Appendix C. Enumerator API
DX Content Router provides a public HTTP 1.1 server interface component as part of the DX
Content Router Publisher service. The purpose of the HTTP interface is to enable a simple
standards based approach for building "plug-in like" DX Storage internal and 3rd party applications
that require some form of object enumeration. The DX Content Router Replicator service utilizes
this interface extensively to provide reliable object replication across Wide Area Networks. Some
other applications might include 3rd party object replication and/or backup applications, object
index/search engines, metadata query engines and virus scan applications. The base URL for any
enumerator is:
http://<publisherHost>:<publicationServerPort>/
C.1. Enumerator Types
Enumerator types are defined based on the type of data that should be returned with the response.
The default type is a Metadata enumerator. The list of supported types is:
• Metadata Enumerator: Metadata enumerators return the UUIDs and all associated metadata
for objects that match the specified filters. In the 2.1 and later releases, Metadata enumeration
includes all creates and updates regardless of subsequent deletes. Every event associated
with a mutable object (POST, COPY, APPEND, PUT, DELETE, etc) is included as a separate
enumeration item. In DX Content Router 2.2, metadata enumerators include metadata for both
named and unnamed DX Storage objects.
• UUID Enumerator: UUID enumerators return the UUIDs for all objects that match the specified
filters.
UUID enumeration includes the UUIDs for create events of immutable objects unless a
subsequent delete event has been registered by the Publisher for the same object. For mutable
objects, the alias UUIDs for creates and updates are included regardless of subsequent deletes in
order to ensure proper processing of all object revisions across different nodes and clusters. This
will result in the same alias UUID being enumerated multiple times if there are update or delete
events.
Only unnamed DX Storage objects are returned by the UUID enumerator in DX Content Router
2.2.
• Event Enumerator: Event enumerators return the UUIDs for objects that match the specified
filters as well as the last event associated with the UUID (create, update or delete). Only unnamed
DX Storage objects are returned by the Event enumerator in DX Content Router 2.2.
Note
Delete events are considered to match all channels and are sent to all subscribers. This
ensures delete events transmitted via a previous rule version are known to be deleted
even if they no longer match the current rules.
For a complete discussion of different DX Storage object types, including named, unnamed and
alias objects, please refer to the DX Storage Application Guide.
C.2. Enumerator Start
The Enumeration Start command instantiates an object enumerator for a given channel in Publisher,
and returns a unique identifier for this enumerator. The format of the request is as follows:
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