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Creating and Adding Objects

In this step, we add our first object to the OCFL storage root. The add command is used to transfer new content into the archive.

1. The add Command

With gocfl add, files or directories can be stored as an OCFL object.

Basic Syntax:

gocfl add /path/to/data -i "object-id"

Workshop Example:

In our workshop scenario, we add the content from payload1/ to the previously initialized storage root test42/:

gocfl --log-level DEBUG --config ./gocfl/config/gocfl.toml add ./gocfl/temp/test42/ ./gocfl/testdata/payload1/ --ext-NNNN-metafile-source ./gocfl/testdata/info.json -i urn:nbn:de:gbv:42-test1

Explanation of Parameters:

• --log-level DEBUG: Shows detailed information during the process.
• --config ./gocfl/config/gocfl.toml: Uses our central configuration file. Predefined values from the [Add] section of the gocfl.toml are applied (see below).
• add: The command to add/create an object.
• ./gocfl/temp/test42/: The path to the storage root (our target directory).
• ./gocfl/testdata/payload1/: The source path of the data to be archived.
• --ext-NNNN-metafile-source ./gocfl/testdata/info.json: A specific parameter for the NNNN-metafile extension to include an external metadata file.
• -i urn:nbn:de:gbv:42-test1: The unique object ID.

2. Configuration in gocfl.toml

The central configuration file gocfl.toml defines default values in the [Add] section, which apply to every add operation unless overridden by command-line parameters:

[Add]
# Default commit message
Message="initial commit"
# Hashing algorithm to use
Digest="sha512"
# Additional fixity hashes to be calculated
Fixity=["sha256", "sha1", "md5"]
# Path to default object extensions
ObjectExtensions="/home/ocfl/gocfl/config/extensions/object"
# Default data area for extraction
DefaultArea="content"

[Add.User]
# Default username for the OCFL inventory
Name="User OCFL"
# Default email address
Address="mailto:ocfl.user@unibas.ch"

3. What Happens During Adding?

1. Hashing: gocfl calculates the checksums (default SHA-512) of all files. Note: In OCFL, only sha512 and sha256 are allowed as primary algorithms by default. The use of additional algorithms (e.g., md5, sha1) in the Fixity section is enabled by the extension 0009-digest-algorithms.
2. Layout: The object ID is translated into a physical path according to the configured storage layout extension (e.g., 0004-hashed-n-tuple-storage-layout).
3. Structure: Within the object directory, the OCFL structure is created (inventory, v1/content/).
4. Extensions: All configured object extensions are triggered (e.g., for metadata extraction). Various data areas are managed by the NNNN-content-subpath extension. A detailed overview of the extensions used can be found in the chapter OCFL Object Extensions.

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