Application Structure:
  • ViewModel-stores
    • app
      • model
        • Student.js
      • view
        • student
          • StudentGrid.js
          • StudentViewModel.js
    • app.js
    • default.html
    • ext-5.1.0

Example: stores in ViewModel.

model\Student.js 
Ext.define('SchoolApp.model.Student', {
    extend: 'Ext.data.Model',
    idProperty: 'Id',

    schema: {
        namespace: 'SchoolApp.model',
        proxy: {
            type:'ajax',
            api: {
                read: '/ExampleService.svc/students/'
            },
            reader:{
                type:'json',
                rootProperty:'data'
            }
        }
    },
    fields: [
        { name: 'Id', type: 'int' },
        { name: 'firstName', type: 'string' },
        { name: 'middleName', type: 'string' },
        { name: 'lastName', type: 'string' },
        { name: 'birthDate', type: 'date' },
        { name: 'address1', type: 'string' },
        { name: 'address2', type: 'string' },
        { name: 'city', type: 'string' },
        { name: 'state', type: 'string' }
    ]
    
});

Preview