The DMS provides options to access, i.e. read/write/create documents in your DMS directly. Most operations work through the API that the Nuxeo backend provides.
Please note that the below information is given as is with no liability taken by PI or Patrix. Do not proceed to use the below information against your repository unless you are well aware of what you do.
Accessing an existing document to open for editing/saving back to system
There is an option to post a URL to the DMS server which will invoke DocIntegrate to download the document and open it using the default document handler for that type. Once saved/closed, the document will be uploaded back to the DMS server with a new version for the document being created (this is the standard CaseBrowser behaviour).
Note: The behaviour of DocIntegrate is influenced by the <editableFileTypes> key in the settings.xml file in /Workspace/Settings/ of your repository.