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https://issues.apache.org/jira/browse/OLINGO-858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15137228#comment-15137228
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Dirk Mahler commented on OLINGO-858:
------------------------------------
Hi Christian,
there's no chance of handling errors while streaming is in progress as the
headers are already written to the ServletOutputStream. But I don't know if
this is really a problem:
{code}
public ODataResponse readEntitySet(final GetEntitySetUriInfo uriInfo, final
String contentType) throws ODataException {
...
List<Map<String, Object>> entries = ... // user code for creating entries in
the feed
...
return EntityProvider.writeFeed(contentType, entitySet, entries,
EntityProviderWriteProperties.serviceRoot(
getContext().getPathInfo().getServiceRoot()).build());
{code}
Entries can be a List which only provides an Iterable/Iterator that is
transformed into the InputStream which is used to write to the
ServletOutputStream. So the user code can create a valid ODataResponse object
if it is sure that the iterator can fetch data (e.g. after successful execution
of a query and providing the iterator based on the result set) or create an
error if anything went wrong at this stage. Of course there's still a chance
that fetching data from the iterator fails for some reason (e.g. connection to
DB is cut-off) but that's a bit like that the WiFi is turned off on the client
that receives the data - he gets some non-parseable XML or JSON and needs to
deal with that properly.
Actually there's another problem: If the iterator like in the given example is
backed up by a JDBC result set (i.e. a resource) then it must be closed after
processing it. If everything goes well the iterator implementation may do this
on it's own if the last row has been reached - but there's currently no chance
of detecting a broken connection to the HTTP client. In our project I solved it
by putting the JDBC connection in the request scope of a CDI container - but
this is very dependent on the technical context.
> org.apache.olingo.odata2.api.processor.ODataResponse enity is not streamed
> --------------------------------------------------------------------------
>
> Key: OLINGO-858
> URL: https://issues.apache.org/jira/browse/OLINGO-858
> Project: Olingo
> Issue Type: Improvement
> Components: odata2-core
> Affects Versions: V2 2.0.5
> Reporter: Mitko Kolev
> Assignee: Michael Bolz
>
> The entity of the {{org.apache.olingo.odata2.api.processor.ODataResponse}} is
> not streamed.
> {code}
> ODataResponse.newBuilder().entity(someInputStream).header("Content-Type",
> "application/octet-stream")
> .status(HttpStatusCodes.OK).build()
> {code}
> It would make sense to stream this directly in the HTTP response.
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