Design Pattern of the Week: Cookies

This post is part of a series on mobile user interface design patterns, excerpted from Designing the Mobile User Experience, John Wiley & Sons, 2007. This last set of patterns will address application management design for mobile applications.

Cookies are a popular method of identifying users and storing key data locally. Unfortunately cookie support varies across devices and carriers.

Design

Determine whether each cookie's function can be fully or partially accomplished through the techniques below, or other techniques. If a large portion of the site has an unacceptable user experience after reducing cookie use to its minimum, then perform a cookie test on all possible site entry pages. If the cookie can not be read on the next page, advise the user of the problem. Most users can download a browser to their phone; Opera Mini runs on all Java ME devices and supports cookies well.

One simple technique is to add user identification data to the URL string and then having the user bookmark the URL string with ID. If worried about users sharing the identity-specific URL, add function to the site for the user to share the site easily; this will prevent users from being interested in the extra steps necessary to copy and paste URLs into other applications.

Password information obviously should not be encoded in a URL, but many applications only need password verification for a small subset of their application. Delaying the demand for the password, then allowing that user access to password-protected information for a short time as determined by your server, can bypass much of the password problem.

Applicable Devices and Platforms

Browsers.

When Used

Use for web applications when the universe of browsers is not controlled or otherwise unknown.

Rationale

Some users may have cookies disabled. Other users may have cookies enabled, but their carrier or device may expunge cookies. Users who have to enter a user name and password two to three times per session of using email will quickly stop using the service.