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loading JSON data from an API from javascript

i need to consume a web api, which is located here
http://46.253.202.174:8080/ws-api/v1/rest/zdata/codesByJurAndUsage?jur=Boston,%20MA&usg=barber
I don't have any details of how it is implemented or access to the code of the API, I'm just trying to consuming the API, I can see the JSON return data if i type the url in the browser, but when i'm trying to call the API using $.getJSON, it gave me an access denied error. I understand that its a cross domain issue. I also tried a few other things, like jsonp data type, with no success. My question is, if i am able to see the results in a browser, shouldn't i be able to get the results from the scripts, or its no necessarily true?
Secondly, is there any other way, if the things i have tried so far was not successful.
thanks

You are correct, you won't be able to load this data via $.getJSON due to the Same Origin Policy restrictions. You'll need to load it via JSONP, or, if the service doesn't support JSONP (which it looks like it doesn't), via a proxy. A couple of options:
You can set up a proxy on your own server via PHP or another server-side language. This will allow you to request the data from your own server, getting around the same-origin restriction. You might look at a project like Simple PHP Proxy for this purpose.
You can use YQL as a proxy - this sends the data through Yahoo!'s servers and then you can load it via JSONP. Applying this technique with jQuery is discussed in this article.

Accessing DOM element of a webpage without opening it

I have started working on JavaScript. I want to count the number of frames/anchors on yahoo homepage without opening it(means I don't want to load the page in another window or frame). I didn't find a proper solution for this without using AJAX.Can't we create a document object referring to remote page?
As I am using JavaScript without any framework, can someone guide me how to do this?

You have very few options if you're working on the client side only. This is primarily because you'll be dealing with the dreaded, but necessary, cross-domain policy. However, even if you don't have cross scripting issues, it won't be possible to accomplish this without AJAX. You'll need to make a request to a server for the page's HTML somehow. I would suggest taking a look at YQL as it appears to solve the cross-domain issue.

You'll have to execute an HTTP request to get the HTML string to feed into a DOM object. AJAX is the easiest way to do that, why do you want to avoid AJAX?
In plain old Java you can create a DocumentBuilder and source a document with a URL, but I don't believe this is available in javascript.

Avoid x-domain solutions

I'm currently working on a web application that customers can add to their webpages by adding a javascript link to a js file on my server. The application read all the javascriptfiles from my sever, but I still get an error when trying to use ajax to get data from my database. I didn't think that would be a problem because the files is on my server.
Can I fix this or do I have to make a cross-browser solution? I don't have any control over the costumers server.
Thanks in advance
Mikael

This is not possible: When you execute a remote script, it runs in the context of the containing document.
There are some popular workarounds for this:
Using an iframe, which fixes the cross-domain problem but doesn't integrate well with the remote site (e.g. no custom styling)
Using JSONP to make cross-domain Ajax requests (detailed explanation here)
Using a server-side proxy script (not an option in this scenario)
Using YQL (I'm not familiar with this but it's said to work)

The same origin policy is based on the host document not the script itself.
You need to use a cross domain ajax technique.

Download file using ajax and webservice

There is this 3rd party webservice. One of the public webmethods available is a GetDocument() method. This method returns a Document object. The Document object has properties for File(byte[]), ContentType(string) ect.
My Question : Can I subscribe to this service using javascript(mootools) + ajax + JSON, return the document object, in this case an excel document, and force the file download?

It is true that typically you cannot initiate a download from JavaScript, but there is a flash component, Downloadify that does enable client side file generation.
So you can serve files for download from HTML/JavaScript.
With that problem solved, you still have the problem of how to get the data that you wish to serve from the source web service.
3rd party implies XSS (cross site scripting) which is a no-no using XmlHttpRequest (Ajax).
A possible solution to this problem could be to use a common hidden IFrame technique to get the data.
Simply have an appropriate (hidden?) form that correctly posts to the web service and point it's action to an hidden IFrame element upon which you are trapping the Load event and parse the data returned.
But current browsers have different levels of security measures that limit your ability to access IFrames with an external source so you are actually stuck here. Sorry to get your hopes up.
The only practical robust way to accomplish what you would like to do is to have a local server side script that can act as a proxy between your HTML/JavaScript and the external web service.
Using such a proxy, you can simply go back to using Ajax to get your data to serve up with Downloadify.
But then, since you are using a server script to get the data, why not just serve the data from the script for download?
These are just my observations on the problem domain you present.

How can i get around the same origin policy?

I need to use AJAX to get the content of another page located on a different server from the one the AJAX is loaded from. The AJAX needs to send a POST request then return the result. how can i do this?

Set up proxy on your own server. Have your server call theirs and return the result.

if you control both servers, you can use one of the HTTP header fields for cross-origin resource sharing:
http://www.petefreitag.com/item/703.cfm
https://developer.mozilla.org/En/HTTP_access_control

There is no way to go around that policy. This policy is there for very good reasons.
That is also no problem as long as you're in control over the web application. You could simply redirect the call to the other server from your webserver and pass the result. This would work out like a proxy.

If you want to do that on the client and cross browser, you need some cooperation from the other server.
Either by:
1) using JSONP (inject a script tag with a callback function)
Only GET calls are possible though.
Security is an issue as the script has access to all resources in that page(data, cookies, ...).Here's a post that explain how to sandbox them and keep the data in your page safe.
2) POST looks possible using Kris Zip's window.name technique
If the cooperation from the other server is impossible, the server proxy as described in other answers is, to my knowledge, the only option left.