Lectures

We break down XML as a data format: how elements and the document tree are structured, why attributes and self-closing tags are needed, why spaces and line breaks become data, which rules make a document well‑formed, and how to safely insert text using entities ( &, <) and the escapeXmlText function. At the end — hands-on practice generating an XML report and the typical mistakes that make the parser refuse to work.

We break down DOM XML parsing in Kotlin on the JVM: how to turn XML into a Document tree via DocumentBuilderFactory and parse(), how to work with Element and NodeList, read attributes via getAttribute() and text via textContent, and how to write “non-crashing” code with as?, ?:, trim(), and toDoubleOrNull().

We break down how to use XPath on top of the DOM in Kotlin: why you might want it instead of “manual tree traversal,” how the XML → Document → XPath queries pipeline is structured, what evaluate modes exist (string and NODESET), how to work with NodeList, and how, in practice, to import a list of entities (example: expenses) from XML without turning the code into a mess of getElementsByTagName and item(0).

We break down why XML documents need a contract in the form of XSD: what makes well-formed XML different from schema- valid, how a schema is structured ( xs:schema, required attributes and types), and how to validate documents on the JVM using the SchemaFactory → Validator combo. We show minimal Kotlin functions, exception handling ( try/ catch), as well as typical mistakes and the limits of what XSD can do.

We break down how XSLT differs from XPath, how to think “input XML + templates → output,” and how to run a transformation on the JVM/Kotlin via a standard pipeline: TransformerFactory → Transformer → transform(...). We’ll show a minimal working example, “ XML → text” and “ XML → XML” variants, working with StreamSource/ StreamResult, plus practical tips for diagnosing errors and common pitfalls.