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Learn

• Java — From syntax to object-oriented programming, collections, threads, and the JVM. See what happens inside when code runs.
• Spring — The container and dependency injection, AOP and transactions, the path a web request takes, and what Spring Boot does for you.
• JPA — What it means to store objects in tables: the persistence context, relationships, lazy loading, and when and how many queries are sent.
• Database — Table design and SQL, indexes and execution plans, transactions and locking, replication and distribution. See how data is stored and read.
• Networking — From typing an address to receiving the response: DNS, TCP, HTTP, TLS, and the machines in between.
• Security — Authentication (who you are), authorization (what you are allowed to do), web attacks and defenses, and cryptography.
• Architecture and operations — Topics for when traffic grows, when a system is split into services, and when you deploy and monitor it.