NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Turning this on by default is not a good idea. As I indicated elsewhere, if data leaks, then unidata/opendap/... are responsible and that makes us look really bad. =Dennis Heimbigner Unidata Roberto De Almeida wrote:
That was fast, Tom! How does this work, does it add an option for turning on CORS on THREDDS? As I was saying to Dennis, what I'm suggesting here is: Javascript is becoming a major player as a programming language, and if we want our data to be widely accessed and consumed by the new generation of applications in ways that we cannot anticipate, we should add these headers. If security is important we can explain to users how to configure authentication, how to setup SSL certificates, and how to turn off CORS (or restrict the hosts instead of using a wildcard). I think this should be on by default (like I did in Pydap) because otherwise no one will turn it on, and all the data currently available via OPeNDAP will be inaccessible to Javascript, because this is not a policy that can be changed on the browser. But if we start doing it now, providers will eventually upgrade their servers, and maybe next year we'll have WebGL applications that can display data from any DAP server on the browser in 3D, and analyse it using asm.js<http://ejohn.org/blog/asmjs-javascript-compile-target/> . --Rob On Wed, Apr 24, 2013 at 12:52 PM, Tom Kunicki <tkunicki@xxxxxxxx> wrote:I've created a maven project to create a CORS enable thredds war: https://github.com/tkunicki-usgs/thredds-cors CORS is useful for working around single origin issues in browser apps. A CORS enabled server essentially tells the browser that it's ok to let code loaded from a different server utilize resources from the CORS enabled server. Tom Kunicki Center for Integrated Data Analytics U.S. Geological Survey 8505 Research Way Middleton, WI 53562 On Apr 24, 2013, at 2:11 PM, Dennis Heimbigner <dmh@xxxxxxxxxxxxxxxx> wrote: Perhaps more concretely, the thredds server currently supports access controls such as passwords and client-side keys. How would CORS affect those? =Dennis Heimbigner Unidata Roberto De Almeida wrote: Hi, guys! In 2006 I wrote an implementation of an OPeNDAP client in Javascript called jsdap (https://code.google.com/p/jsdap/). At the time Javascript was still a toy language and the XML HTTP Request (XHR) was unable of handling binary data, but I managed to hack a full client that worked in all major browsers (including IE by injecting vbscript!). And while it was written more as a proof-of-concept the client is actually used in some data portals like http://www.ifremer.fr/oceanotronPortal/. (A Node.js OPeNDAP server was also added 3 years ago.) Fast forward 7 years and we now have a lot of new technologies on the table: a new XHR object with support for binary transfers, typed arrays and WebGL. I've been playing again with using Javascript as an OPeNDAP client, in particular to display real time information from OPeNDAP servers. I have set up a small OPeNDAP server on one of my VPS streaming the system load information: http://vps.dealmeida.net:5000/.dds http://vps.dealmeida.net:5000/.das This is an infinite dataset (try "curl http://vps.dealmeida.net:5000/.asc "), and it will keep streaming the data at one record per second until the connection is broken. Keep in mind that this is a regular OPeNDAP Sequence, and nothing was changed in the specification to make this work. Nevertheless, I'm not aware of OPeNDAP clients that can access the stream other than the development version of Pydap. On another machine I have a widget displaying the information on a real time graph: http://dealmeida.net/opendap-streaming/ You can see how everything was implemented on this Mercurial repository< http://code.dealmeida.net/opendap-streaming/src/356dde80f6e55603c2ab7e581244015663504fda?at=demo.The data is displayed by fetching the .dods response and parsing it. We still need a few hacks to do this, but only because the data is being streamed (Mozilla handles it nice; Chrome cannot stream binary data, so it still fetches it as string). Handling regular OPeNDAP datasets should be pretty straightforward with the new XHR, and I plan to rewrite jsdap as soon as I have some free time. *Now to my request:* the only reason that the demo works -- having a page in one host displaying data from an OPeNDAP server on another -- is because I enabled< http://code.dealmeida.net/pydap/commits/4c2d38b5822ba8f5f61e83bcb23230a2ca7e5da1 CORS <http://en.wikipedia.org/wiki/Cross-origin_resource_sharing> on Pydap. By default, now all DODS, DAS and DDS responses from Pydap have the following additional headers: Access-Control-Allow-Origin: * Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type These headers (the first one, actually) allow the responses to be accessed through XHR from any host. As far as I know there is no downside in doing this. Even if your server use cookies for authenticating access to certain datasets the cookies *will not* be sent unless the Access-Control-Allow-Credentials header is set (and set to true), which would allow other sites to "steal" your data and download it by impersonating a logged user. My request is that all OPeNDAP servers enable CORS from any host by default today, at least in the DODS, DAS and DDS responses; and if not by default, at least as an option. This way, by the time Javascript matures enough so that its performance on the browser becomes comparable to desktop applications we can start building rich web applications that use all the data available through OPeNDAP. Some resources About CORS: http://en.wikipedia.org/wiki/Cross-origin_resource_sharing / https://developer.mozilla.org/en-US/docs/HTTP/Access_control_CORS Security concerns: https://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity Thank you, Rob _______________________________________________ thredds mailing list thredds@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/ -- You received this message because you are subscribed to the Google Groups "pydap" group. To unsubscribe from this group and stop receiving emails from it, send an email to pydap+unsubscribe@xxxxxxxxxxxxxxxx. To post to this group, send email to pydap@xxxxxxxxxxxxxxxx. Visit this group at http://groups.google.com/group/pydap?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
thredds archives: