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Is there a way to read a local netcdf file from a web application?

We are building a web service for data analysis and would like to access netcdf files from the local machine where the browser is running. Javascript offers a file browser, but (for security reasons as I learned) it will automatically upload a file after selection, instead of allowing (read-only) access to it. This presents a show-stopper, because the netcdf files can be HUGE. Note, that the netcdf format and API explicitly allow slicing and extraction of individual variables, which is one reason why the format is so popular.
Now, some research into this issue revealed that the server-client architecture normally doesn't allow access to the local file structure to prevent spying. On the other hand, in HTML5 there is a file API which supports exactly the kind of operations we need -- except that you can access portions of a file by specifying byte ranges, but there is no netcdf API available; hence one would be left again with copying the entire file before being able to slice it on the server.
Of course, the other option are web services such as OpenDAP which are meant to do exactly what we want, i.e. access parts of a netcdf file over the internet. However, this of course requires that every user would have to install the OpenDAP server before they could access their local files from within the web service. (Or, at a minimum they would have to install a web server so that one could access the file via http://localhost/...).
So: does anyone know of a solution to read specific portions of a local netcdf file from a web application? Specifically, are there javascript tools available for this?

Currently you can use netcdfjs, that it's a javascript library that allows to read NetCDF v3 files. Because it's a NodeJS package you can run it server side, and for regular size files you can read it online, here you have an example.

There are no Javascript tools to read NetCDF, but there are Java libraries: http://www.unidata.ucar.edu/downloads/netcdf/index.jsp.
You could deploy a Java Applet to read the NetCDF file locally. From there you could have the Applet try to process the file, or communicate with a backend service, or even try to call on the Applet from Javascript: http://docs.oracle.com/javase/tutorial/deployment/applet/invokingAppletMethodsFromJavaScript.html.

There are no specific Javascript libs for reading NetCDF, as far as I know. But let me drop some thoughts:
As you say, you can install a local webserver, and use a server-side language to execute a program that reads the file in your disk. You could use a command-line software called ncdump-json. I intentionally wrote this software for that purpose.
You say that you don't want to install software like OpenDAP or webservers, but maybe a desktop app, a standalone .exe would be OK for you. Using node.js plus chromium (this is called nw.js) you have a program that is at the same time a nodejs server, and a chromium browser. This way you can write a web application that reads the data (e.g. using the embedded nodejs server and spawning ncdump-json...).
And now the simplest scenario, a 100% client-side solution... I think this can only be achieved using Javascript... or anything that can "compile to" Javascript. We need to have the netCDF libraries in Javascript, is that possible? I guess so. Emscripten is a LLVM-to-Javascript compiler, and netCDF is C so it has to be possible to compile it with clang/LLVM, therefore it has to be possible to use Emscripten to have a netCDF JS library version with almost no effort, without having to write from scratch (and also maintain) a JS port. If I'm not wrong, to random access the files there's the method slice in the html5 file api, so that should not be a problem.
Hope I helped.

how to read text from input file in javascript?

I have a text file i want to read in my html page,both are in the same directory and i am not running a server. I intend that my users use the script offline(basically text manipulation based on expressions and preserving new line characters) .
I tried ajax call but mostly cross domain origin problem occured and i know most of the users will have this security tighened up in many browsers , so its not of use to circumvent this in only in my browser.
I want to support many browsers including old browsers as in IE7,8 etc which do not support HTML5 filereader.for the same reason reading using filesystemobject or activex is not good.
Reading the file after user select it as input , is this possible?Otherwise i would have no option then using other technologies like php,java etc which may expect my user to setup these.
Please excuse me if i am repeating this but i am a beginner web developer. I know that reading local files via javascript is not possible but is there any other way?

If you can't support FileReader, then the answer is pretty much no (at least, if you want to support a large range of browsers rather than rely on convenient feature x of browser y). Unless : you indeed increase the requirements for running the application and get some sort of local server going (for instance node.js, Apache, TomCat, etc. but like you said this will greatly increase the requirements and become cumbersome for users).
You could also rethink what it is you're trying to achieve. What are the contents of the file you want to read ? Can't these contents be part of the HTML file you're serving to your users (i.e. a large JSON Object inside a script-tag ?)
On possibility of using node.js:
Node.js is quite easy to install and assuming you are requiring from your users to install it, you can use it as a local server, which is a nodejs script of about two lines in size :). Running it locally would also omit the need to upload anything anywhere as you can directly read from the file system using the fs-object (see sitepoint.com/accessing-the-file-system-in-node-js).
STILL: from both a design and ease-of-use-point of view you might want to resort to using either another technology, or include the text file content inside the HMTL file

How to parse a CSV file into an array in Javascript

From what i understand, This usually has to be done server side. However i have read that it is possible to point to the csv file in a .js file. This would be more useful to me as i am not messing around with server side code and stuff for this project and will be all on my local machine. I saw an article with example code to do this somewere however i can't locate that article atm. Anyone know how to do this?

To access any file from the system you have to use directX in IE or read up on how to use NPAPI for mozilla support.If you are willing to use HTML5, check out its filereader API here.

How to read local (Client) file with GWT?

I would like to use GWT to read and parse local csv file.
EDIT: Local file here means client file.
I know I can use HTML5 with javascript to achieve that, but I would like to use GWT to do it.
One way of doing it is by using JavaScript Native Interface (JSNI), however I think it beats the purpose of using GWT.
Another way of doing this would be upload the file to server, and send it back as a json. But I feel it's not the best way of doing it.
Please advise. Thanks.
EDIT: I intend to design a desktop app, so I try to avoid using any web-server scripting.

Using jsni doesn't beat the purpose of gwt, sometimes you need to use it as a wrapper to functionality not yet available in gwt or an external javascript library. Instead of writting jsni access to the file api you can use one of several third party libraries available that implement html5 file access, like http://code.google.com/p/lib-gwt-file

A quick search returned this SO question: Read text file in google GWT?
Although GWT doesn't support java.io.InputStream, it looks like you could make a request to your CSV File and then parse it.
Remember that if you will host on AppEngine, you won't have a filesystem available so you'll have to have the files hosted elsewhere.

What is the best way to upload a folder to a website?

I need an easy way to allow users to upload multiple files at once (ie I need to allow a user to upload a folder). I do not wish to put the burden of zipping on the user.
I would prefer to avoid Flash or variants if possible. I'm looking for a straight javascript / HTML solution if it is possible. Please note, this rules out the answers at: What is the best client side browser library to upload multiple files over http?.

You won't be able to do it with just HTML and Javascript. I'd recommend trying Fancy Upload, a MooTools plugin for multiple file uploads. It uses a mixture of JavaScript and Flash, but degrades gracefully. It works with all major browsers including IE6 and there is also a Flash 10 compatible release available for download (though the demo hasn't been updated yet).
Update (2012-11-26):
Multiple file uploads are possible with valums or blueimp file uploaders.
For recursive directory uploads, your best solution is using Chrome 11's new folder upload API. It also seems to work on Firefox if you use a vendor prefix.

With Firefox 42 and Edge having implemented the new directory upload proposal we'll finally able to do cross-browser directory uploads. The APIs are nasty enough that you may want to check out my wrapper, uppie.

If you're avoiding Flash (and presumably Java?) the JS/HTML-only solution still requires single-file inputs, but essentially you attach an onchange event to your input, adding a new input to the DOM whenever a file is selected.

Multiple file uploads are possible with valums or blueimp file uploaders.
For recursive directory uploads, your options are more limited:
Your best solution is using Chrome 11's new folder upload API. It also seems to work on Firefox if you use a vendor prefix.
This is also possible cross-browser with a Java applet. However the % of folks with a JRE installed has gotten pretty low these days (< 70%)

This isn't a pure js/html solution. As EndangeredMassa has pointed out, it's not possible. In fact, this idea is an IE/Windows only solution. I don't recommend it, but it can work.
So, all disclaimers aside ...
Many years and several employers ago, we used to do some client side stuff that instantiated the FileSystemObject. It would iterate through each of the files and pass them through to the server one at a time. Can't remember the details of how we did that :o(
Anyway, this usually meant that the client box would need to have to add the site to the list of trusted sites and give trusted sites a bunch of permissions that are turned off (for very good reasons). Stuff like the ability to Initialize and script ActiveX controls not marked as safe. That kind of thing.
I know that this isn't a perfect answer, but it could point you in the right direction.

FTP? And if necs, wrap in Java Applet, ActiveX or whatever you want.
If not, although you don't want flash, SWFUpload is quite cool, you may want to reconsider it as a decent option.

Here is pure JS solution using ExtJS library