Load SPA from cache without network connection

[Urbanus01]

Hello All,

- What version of the product are you using?

v86.0.24

- What architecture x86 or x64?

Both

- On what operating system?

Win10

- Are you using WinForms, WPF or OffScreen?

WPF

- What steps will reproduce the problem?

I faced with next issues:

SefSharp doesn't load SPA website from cache after close and open window (WPF, Cef version 86.0.24).
I try to open sites with old HTML manifest mechanizm or jakecache.js,
this issue is reproducible in both cases.
I have already set up CachePath folder, and see cache files stored on my hard disk, but looks lake that they doesn't used, if no internet connection.

public partial class MainWindow : Window
{
private readonly string CacheFolderPath = $"{Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)}\POS Software\Shell";

    public MainWindow()
    {
        CefSettings Settings = new CefSettings
        {
            CachePath = Path.Combine(CacheFolderPath, "CefSharp\\Cache")                

        };
        Settings.CefCommandLineArgs.Add("ignore-certificate-errors");

        if (Cef.IsInitialized == false)
        {
            Cef.Initialize(Settings);
        }
        CefSharpSettings.ConcurrentTaskExecution = true;
        InitializeComponent();
        var urltoLoad = DataInteractionService.GetValue(DataInteractionConstants.UrlToLoad);
      
        if (!string.IsNullOrWhiteSpace(urltoLoad))
        {
            this.GeneralChromiumWebBrowser.Address = urltoLoad;
        }
        this.GeneralChromiumWebBrowser.BrowserSettings = new BrowserSettings
        {
            LocalStorage = CefState.Enabled, WebSecurity = CefState.Disabled
           
        };

}

Could you assist, how to solve it?

[amaitland]

Does it work in Chrome when the internet is disconnected? If yes then you can try setting the browser to offline via DevTools see https://bitbucket.org/chromiumembedded/cef/issues/245/direct-control-over-online-offline-status for some background.

You can try http://cefsharp.github.io/api/86.0.x/html/M_CefSharp_DevTools_Network_NetworkClient_EmulateNetworkConditionsAsync.htm

You can try adapt the example below

using (var client = chromiumWebBrowser.GetDevToolsClient())
{
    _ = client.Network.SetUserAgentOverrideAsync("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 - Testing 123");
}

[Urbanus01]

Hello amaitland,

First of all, Thank you for your time!

Does it work in Chrome when the internet is disconnected?
Yes, it does. Please try to open this https://pos.ehopper.com/25

I have tried all tricks that you mentioned, but unfortunately, it doesn't help =( Lent me more concretize the steps for prevent misunderstanding.

1. Open this link https://pos.ehopper.com/25 on Chrome or Cef WPF application( I set CachePath for CefSettings and apply it)
2. On Dev Tool in Network tab set Offline.
3. Refresh page. For Chrome ( Cnt + R on dev tool or just enter on address line).
   For Cef WPF aplication close and open (sets same link on your code) or (I use binded hot keys commanad for
   this.GeneralChromiumWebBrowser.Address = url;
   this.GeneralChromiumWebBrowser.Load(url);
   ).
4. In Chrome everything works fine, website loaded. For Cef application I see white screen and one line with ERR_INTERNET_DISCONNECTED on Network dev tool tab.

Also I try this with HTML5 cache manifest with same results.

Best regards,
Mykhailo Dashkel

[amaitland]

You can try asking in https://magpcss.org/ceforum/viewforum.php?f=18 (CefSharp is just one of many chromium embedded framework wrappers, there's a much larger community on ceforum).

I'm now on holidays.