[OpenLayers-Users] Problems embedding OpenLayers in a Blog
Adam Ratcliffe
adam at prema.co.nz
Wed Dec 23 13:52:09 EST 2009
Images are not subject to the same-origin policy that applies to data
loaded via XHR which is why the map tiles load fine.
One way to circumvent the browser's same-origin policy when loading
data from another domain is by dynamically inserting a script tag in
the DOM and using it to load the data as JSON, this technique is
described in more detail here: http://ajaxpatterns.org/On-Demand_Javascript
I haven't used this technique with OpenLayers, presumably you would
need to implement a custom protocol to integrate with the Vector layer.
Cheers
Adam
On 24/12/2009, at 6:17 AM, jamesmikedupont at googlemail.com wrote:
> Ahh,
> it seems that the tiles are being loaded, but no data. That would
> explain something.
> Of course loading the tiles based on the current scrolling position
> would not be a security issue.
>
> Ok, well I will have to spend some more time to read about this, can
> you please explain on thing :
>
> what is the difference between :
>
>
> new OpenLayers.Layer.GML("OSM", "file.osm", {format:
> OpenLayers.Format.OSM});
>
> and what I was trying to do that did not work :
>
> new OpenLayers.Layer.Vector("Lines", {
> strategies: [new OpenLayers.Strategy.Fixed()],
> minZoomLevel: 1,
> maxZoomLevel: 6 ,
> numZoomLevels: 5,
> protocol: new OpenLayers.Protocol.HTTP({
> url: "test-embed_files/testway.xml",
> format: new OpenLayers.Format.OSM(),
> })
> });
>
> Thanks,
> mike
>
>
> On Wed, Dec 23, 2009 at 5:56 PM, jamesmikedupont at googlemail.com
> <jamesmikedupont at googlemail.com> wrote:
>> I am looking at this example,
>> http://trac.openlayers.org/browser/trunk/openlayers/examples/osm-layer.html
>>
>> It is using GML instead of OSM, and it is also loading from the
>> openstreetmap.org domain.
>>
>> How can this example work if you cannot load map data from another
>> domain?
>>
>> mike
>>
>> On Wed, Dec 23, 2009 at 5:16 PM, jamesmikedupont at googlemail.com
>> <jamesmikedupont at googlemail.com> wrote:
>>> Yes exactly,
>>> but if I host the page on archive.org then I can access the data on
>>> the same domain.
>>> I had a misconception about this whole thing, obviously mashups are
>>> going to create a lot more server sided traffic.
>>> mike
>>>
>>> On Wed, Dec 23, 2009 at 4:29 PM, Marc Jansen
>>> <jansen at terrestris.de> wrote:
>>>> Hi Mike,
>>>>
>>>> as for OpenLayers, it shouldn't be a problem to get it hosted
>>>> nearly
>>>> everywhere since it is only JavaScript. Obviously you cannot use
>>>> any
>>>> datasource, though. Maybe you can set up a proxy that handles the
>>>> requests,
>>>> but I'd doubt that it is possible for your current *.blogspot.com-
>>>> adress.
>>>>
>>>> Regards,
>>>> Marc
>>>>
>>>>
>>>>
>>>> jamesmikedupont at googlemail.com wrote:
>>>>>
>>>>> Thanks for your advice. That is interesting.
>>>>> I never did anything like this, and I feed pretty stupid right
>>>>> now!
>>>>>
>>>>> But it will be possible to host the webpages on archive.org as
>>>>> well
>>>>> and work without the blog itself. It just would be nice to
>>>>> separate
>>>>> the display and the data storage. That effectively reduces the
>>>>> usage
>>>>> of openlayers to people who have control of domains, right? It
>>>>> will
>>>>> not be possible to people to just create maps with any data they
>>>>> want
>>>>> without a server to proxy the data.
>>>>>
>>>>> Now, this example, it displays an openstreetmap map
>>>>> http://osmopenlayers.blogspot.com/2009/12/test-of-osm-server.html
>>>>>
>>>>> but the fetch to :
>>>>> http://www.openstreetmap.org/api/0.6/way/24315294/full
>>>>> that fails, or never returns.
>>>>>
>>>>> But the same one to use open layer to load the data from osm
>>>>> fails :
>>>>> http://osmopenlayers.blogspot.com/2009/12/get-osm-data-directly.html
>>>>>
>>>>> It calles get on this url
>>>>> http://www.openstreetmap.org/api/0.6/way/24315294
>>>>> in the request XMLHttpRequest.js (line 200)
>>>>>
>>>>> the other thing is that I dont get any error message about
>>>>> security
>>>>> problems
>>>>>
>>>>> I found this document here:
>>>>> http://docs.openlayers.org/library/request.html
>>>>>
>>>>> So, realistically it is not possible to host open layers on a
>>>>> blog?
>>>>>
>>>>>
>>>>> mike
>>>>>
>>>>> On Wed, Dec 23, 2009 at 1:37 PM, Marc Jansen
>>>>> <jansen at terrestris.de> wrote:
>>>>>
>>>>>>
>>>>>> Hi Mike,
>>>>>>
>>>>>> I am pretty sure that you aren't allowed to acces datasources via
>>>>>> XHR/AJAX
>>>>>> from other servers than the one the original page is served from.
>>>>>>
>>>>>> see: http://en.wikipedia.org/wiki/Same_origin_policy
>>>>>>
>>>>>> Just a quick guess, though.
>>>>>>
>>>>>> regards,
>>>>>> Marc
>>>>>>
>>>>>>
>>>>>> jamesmikedupont at googlemail.com wrote:
>>>>>>
>>>>>>>
>>>>>>> Hi there,
>>>>>>> I have attempted to embed openlayers in a blog post,
>>>>>>> and am failing! Any help would be appreciated.
>>>>>>>
>>>>>>> using osm data hosted OSM data on archive.org
>>>>>>> http://osmopenlayers.blogspot.com/2009/12/test-embed.html
>>>>>>>
>>>>>>> here is get a octet bytestream because archive org does not
>>>>>>> say the
>>>>>>> right filetype.
>>>>>>> http://ia341335.us.archive.org/2/items/ZCTA_NJ/zip_07003.poly.osm
>>>>>>> this
>>>>>>> returns a 206 partial content and fails.
>>>>>>>
>>>>>>> in a pastebin file that is delivered as text:
>>>>>>> http://osmopenlayers.blogspot.com/2009/12/hosting-on-pastebin.html
>>>>>>> Date Wed, 23 Dec 2009 10:15:43 GMT
>>>>>>> Server Apache/1.3.33 (Debian GNU/Linux) mod_python/2.7.10
>>>>>>> Python/2.3.4
>>>>>>> PHP/4.3.10-22 mod_perl/1.29
>>>>>>> X-Powered-By PHP/4.3.10-22
>>>>>>> Content-Disposition attachment; filename="f28514ba0.txt"
>>>>>>> Keep-Alive timeout=15, max=100
>>>>>>> Connection Keep-Alive
>>>>>>> Transfer-Encoding chunked
>>>>>>> Content-Type text/plain; charset=iso-8859-1
>>>>>>>
>>>>>>> So the problem might be the attachment...
>>>>>>>
>>>>>>> and that data from osm directly again on pastebin,
>>>>>>>
>>>>>>>
>>>>>>> http://osmopenlayers.blogspot.com/2009/12/osm-data-from-xml-output-on-pastebin.html
>>>>>>> data is here :http://pastebin.com/pastebin.php?dl=f290d5ea6 it
>>>>>>> returns a
>>>>>>> 200 ok.
>>>>>>> It returns an : text/plain; charset=iso-8859-1 but does not
>>>>>>> render.
>>>>>>> But there is still nothing there
>>>>>>>
>>>>>>> from osm directly
>>>>>>> http://osmopenlayers.blogspot.com/2009/12/get-osm-data-directly.html
>>>>>>> firebug says :no element found
>>>>>>>
>>>>>>> And my last try was to put the code from osm on the page
>>>>>>> directly,
>>>>>>> also not rendering but the xml is loading.
>>>>>>> http://osmopenlayers.blogspot.com/2009/12/test-of-osm-
>>>>>>> server.html
>>>>>>>
>>>>>>> but nothing is working
>>>>>>>
>>>>>>> would appreciate any tips and help
>>>>>>> thanks
>>>>>>> mike
>>>>>>> _______________________________________________
>>>>>>> Users mailing list
>>>>>>> Users at openlayers.org
>>>>>>> http://openlayers.org/mailman/listinfo/users
>>>>>>>
>>>>>>>
>>>>>>>
>>>>
>>>>
>>>
>>
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