Messages for Datasources

When a datasource is called in appNG in scope of a page, the messages added to the field processor are shown on the page. But a datasource can also be called as a service. In that case, there is no page where messages can be displayed. The messages added to the fieldProcessor are stored in the session and will be added on next action call. This leads to some disadvantages:

• Error messages cannot be displayed at the place they are belong to
• Even if there are error messages during processing of a datasource, the http status code is always 200 if the datasource is called as service
• Error messages are added to any action which is called afterwards, but the error often does not belong to that action