Repository namespaces

Each Daisy repository (since Daisy 2.0) has a namespace. The documents created in that repository will by default belong to that namespace. The ID of a document is the combination of a numeric sequence and the namespace, for example:

2583-AWAN

Each repository server is responsible for maintaining the sequence number for the documents of their namespace. When a document is created with a foreign namespace (a namespace from another repository server), the sequence ID needs to be supplied, since it is assumed that another repository server is responsible for that namespace. On the other hand, when a document is created in the namespace of the repository server itself, then a sequence ID cannot be supplied, as the repository server itself is then responsible for assigning the sequence ID.

A Daisy repository server doesn't really care whether foreign namespaces are really associated with other repository servers. The namespace could also come from an external application that creates documents (and maintains its own sequence counter), or it could come from a manually created 'export' that is imported using the import tool. So for foreign namespaces, it just assumes someone else is responsible for assigning unique sequence numbers.

Namespace name

A namespace can be up to 200 characters and contain the characters a-z, A-Z, 0-9 and _ (underscore). The dot character is not allowed to avoid confusion with file name extensions (as the document ID will often be used in URLs), and the dash character is not allowed to avoid confusion with the separator between the sequence number and the namespace.

The namespace name is typically a short string. This approach has been choosen to keep the document IDs short and readable. But as a consequence, it requires some care to avoid conflicting namespaces within an organisation, and between organisations there's no control whatsoever.

If you want to avoid the possibilities of conflicts and don't care about the readability, it is always possible to use a longer string. For example, a registered domain name or a random generated string (GUID). However, in general we would recommend to stick with a short name.

The repository server installation tool gives some recommendations on namespace naming.

Namespace purpose

Namespaces have little purpose as long as documents are not exchanged between repositories. The main purpose of namespaces it to allow import/export (replication) of documents between repositories. If there wouldn't be namespacess, the document IDs between the repositories would not be unique and hence there would be conflicts. For example, in both repositories there might be a document with ID 55, though these would be different documents. It would of course be possible to assign new IDs to documents upon import, but then the identity of the original document would be lost, which would make subsequent 'update' imports difficult, and also requires updating links in all document content (which would mean the import tool has to understand the document formats).

Namespace fingerprints

For each namespace, there is an associated namespace fingerprint. Since namespaces will usually be short strings, and since there might be people who choose the same namespace or simply used the proposed default (DSY), some additional verification is needed to assure that two namespaces are really the same. For this purpose, each namespace name is associated with a fingerprint. The namespace fingerprint is typically a longer random generated string.

The repository server keeps a table of the namespaces used in the repository and their corresponding fingerprints (these are the namespaces that are said to be registered in the repository). The registered namespace are viewable through the administration screen of the Daisy Wiki, which also allows unregistering unused namespaces.

For export/import, namespace fingerprint information is included in the export, so that it can be verified upon import.

Namespacing of non-document entities

At the time of this writing, only documents are namespaced. Thus other entities, like the document, part and field types are not in a namespace. The export/import tools assume that if the name corresponds, they are the same.