- iOS – Networking with URLSession
One type that performs requests, and everything else describing them. An Endpoint as inert data so routes are testable without a socket, async/await over URLSession, Codable and the decoding failures that only happen in production, and configuration that comes from the build rather than a constant.
- Spring Study Guide – Web Layer
Spring MVC end to end. What the DispatcherServlet does with a request, the six delegates it hands off to, how a URL reaches a method, the controller method parameters and return types worth knowing, the Model and where the view gets it, view resolution, the web scopes, and why the whole design is testable without a servlet container.
- Regex
A regular expression describes a pattern of text. Java's support lives in java.util.regex , and the hardest part is not the syntax — it is knowing when a regex is the right tool and keeping the ones you write readable. The three ways in Compile the pattern once if it is used more than occasionally.…
- Backend Dev – Authentication, Authorization and Security
Who are you, and are you allowed to do that — two different questions that beginners merge into one. Password storage that survives a database leak, sessions versus stateless JWT and the trade you are making, OAuth2 login, checking permissions on the object and not just the endpoint, and the handful of attacks worth knowing by name.
- Tries
A prefix tree: one node per character, words spelled out along the paths. Why it is the wrong choice for exact lookup — a HashSet is simpler and faster — and the right one for autocomplete and every other prefix question a set cannot answer.