StephanHerrmann A Precise Model for Contextual Roles: The Programming Language ObjectTeams/Java Applied Ontology 2 181-207 2007 MatthiasQuasthoff HaraldSack ChristophMeinel Who Reads and Writes the Social Web? A Security Architecture for Web 2.0 Applications 2008 The World Wide Web has changed during the last decade. The so-called Web 2.0 enables inexperienced users to become worldwide publishers. Most often these users also don't have any idea about how to protect their own user-generated content or how to trust in content provided by aggregated and syndicated services. Public Key Infrastructures, digital signatures, and reputation services are well established but hard to understand and to handle for the layperson. We propose an efficient and user-friendly security architecture based on the popular tagging paradigm that connects user-defined tags with security policies, rules, and social network information to ensure access control, data integrity, and confidence also in derived and syndicated data. ArianTreffer Object Teams 2008