On 02/07/12 10:23, Sarven Capadisli wrote:
Hi,
I was recently told that the callback parameter for a Fuseki service
request doesn't properly wrap the brackets e.g.,
http://worldbank.270a.info/sparql?query=SELECT%20DISTINCT%20*%20WHERE%20%7B%3Chttp%3A%2F%2Fworldbank.270a.info%2Fclassification%2Fvariable%2Fpr%3E%20%3Fproperty%20%3Fobject%7D&output=json&callback=lodlive
Note the missing closing bracket, ')'.
I've briefly checked:
src/main/java/org/apache/jena/fuseki/servlets/ResponseResultSet.java
Not tested: Should the closing bracket line be out.println(")") ?
No - it's much, much weirder than that!
The code has:
if ( callback != null )
{
out.print(")") ;
out.println() ;
}
so that's OK.
Or is it?!
Your HTTP request allowed for gzip (Accept-Encoding: gzip, deflate). So
the stream is gzip'ed.
It seems that Jetty closes gzip'ed streams when you flush an HTTP
response. It merely flushes an un-compressed stream.
Jetty's GzipResponseWrapper ==>
public void flushBuffer() throws IOException
{
if (_writer!=null)
_writer.flush();
if (_gzStream!=null)
_gzStream.finish(); <--********
else
getResponse().flushBuffer();
}
So "out", or the underlying stream, is closed and that code throws an
IOException. But can't set the HTTP status code because
HttpServletResponse.flushBuffer has been called and the 200 already
sent. This is a Jetty bug - the servletAPI documentation does not say
that flushBuffer is the end of the request.
If you don't set Accept-Encoding it works just fine - flush means flush
and the trailing")" is written just fine.
Oddly: Tomcat6:
https://issues.apache.org/bugzilla/show_bug.cgi?id=48738
Yuk.
Thanks for the report ... need to code round this.
Andy
-Sarven
