ArcGIS GeoEvent Server does not ingest non-English characters (for example - Korean language characteres) when an external system is sending JSON data to an input connector and is posted with Content-Type: application/json header.
Verified addressed in the upcoming ArcGIS 11.1 release. Web clients can specify either `application/x-www-form-urlencoded` or `application/x-www-form-urlencoded;charset=utf-8` as the REST request's content type when GeoEvent receiver input specifies `application/x-www-form-urlencoded` as an Acceptable MIME Type. Web clients can also specify `application/json` as the REST request's content type and allow the GeoEvent receiver input to use the default (application/json) as an Acceptable MIME Type.
Strings written out to an output file as JSON display the multi-byte characters.