The client stated that we have a REST API available to us. In fact, they have other Ext JS applications to be built on top of this API and so we're lucky. The data is returned as JSON that can be easily consumed by Ext.data. The customer provided documentation on how the API operates:
API Endpoint: http://localhost:3000
GET /pages
Accepts: n/a
Returns: [{ id: 1, text: 'label', children: [] }, { id: 2, text: '', children: [] }]
PUT /page
Accepts: {"published":true,"stub":"our-work","body":"Our Work.","id":"5e30c0a3-729a-4719-a17f-7e2286576bda"}
Returns: {"success":true}
POST /page
Accepts: {"label":"New Page","text":"New Page","leaf":true,"id":"Unsaved-1","parentId":"5e30c0a3-729a-4719-a17f-7e2286576bda","published":true,"stub":"new-page","body":"A New Page."}
Returns: [{"clientId":"Unsaved-1","id":"2ae28c61-cc6e-4a98-83ee-f527f4b19f1e","text":"New Page","body":"A New Page.","published":true,"stub":"new-page","leaf":true}]
DELETE /page
Accepts: {"id":2}
Returns:...