Handler

![code_architecture] (https://raw.githubusercontent.com/mementoweb/timegate/master/doc/code_architecture.png)

A Handler is an API-specific piece of code that plugs into the TimeGate to match any kind of API. The handlers are kept as simple as possible. They require to have only the following:

• A handler must extend the Handler base-class, and it must be the only python class to do so.
• Implement the get_all_mementos(self, uri_r) function. This function is called by the TimeGate to retrieve the history an original resource uri_r. The return value must be a list of pairs: [(uri_m1, date1), (uri_m2, date2), ...] . Each pair (uri_m, date) contains the URI of an archived version of R uri_m, and the date at which it was archived date. All URI fields must be strings All Date fields must be strings formatted as the ISO, date format
• If the API cannot return the entire history for a resource, the handler must implement the get_memento(self, uri_r, date) function. This function will be called by the TimeGate to retrieve the best Memento for uri_ at the date date. In this case, the return value will contain only one pair: (uri_m, date) which is the best memento that the handler could provide taking into account the limits of the API.

Handlers examples are provided for several APIs:

• GitHub.com
• arXiv.org
• wikipedia.org
• awoiaf.westeros.org

Other scraping Handlers examples are provided for resources without any API.