JSONP proxies only support read-only function in Sencha Touch 2.1.1

While in the process of implementing a JSONP proxy writter the following message will pop up when running the code:

Error: [ERROR][Ext.data.proxy.Server#create] JsonP proxies can only be used to read data.

There is nothing in the Sencha Touch documentation, that tells me that a proxy writer can not be used.

After looking at the framework code it was clear to me, that the source code had not been implemented.

With that, you really do need a JSONP writer, otherwise you have to implement the logic yourself or switch back to an AJAX proxy.

There is nothing in the release notes to Sencha Touch 2.2.0 beta 1 that leads me to believe, that any updates on the subject are forthcoming.