How to send http headers while using jsonp proxy?

[shri_iitk]

I am trying to get data from web services from my app to load a list and to load more on scroll using pull refresh & ListPaging plugins. I tried this with flickr API and it works fine, but problem comes when I try to access our own services because they expect "Authorization" header with Base64 encoded data and "Accept" header to decide format of response.This is how I have defined my store:

Ext.define('myshop.store.CatalogListStore',{
    extend:'Ext.data.Store',
    requires: [
        'myshop.model.CatalogListItem'
    ],
    config:{
        model:'myshop.model.CatalogListItem',
        autoLoad :true,
        proxy: {
            type: 'jsonp',
            url: 'http://192.168.23.89:7003/xxx-service/test/catalog/list',
            useDefaultXhrHeader : false,
            withCredentials:true,
            method : 'GET',
            headers: {
                'Accept': 'application/json',
                'Authorization': 'Basic YX5iOmM='
            },
            extraParams: {
                format : 'json',
                pagesize : 10
            },
            reader: {
                type: 'json',
                rootProperty: 'categories.data'
            }
        }
    }
}

This is what I see in Chrome's network console:

Request URL:http://192.168.23.89:7003/xxx-service/test/catalog/list?_dc=1354529083930&format=json&pagesize=10&page=1&start=0&limit=25&callback=Ext.data.JsonP.callback2
Request Method:GET
Status Code:403 Forbidden
**Request Headers**
Accept:*/*
Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Host:192.168.23.89:7003
Referer:http://localhost/myshop/
User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.11 (KHTML, like Gecko) Ubuntu/12.04 Chromium/20.0.1132.47 Chrome/20.0.1132.47 Safari/536.11
**Query String Parameters**
_dc:1354529083930
format:json
pagesize:10
page:1
start:0
limit:25
callback:Ext.data.JsonP.callback2
Response Headersview source
Content-Length:0
Content-Type:text/xml
Date:Mon, 03 Dec 2012 10:04:40 GMT
Server:Apache-Coyote/1.1

If I use Poster to access these services with Authorization header I am able to see response but since Headers are not passed in request I am getting "403 forbidden" status.
If I use headers like this it works :

Ext.Ajax.request({
        url: 'resources/data/templates.json',
        headers: {
            'Accept': 'application/json',
            'Authorization': 'Basic YX5iOmM='
        },
        success: function(rsp){
        }
});

but I cannot do this because I want to use listPaging plugin.

[mitchellsimoens]

You won't be able to as JsonP uses a <script> tag. I would recommend using Ajax and having your server support CORS.

[shri_iitk]

For time being I have disabled Authorization header requirement and moved ahead with JSONP but I am sure in future I have to come back and see how to add CORS support to my server. If you know how to do that in CXF based web-services served by tomcat, please let me know.

[shri_iitk]

But what's the problem in supporting HTTP headers in JSONP because it seems like legitimate requirement from my point of view. More and more apps are talking to web services these days and server management team never feels comfortable enabling CORS on production servers, so having this feature will make life simpler.