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Validation (validate)

A crucial advantage of OCFL is integrity assurance. With gocfl, it is possible to verify at any time whether a storage root or an individual object still complies with the specification and whether all checksums (digests) are correct.

1. The validate Command

The validate command (or the alias check) performs a deep check of the OCFL structure. It checks both the formal requirements of the specification and the consistency of the data against the inventory.

Basic Syntax:

gocfl validate [path to storage root or object]

Workshop Example:

We validate the specific object in the storage root that we created and updated in the previous steps:

gocfl --log-level INFO --config ./gocfl/config/gocfl.toml validate ./gocfl/temp/test42/ -i urn:nbn:de:gbv:42-test1

Explanation of Parameters:

• validate: The command to verify integrity.
• ./gocfl/temp/test42/: The path to the storage root.
• -i urn:nbn:de:gbv:42-test1: The specific object ID to be checked. If this ID (or the flag -i) is omitted, gocfl validates all objects found in the storage root sequentially.

2. What is checked?

During validation, gocfl performs the following steps:

1. Structure Check: Does the structure of the storage root and the objects comply with the OCFL specification (presence of markers, correct directory structure)?
2. Inventory Validation: Is the inventory.json well-formed? Are all versions present without gaps?
3. Fixity Check: Recalculates the digest for every file in the object and compares it with the value in the manifest.
4. Reference Check: Do all paths in the state point to existing files in the manifest? Are there “orphaned” files in the content folder that are not listed in any manifest?
5. Extension Check: Are the used extensions correctly configured and documented?

3. Selective Validation

If a storage root contains many objects, validation can be time-consuming. gocfl offers flags to narrow down the check:

• Only a specific object (ID):

  gocfl validate ./gocfl/temp/test42/ --object-id urn:nbn:de:gbv:42-test1
  

• Only an object at a specific path:

  gocfl validate ./gocfl/temp/test42/ --object-path 1f7/d28/1ac/1f7d281acc...
  

4. Result of the Validation

When the validation is complete, gocfl outputs a summary. It is important to distinguish between errors and warnings.

Example Output from the Workshop:

{"level":"info","time":"2026-03-14T17:13:59Z","message":"loading configuration from "}
2026-03-14T17:13:59Z INF validating '/home/ocfl/gocfl/temp/test42' host=gocfl timestamp="..."
2026-03-14T17:13:59Z WRN extension NNNN-gocfl-extension-manager is not registered ... validationErrorCode=W013 validationErrorMessage="‘In an OCFL Object, extension sub-directories SHOULD be named according to a registered extension name.’"
2026-03-14T17:13:59Z WRN extension NNNN-content-subpath is not registered ... validationErrorCode=W013
...
2026-03-14T17:13:59Z INF object 'urn:nbn:de:gbv:42-test1' with object version '1.1' found host=gocfl task=checker ...

[extension NNNN-content-subpath is not registered]
   #W013 - ‘In an OCFL Object, extension sub-directories SHOULD be named according to a registered extension name.’ []

...

no errors found
2026-03-14T17:14:00Z INF Duration: 221.808179ms host=gocfl ...

Interpretation of the Result:

1. Warnings (W-Codes, e.g., W013):
   • In our example, we see several warnings with the code W013.
   • These refer to the fact that the extensions used (e.g., NNNN-content-subpath) are not officially registered with the OCFL community (hence the NNNN- prefix).
   • According to the OCFL specification, extensions should be registered, but it is allowed to use custom or community extensions.
   • A warning does not mean the object is invalid.
2. Errors (E-Codes):
   • Errors (e.g., E001, E066) would indicate a violation of the OCFL core specification (MUST requirements).
   • An object with errors is considered invalid and must be repaired (e.g., in case of checksum errors).
3. Conclusion:
   • The message “no errors found” at the end confirms that the object is technically correct and integer despite the warnings. All files are present and the checksums match the inventory.

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