EMAIL PROTECTED]> wrote:
> > The "{lat=xxx, lon=xxx}" must a typo? That is neither JSON
> nor JavaScript.
> >
> > Proper JSON would look like this (the whitespace is optional):
> >
> > { "lat": 40.0, "lng": -120.0 }
> >
> > BTW, the quotes on the property names are required for correct JSON
> > format, although they don't matter if you're just
> generating executable JavaScript.
> >
> > By adding the variable assignment, you've changed the response from
> > JSON to executable JavaScript code.
> >
> > However, that's not a complete solution. How do you know when your
> > script has loaded? You don't get notified that a variable
> has been assigned into.
> >
> > That's why JSONP uses a callback, not a variable assignment. If the
> > server response is:
> >
> > mycallback({ "lat": 40.0, "lng": -120.0 })
> >
> > Then you *know* when it's loaded, because your "mycallback"
> function
> > is called at that time.
> >
> > Now you don't have to use a timer (BAD idea!). You don't
> have to worry
> > about readystatechange. You don't have to do any of that.
> You simply
> > have a function in your JavaScript code that *automatically* gets
> > called at exactly the right moment.
> >
> > As I mentioned in my other message, the customary way to do
> this is to
> > provide a callback function name in the URL, such as:
> >
> > http://example.com/myjsonservice?foo=bar&abc=xyz&callback=callme
> >
> > Then the server would generate:
> >
> > callme({ "lat": 40.0, "lng": -120.0 })
> >
> > This places control of the actual function name in the client code.
> >
> > You don't *have* to do that; you can have a hard coded callback
> > function name if you want. But the conventional JSONP
> approach used by
> > many sites lets the client specify the callback name. Most
> JavaScript
> > libraries such as jQuery now have built-in support for JSONP with a
> > callback - it's really the way to go.
> >
> > -Mike
> >
> >
> >
> > > From: Neil.Young
> >
> > > Exactly. The "straight" JSON, delivered until now by my server,
> > > didn't work the very first attempt. Reason: I was missing the
> > > assignment statement, so the plain JSON object "{lat=xxx,
> lon=xxx}"
> > > had to be delivered padded with a variable assignment,
> e.g. "data =
> > > {lat=xxx, lon=xxx}" by the server.
> >
> > > But Micheal: Why this?
> >
> > > JSON is not executable JavaScript and cannot be used cross-domain
> > > without a proxy.
> >
> > > I think, "cross-domaining" is of course possible, but it
> is probably
> > > hard to deal with the results? The server side is called in any
> > > case...
> > > Or do I catch that wrong? For me XMLHttpRequest is not
> cross domain
> > > and cannot be used w/o proxy, that's for sure.- Zitierten Text
> > > ausblenden -
> >
> > - Zitierten Text anzeigen -
> >
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