So in the Sitecore site, in Data/Submit Queue, there is a file without an extension that is representing the content of the Submit Queue.
If you try viewing it as a text file, it shows some content, but there is some strange characters in the mix.
So, has someone made an application to view this file? Is it suppose to be in a specific format that should opened with an application able to view that format?
Extra info: Sitecore 8.0, no there is nothing about it in the control panel or in sitecore/admin.
This file contains the analytics data that was not flushed to the Mongo database.
In case xDB collection server is unavailable, Sitecore would/must handle this situation correctly. There is a special 'Submit Queue' mechanism introduced that flushes captured data to local server hard drive ( 'Data\Submit Queue' folder by default ) in case xDB is not available.
When xDB is up again, a background worker would submit the data saved on disk, so no data is lost.
As a quick suggestion on this I recommend you to check whether your MongoDB server is available for your Sitecore instance. Once it becomes available, all data from the file should be flushed to the xDB.
The submit queue file stores serialized values as follows: first value - number of entities, second value - position of the next entity, which must be submitted to xDB, the next values contain serialized analytics data.
The submit queue is processed using this class: Sitecore.Analytics.Data.DataAccess.SubmitQueue.FileSubmitQueue
If you want to debug to see how is processed decompile the class and create your own class and replace in Sitecore.Analytics.Tracking.confing
<submitQueue>
<queue type="Sitecore.Analytics.Data.DataAccess.SubmitQueue.FileSubmitQueue, Sitecore.Analytics" singleInstance="true" />
</submitQueue>