THttpServer and online modified files

Dear ROOT community,

I am working on a GUI using THttpServer, when I open my web page on my browser, and access some .log/.txt files from it, I don’t see them to be updated automatically once I write into those files, I need to refresh the page to get the last changes. Is there a way to make it more “dynamical” please ? Here is a snippet of the code I am using:

WebInterfaceServer::WebInterfaceServer(int port)
    : TNamed("WebInterfaceServer", "WebInterfaceServer") {

  m_http_server = new THttpServer(("http:" + std::to_string(port) + "?nocache;global").c_str()); 

  std::string files_path = "/PATH/TO/MY/FILE";

  m_http_server->AddLocation("Index/", files_path.c_str());

  std::string webinterface_path = "/PATH/TO/MY/WebPage.html";


Any kind of help or suggestion will be highly appreciated, thank you.

Best regards,

Dear Abdelhamid,

Thanks for the post. This is a very specific question to which I hope @linev can reply.


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Most probably, you see browser caching problem.
Once file read, next time you get file content from the cache - not from network.
Simple workaround - you can add unique URL parameter like http://localhost:8080/subdir/file.txt?par=123. Changing such parameter you always get new content from the server.

Unfortunately, nocache parameter does not affect plain files access.
I will try to fix it.


Actually, how you access your files?

I checked once again - nocache set following http headers also for file access:

HTTP/1.1 200 OK
Cache-Control: no-cache, no-store, must-revalidate, private, max-age=0
Expires: 0
Pragma: no-cache
Content-Type: image/x-icon
Last-Modified: Thu, 17 Oct 2019 06:43:52 GMT
Etag: "5da80da8.32038"
Content-Length: 32038
Accept-Ranges: bytes
Date: Wed, 17 Apr 2024 11:10:09 GMT

But it responsibility of the browser to correctly process it.
Anyway - workaround with file.txt?par=<unique> should work in all cases.

P.S. Sorry for late reply - I was in 3-weeks vacation