Permalink
Fetching contributors…
Cannot retrieve contributors at this time
109 lines (79 sloc) 4.74 KB

Use Cases

Definitions

A TwitterUser in SFM is the entity used to collect tweets tweeted by the corresponding account in Twitter.

The fundamental, unique, unchanging identifier for a Twitter account is its numeric UID. The owner of a Twitter account might change the account's name, but the UID will never change.

Each TwitterUser is intended to map one-to-one to a Twitter account.

Given the rules above, we can derive two rules:

  • A TwitterUser account should never be associated with tweets from more than one UID.
  • A TwitterUser account's UID should never change.

Lifecycle of a TwitterUser

A TwitterUser in SFM exists in one of three states:

  • Nonexistence (Pre-creation/Post-deletion)
  • Active - SFM will attempt to collect new tweets for this TwitterUser, every time the user_timeline script is run.
  • Inactive - The TwitterUser is still in SFM, but no new tweets will be collected while the TwitterUser is inactive.

An account in Twitter exists in one of four states:

  • Pre-creation
  • Active/Public - Tweets are visibile to anyone
  • Active/Protected - Tweets are only visible to this account's Twitter followers
  • Deactivated/Deleted - If an owner deactivates a Twitter account, Twitter places it on a queue to be permanently deleted after 30 days.

State Transitions

TwitterUser Creation - The SFM user provides the username of the Twitter account to map to this SFM TwitterUser. SFM looks up the Twitter account's UID by the username provided. If:

  • the username matches a Twitter account's username, and
  • the Twitter account's UID is not already associated with any TwitterUser

then SFM will create the TwitterUser. The SFM user may create the new TwitterUser as either Active or Inactive.

If the name does not match any Twitter account OR the UID is already associated with a TwitterUser, then SFM will not create the TwitterUser, even an in Inactive state.

Inactivation of Active TwitterUser - An SFM user marks an Active TwitterUser as Inactive. This transition is always allowed. Inactive TwitterUsers are still shown on the SFM page listing users, and CSV extracts

Activation of Inactive TwitterUser - An SFM user marks an Inactive TwitterUser as Active. SFM looks up the corresponding Twitter account by the UID of the TwitterUser. If the UID is valid, it updates the TwitterUser's name if differs from the current name of the Twitter account, and saves the TwitterUser as Active. If the UID is not found, which may occur if the Twitter account has been deactivated, then SFM does not allow the TwitterUser to be saved as Active.

Deletion of a TwitterUser - An SFM administrative user deletes a TwitterUser. This is always allowed. However, it is important to note that all TwitterItems associated with this TwitterUser will also be deleted.

Name Change - What if the owner of a Twitter account changes the name of the account? If the TwitterUser in SFM was created to collect tweets from this Twitter account, it should continue to do so, since the UID never changes. However, the name of the TwitterUser may temporarily still show the old name of the Twitter account. If a cron job has been set up to run update_usernames, then the name of the TwitterUser will automatically be updated to match the new Twitter account name the next time update_username is run. When update_username observes a name change, the old name will be appended to the TwitterUser's former_names, along with the date and time that the change was detected by update_usernames. As an example, if a Twitter account named NYTimes was then changed to NewYorkTimes, then the update_usernames script would update the name of the TwitterUser, and would also append to former_names so it might have a value like {"Thu Jan 16 13:48:56 2014": "NYTimes"}

Twitter Account Goes Protected - What if the owner of a Twitter account marks the account as protected?

If the TWITTER_DEFAULT_USERNAME configured in local_settings.py is a Twitter account which is following the protected Twitter account in question, then SFM will continue to be able to download tweets from that account.

If this is not the case, then user_timeline jobs will encounter errors when attempting to retrieve new tweets for the account. These errors will be recorded in the TwitterUserTimelineErrors table.

Twitter Account Deletion - What if the owner of a Twitter account deletes the account?

If the owner of a Twitter account deletes the account and there is an active TwitterUser mapped to the account, then user_timeline jobs will encounter errors when attempting to retrieve new tweets for the account. These errors will be recorded in the TwitterUserTimelineErrors table.