OpenID is a decentralized authentication protocol that makes it easier for users to access resources in your Java Web applications. In this first half of a two-part article, you'll learn about the OpenID Authentication Specification and walk through the steps of incorporating it into a sample Java application. Rather than implement the OpenID Authentication specification by hand, author J. Steven Perry uses the openid4java library and a popular OpenID provider, myOpenID, to create a safe and reliable registration process for a Java application written in Wicket.