Display in Web Browser (display)

While OCFL objects are filesystem-based and human-readable, navigating through different versions and viewing metadata directly in the directory structure can be overwhelming. gocfl offers a built-in web viewer for this purpose.

1. The `display` Command

With the display command (alias: viewer), gocfl starts a local web server that provides a graphical interface for exploring the storage root and the objects it contains.

Basic Syntax:

gocfl display [path to storage root or object]

Workshop Example:

To view the storage root created in the workshop in the browser, we use:

gocfl --config ./gocfl/config/gocfl.toml display ./gocfl/temp/test42/

Explanation:

display: Starts the integrated web server.
./gocfl/temp/test42/: The path to the storage root.
By default, the viewer is accessible at http://localhost:8080.

2. Viewer Functions

Once the server is running and you call the address in your browser, the gocfl viewer offers the following possibilities:

Object List: Overview of all objects in the storage root (with ID and path).
Version History: Selection between the different versions of an object (e.g., v1 and v2).
File Browser: Browsing through the logical directory structure (state) of the chosen version.
Metadata Display: Direct display of technical metadata (if generated by extensions like NNNN-indexer).
Preview: Viewing images or playing audio/video files directly in the browser (supported by the NNNN-thumbnail extension).
Fixity Information: Display of checksums for each file.

3. Important Parameters

If the default port 8080 is already occupied or access is to be made from another computer, the following flags can be helpful:

--display-addr: Changes the address or port on which the server listens (e.g., :9090).
--display-external-addr: Sets the URL used for links within the viewer (important when operating behind a reverse proxy).

4. Closing the Viewer

Since the command blocks the terminal process while the server is running, the viewer can be closed at any time by pressing Ctrl+C.

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