Re: [thredds] crossdomain.xml

Cross domain files are used by Adobe products like Flash and Flex to add some security to which hosts can access your server. I use thredds services within Flex applications we've developed in Adobe Flex to visualize climate model data. To be able to use Flash/Flex with Thredds services you need to have a cross domain file installed on the same machine that hosts the thredds web application.

It should be installed at ${tomcat_home}/webapps/ROOT/crossdomain.xml

There are lots of variations on what you can put in the cross domain file. The sample one the developer attached basically says any host can connect to this server (with Flash/Flex applications). There have also been some changes on the cross domain syntax from Flash Player 9 to Flash Player 10.

As an example, here is our working cross domain file.

<site-control permitted-cross-domain-policies="master-only"/>
<allow-access-from domain="*"/>

Since we host the thredds server and the Flex web applications on the same machine, I lock down access to only allow hosts within the domain. This means Flash/Flex web applications hosted on can not access our thredds services (primarily WMS for mapping applications).

If any of you Thredds gurus are interested, here is a link to our Adobe Flex web application that maps climate model data via Thredds WMS.

Hope this helps.

On 08/15/2012 09:01 AM, Roy Mendelssohn wrote:
For what it is worth, I went to the URL where he claims to be getting an error, 
and it worked just fine.  The file he sent I believe would open up all 
javascript cross-doman requests.  Not certain that is something you want on 
your server, in particular because I can't replicate his error.

It is possible that there is an error in the next steps after the 
GetCapabilites request, but I would ask him to provide specific examples of 
that.  Unless you are doing proxying to a different machine in your thredds, I 
don't know why a cross-domain request would be made.  I ran into this problem 
with ncWMS, but that was because we were indeed proxying.


On Aug 15, 2012, at 8:26 AM, tom cook wrote:

I just received this email from a developer interested in using our
WMS feeds, but getting errors. I really don't know much about WMS, and
just enabled it the typical TDS manner. He has provided a copy of the
crossdomain.xml file that apparently is the root of his errors. Does
anyone know more about this? Can I just put the crossdomain.xml file
some where in the TDS path to resolve this?

---------- Forwarded message ----------
From: Frank Roberts <froberts@xxxxxxxxxxxxxxxx>
Date: Tue, Aug 14, 2012 at 12:45 PM
Subject: WFS connection to 6km data
To: jimp@xxxxxxxx, tmcook@xxxxxxxx
Cc: Bill Robberson <Robberson.Bill@xxxxxxxxxxxxxxx>, Cheryl Henley

My name is Frank Roberts and I am working with Bill Robberson at US
EPA in San Francisco to make use of your  WFS connection to 6km data
found at the following location:

In working with the above service, I seem to be getting an error.  It
appears that the server may be missing a file at the root of the web

The crossdomain.xml  file is used by some software such as Adobe Flash
when combing services  and it is required for the mash up of services
to work correctly.  I imagine I might be the first person that may
have run into this issue.   The following is a quick right up of what
the crossdomain.xml file does:

Can I get someone to verify the  existence of the crossdomain.xml file
on the server?  In the event that it is missing, I would gladly
provide you a copy of one I already have in existence.  In fact, I
will attach it to this email, if that is of any help.

I know utilization of your service is very important to the EPA, and I
would like to do whatever I can to get access.

Thanks for your assistance,

Frank Roberts

Geo Developer

Phone: (208)699-2712

Innovate! Inc.
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Roy Mendelssohn
Supervisory Operations Research Analyst
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097

e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440

"Old age and treachery will overcome youth and skill."
"From those who have been given much, much will be expected"
"the arc of the moral universe is long, but it bends toward justice" -MLK Jr.

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Oregon State University
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Office Burt Hall 166

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