Error loading ROOT file from S3 storage in JSROOT versions 7.10 and later

[grzanka]

I am able to open certain ROOT files hosted on S3-compatible storage (https://s3.cloud.cyfronet.pl/) using the JSROOT instance at https://jsroot.gsi.de/ with version 7.9.3. For example, this file loads without issues:

https://jsroot.gsi.de/7.9.3/?file=https://s3.cloud.cyfronet.pl/datarawlv3v1/lgad_agg_v1.root

When using version 7.10.0 with the same ROOT file, I get the following error:
https://jsroot.gsi.de/7.10.0/?file=https://s3.cloud.cyfronet.pl/datarawlv3v1/lgad_agg_v1.root

Ssame error occurs when using the latest JSROOT version:
https://jsroot.gsi.de/latest/?file=https://s3.cloud.cyfronet.pl/datarawlv3v1/lgad_agg_v1.root

For reference, the CORS configuration on the S3 storage side is set as follows:

<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
  <CORSRule>
    <AllowedMethod>GET</AllowedMethod>
    <AllowedOrigin>*</AllowedOrigin>
    <AllowedHeader>*</AllowedHeader>
    <ExposeHeader>content-range</ExposeHeader>
    <ExposeHeader>content-length</ExposeHeader>
    <ExposeHeader>accept-ranges</ExposeHeader>
  </CORSRule>
</CORSConfiguration>

Please let me know if there is any additional information I can provide or if there is a workaround to load ROOT files from S3 storage in JSROOT versions 7.10 and above.

[linev]

Thanks to reporting the problem,
Original problem is on s3 server side which returns wrong data in http response headers.
jsroot 7.9 was able to recover from this situation, but jsroot 7.10 and later - not.
I will try to provide patch which let recover also in jsroot 7.10.

But one also should see how s3 problem can be fixed.
It is about multirange request.

Once I am back from ROOT workshop I will provide more info about s3 problem.

[grzanka]

Thanks !
We can also discuss at ROOT workshop in person :)

[linev]

We can also discuss at ROOT workshop in person :)

Yes, any time.

2173965 fixes the problem.

[linev]

Problem can be seen with following curl request:

curl -ik -L https://s3.cloud.cyfronet.pl/datarawlv3v1/lgad_agg_v1.root  -H "Range: bytes=1000-1100,1200-1300" --output -

I see that only first segment is returned by the server:

HTTP/2 206 
date: Thu, 20 Nov 2025 10:47:07 GMT
content-type: application/octet-stream
content-length: 101
content-range: bytes 1000-1100/1835245
accept-ranges: bytes
last-modified: Wed, 19 Jun 2024 20:02:29 GMT
x-rgw-object-type: Normal
etag: "be5b12df0504fa5cc48b55b3cb979d13"
x-amz-meta-mtime: 1718827347
x-amz-request-id: tx000000000000000478c8b-00691ef1ab-2629789e-prod
strict-transport-security: max-age=31536000; includeSubDomains

So jsroot should fall back to one segment per http request

[linev]

I implement #374 which will improve behavior also in case of server which does not support multi-range requests. Also now JSROOT will not submit requests with unsorted ranges - which prevents failures with some servers. All together PR will significantly improve io performance with TTree

[linev]

Now master branch will try to avoid "complex" requests making live of http server easier.