Dan Haywood created ISIS-2119:
---------------------------------
Summary: Increase timeout to avoid occasional exceptions when
download Blobs
Key: ISIS-2119
URL: https://issues.apache.org/jira/browse/ISIS-2119
Project: Isis
Issue Type: Bug
Affects Versions: 1.17.0
Reporter: Dan Haywood
Assignee: Dan Haywood
Fix For: 1.18.0
On a slow connection, can get occasional exceptions when downloading a blob...
that the behaviour cannot be found on the entity. There's not a lot to go on.
Inspecting the returned payload though, I discovered at the end:
{code}
<evaluate><![CDATA[(function(){setTimeout("window.location.href='./orders.Order:7975?24-1.IBehaviorListener.0-'",
10);})();]]></evaluate>
{code}
which gave me the clue. The relevant code is in
ActionResultResponseHandlingStrategy:
{code}
SCHEDULE_HANDLER {
@Override
public void handleResults(
final ActionResultResponse resultResponse,
final IsisSessionFactory isisSessionFactory) {
final RequestCycle requestCycle = RequestCycle.get();
AjaxRequestTarget target =
requestCycle.find(AjaxRequestTarget.class);
if (target == null) {
// non-Ajax request => just stream the Lob to the browser
// or if this is a no-arg action, there also will be no parent
for the component
requestCycle.scheduleRequestHandlerAfterCurrent(resultResponse.getHandler());
} else {
// otherwise,
// Ajax request => respond with a redirect to be able to stream
the Lob to the client
ResourceStreamRequestHandler scheduledHandler =
(ResourceStreamRequestHandler) resultResponse.getHandler();
StreamAfterAjaxResponseBehavior streamingBehavior = new
StreamAfterAjaxResponseBehavior(scheduledHandler);
final Page page = target.getPage();
page.add(streamingBehavior);
String callbackUrl =
streamingBehavior.getCallbackUrl().toString();
target.appendJavaScript("setTimeout(\"window.location.href='" +
callbackUrl + "'\", 10);");
}
}
},
{code}
What's happening here is that response from the ajax call to invoke the button
is the fragments to rebuild the page ... it's not possible to also return the
BLOB. So the Ajax instead sets a timeout to download that Blob as a separate
web call.
Experimenting with this code, if the behaviour is stripped off (everything
after the "?") then the download doesn't occur; so this is needed.
Since I've seen the problem mostly with large docs and on a slow connection, my
guess is that this is some sort of race condition. Since we can wait a bit
more than 10ms, my suggestion is to increase the timeout to 250ms.
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