Khalid A. Mughal is associate professor (emeritus) in the Department of Informatics, University of Bergen, Norway. During his extensive career, he has designed and implemented many courses on Java, object-oriented system development, web application development, software security, and compiler techniques. He has also given seminars for the IT industry. He is the principal author of several books on Java. Vasily A. Strelnikov is a senior principal OCI solutions specialist at Oracle. Strelnikov's specialties are large-scale system design and integration using Java. He has created training courses for Java and Java EE. He co-created the OCP certification exam and has developed official Oracle University training video for it.