Skip to content

More robust check of web resources #3466

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
shroffk merged 1 commit into from
Jul 10, 2025
Merged

More robust check of web resources #3466

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
37 changes: 13 additions & 24 deletions ...isplay/model/src/main/java/org/csstudio/display/builder/model/util/ModelResourceUtil.java
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*******************************************************************************
* Copyright (c) 2015-2021 Oak Ridge National Laboratory.
* Copyright (c) 2015-2025 Oak Ridge National Laboratory.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
Expand Down Expand Up @@ -330,31 +330,20 @@ private static boolean canOpenUrl(final String resource_name)
logger.log(Level.WARNING, "URL {0} is not a URL", new Object[] { resource_name });
return false;
}
// This implementation is expensive:
// On success, caller will soon open the URL again.
// In practice, not too bad because second time around
// is usually quite fast as result of web server cache.
//
// Alternative would be to always return the stream as
// a result, updating all callers from
//
// resolved = ModelResourceUtil.resolveResource(parent_display, display_file);
// stream = ModelResourceUtil.openResourceStream(resolved)
//
// to just
//
// stream = ModelResourceUtil.resolveResource(parent_display, display_file);
//
// This can break code which really just needs the resolved name.

try
final String escaped = resource_name.replace(" ", "%20");
// Opening the URL stream to check availability seems expensive.
// On success, we'll soon do this again to actually read.
// But 'openURL' uses a cache, the next time around
// we already have the content.
// Attempts to "only check" without reading, for example
// new URL(...).openConnection().connect()
// turned out to sometimes succeed even if the document doesn't exist
// on the web server. Details might be related to the behavior
// of site-specific intermediate proxies.
// In any case, this seems the most reliable approach
try (InputStream stream = openURL(escaped))
{
// final InputStream stream = openURL(resource_name);
// stream.close();
//Test only if the page exist and not read the content
final String escaped = resource_name.replace(" ", "%20");
URL resource = new URL(escaped);
resource.openConnection();
return true;
}
catch (Exception ex)
Expand Down