Suffix Passthrough

Suffix Passthrough (SPT) is a feature that lets you add any suffix to an identifier, and when a user selects (“clicks on”) the identifier, the suffix is added to the end of the identifier’s location (target) URL. It dramatically reduces the maintenance burden by permitting one identifier to stand in for many identifiers.

The transformation of an identifier into its final location URL is done by a web server called a resolver, and the transformation is called resolution. Typically a web browser uses the resolver to find the final location URL, which it then displays in its location bar. The SPT feature can only be used when ARKs are served by local resolvers that implement it. For example, it is available to all institutions (and the general public interacting with their ARKs) who get resolver services from EZID or from services built on the arklet-frick code base. This includes the Smithsonian Institution, the Frick Collection, and the WACREN network.

Basically, Suffix Passthrough makes every ARK the root of its own “namespace”. Any user-added suffix, which is a common way to form sub-object identifiers, will be passed through to the registered target object. For example, a dataset with a million component parts and just this one “ancestor” ARK,

https://n2t.net/ark:12345/x98765

would effectively allow access to a million ARKs, but only require you to manage the ancestor ARK. Those sub-object ARKs might look like: :

https://n2t.net/ark:12345/x98765/study1/location1/day1.cs
https://n2t.net/ark:12345/x98765/study1/location3/day19.cs
 ...
https://n2t.net/ark:12345/x98765/study92/location18/day96.xlsx

When a user clicks on one of those ARKs, it is submitted to N2T, which sees that it is forwarded to the local resolver. Failing to find it stored, the local resolver scans scans starting from the end of the user-supplied ARK string and stops at the first ancestor ARK that is stored (registered) in the resolver.

The part that was scanned over, stretching from the first registered ancestor ARK to the end of the original string, comprises the suffix.

https://n2t.net/ark:12345/x98765/study92/location18/day96.xlsx
\______________________________/\____________________________/
          ancestor ARK                      suffix

Then it redirects the user’s browser to the ancestor’s target URL, appending the suffix that it scanned. So if the ancestor ARK’s target was, :

https://n2t.net/ark:12345/x98765 --> https://datazoo.example.com/carbon288
\______________________________/     \___________________________________/
       ancestor ARK                        ancestor ARK's target URL

the user would be (hypothetically) redirected to :

https://datazoo.example.com/carbon288/study92/location18/day96.xlsx
\___________________________________/\____________________________/
       ancestor's target URL                    suffix

Note that SPT is only useful when the target server can respond to the suffixes it receives. For example, you would not instruct users how to add suffixes to the above ARK unless the target server was prepared to provide access to its one million sub-objects. Fortunately, SPT is easy to illustrate in some cases, such as when the target server extends resource names with query strings or ordinary URL paths.

Rule: if identifier A has target T, suffix passthrough means the extended identifier A/X has target T/X.

Using more words, for an identifier A stored in N2T that has the target URL T, if you add a suffix X to A and resolve (eg, click on) the URL A/X, you will be redirected to the URL T/X.

Some limitations and exceptions apply. For example, scanning stops when the NAAN (the number directly after the “ark:”) is reached.

Suffix Passthrough Examples

You can see SPT in action by clicking on the extended ARKs below. These are “ARKs” (for illustration purposes only, not long-term stable) that are not stored in the local resolver, but are formed by adding a suffix to an ARK that is stored.

Example 1. One stored ARK standing in for several CDL service page “ARKs”.

Stored: ark:12345/fk1234
Its target URL: https://www.cdlib.org/services
An extended ARK: https://n2t.net/ark:12345/fk1234/uc3/ezid/

Example 2. One stored ARK standing in for any number of Wikipedia article “ARKs”.

Stored: ark:12345/fk1235
Its target URL: https://en.wikipedia.org/wiki
An extended ARK: https://n2t.net/ark:12345/fk1235/Persistent_identifier

Example 3. One stored ARK standing in for any number of internet search “ARKs”.

Stored: ark:12345/fk3
Its target URL: https://www.google.com/#q=
Extended ARK: https://n2t.net/ark:12345/fk3pqrst

You can experiment easily by pasting this stored ARK, :

https://n2t.net/ark:12345/fk3

into your browser’s location field and appending (no spaces) a “search term” suffix of your choice.