Browsium Blog

Let’s Get Technical – Understanding the Sandbox Feature of UniBrows

Posted by: Browsium Posted date:

One of the features that UniBrows has at its disposal to help maintain maximum compatibility with web sites is the idea of a settings sandbox.

When the browser session is closed, the sandbox is destroyed – returning all disk space & resources used by the UniBrows browsing session (like all the cached files) back to the operating system. It helps to guarantee isolation between changes made inside any UniBrows sessions from affecting anything in the native default Internet Explorer browser. There are other benefits including security, performance and privacy that are also gained by storing all settings in a sandbox.

This table shows what settings are written to and read from what locations depending on whether the UniBrows sandbox is enabled or disabled:

Sandbox setting Read (File System & Registry) Write (File System & Registry)
Sandbox ON
  • Values that exist on disk
  • Changes that exist in memory
  • Changes written to memory
Sandbox OFF
  • Values that exist on disk
  • Changes written to disk

Essentially, with the sandbox enabled, UniBrows browsing sessions will read real settings (or from temporarily changed settings in memory) and will write temporary copies of settings (including local Internet cached files) to a temporary storage location that’s cleaned up (destroyed) after the UniBrows session ends.

The sandbox is ideal most of the time, but there can be instance where applications may not work as intended when the sandbox enabled.

One example is a web application that has to download a lot of information the first time a user connects to the site. With the sandbox enabled, every connection will act like the first connection, which would force the user to re-download the content every time they visit the site. For some applications, the download is sizable and the user delay is long enough that, for that profile, UniBrows administrators may want to disable the sandbox.

Another example is in cases where the IE6 browser interacts with a locally-installed program through file system objects (like image viewers). If the UniBrows sandbox is on, those files may be saved to a location that the 3rd party program does not know about, and as a result the application may appear to fail. In this case as well, we encourage the UniBrows administrator to consider disabling the UniBrows sandbox to restore maximum application compatibility.

The sandbox settings is a per-profile setting, so if you have several different applications managed by profiles but only one needs to disable the sandbox, you can do so without affecting the behavior of other UniBrows-rendered sites.

Where to find the setting

The checkbox to toggle this setting may be found in the Profile / Settings tab of the UniBrows Configuration Manager, as shown here:


By default, the sandbox feature is enabled for all profiles, but can be disabled for any profile at the discretion of the UniBrows administrator. The sandbox feature is available in UniBrows version 1.0.3 and later.


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