Offline browsing - The Polipo Manual
Description: The Polipo Manual

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### 3.5 Offline browsing

In an ideal world, all machines would have perfect connectivity to the network at all times and servers would never crash. In the real world, the values of the variables `proxyOffline` and `relaxTransparency` can be used to moderate Polipo's eagerness to contact remote machines.

Setting `proxyOffline` to `true`, prevents Polipo from contacting remote servers, no matter what. This setting is suitable when you have no network connection whatsoever.

If `proxyOffline` is false, Polipo's behaviour is controlled by the variable `relaxTransparency`. If `relaxTransparency` is `false` (the default), all stale instances are validated (see Cache transparency), and failures to connect are reported to the client. This is the default mode of operation of most other proxies, and the least likely to surprise the user.

If `relaxTransparency` is `maybe`, all stale instances are still validated, but a failure to connect is only reported as an error if no data is available in the cache. If a connection fails and stale data is available, it is served to the client with a suitable HTTP/1.1 ``Warning`' header. Current user-agents do not provide visible indication of such warnings, however, and this setting will typically cause the browser to display stale data with no indication that anything went wrong. This setting is useful when you are consulting a live web site but don't want to be bothered with failed revalidations.

If `relaxTransparency` is `true`, missing data is fetched from remote servers, but stale data are unconditionally served with no validation. Client-side ``Cache-Control`' directives are still honoured, which means that you can force an end-to-end revalidation from the browser's interface (typically by shift-clicking on “reload”). This setting is useful if you have very bad network connectivity or are consulting a very slow web site or one that provides wrong cache control information1 and are willing to manually revalidate pages that you suspect are stale.

#### Footnotes

[1] `www.microsoft.com` comes to mind.