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Background association requests
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###############################
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This document describes how to make signing in with OpenID faster for
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users of your application by never making the users wait for an
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association to be made, but using associations when they're
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available. Most OpenID libraries and applications attempt to make
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associations during the discovery phase of the OpenID authentication
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request. Because association requests may have to do Diffie-Hellman
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key exchange, which is time consuming. Even if Diffie-Hellman key
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exchange is not used, the user still needs to wait for the association
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Setting up your application to make associations in the background
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==================================================================
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When making associations background, there are two components that
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need access to the OpenID association store: the consumer application
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and the background association fetcher. The consumer needs to be set
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up to record the server URL for any request for which an association
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does not exist or is expired instead of making a new association. The
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background fetcher looks at the server URL queue and makes
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associations for any server URLs that need them. After the
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associations are made, the consumer will use them until they expire
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again. While associations are expired or missing, the consumer will
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use stateless mode to complete authentications with the servers that
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The OpenID server endpoint URL queue
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You will have to set up a conduit between the consumer and the
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background association fetcher so that the background association
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fetcher knows what servers need associations. The background
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association fetcher will not fetch associations for servers that
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already have them, so the queue does not have to be very smart. It
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could be as simple as a file to which the server URLs are
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appended. Either way, the queue needs to be write-able by the consumer
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and readable by the background fetcher.
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Configuring the consumer
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Create a subclass of ``GenericConsumer`` that overrides
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``_negotiateAssociation`` so that it just records the server URL that
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needs an association::
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from openid.consumer.consumer import GenericConsumer, Consumer
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class LazyAssociationConsumer(GenericConsumer):
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needs_assoc_file = None
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def _negotiateAssociation(self, endpoint):
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# Do whatever you need to do here to send the server_url to
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# the queue. This example just appends it to a file.
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self.needs_assoc_file.write(endpoint.server_url + '\n')
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self.needs_assoc_file.flush()
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You could also store the whole endpoint object. When you instantiate
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the consumer, pass this generic consumer class to the controlling
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return Consumer(session, store, consumer_class=LazyAssociationConsumer)
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The background association fetcher
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The background association fetcher is just a script that should be
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added to ``cron`` or triggered periodically. If you are ambitious, you
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could make the background fetcher listen for inserts into the queue.
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The background fetcher needs to do something similar to the following::
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def refresh(consumer, endpoint):
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if consumer.store.getAssociation(endpoint.server_url):
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logging.info("We don't need to associate with %r", endpoint.server_url)
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logging.info("Associating with %r", endpoint.server_url)
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assoc = consumer._negotiateAssociation(endpoint)
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elapsed = time.time() - now
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logging.info('(%0.2f seconds) Associated with %r', elapsed,
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consumer.store.storeAssociation(endpoint.server_url, assoc)
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logging.error('Failed to make an association with %r',
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The code in this example logs the amount of time that the association
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request took. This is time that the user would have been waiting. The
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``consumer`` in this example is a standard consumer, not the
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``LazyAssociationConsumer`` that was defined in the section
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above. This is important, because the lazy consumer above will not
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actually make any associations.
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background-associations.txt
