Glossary

Identity Map

Keeps one representation of an identity within a persistence scope. It is neither a global cache nor freshness beyond that session.

Image digest

A cryptographic digest of an image manifest in a registry. Identifies a specific artifact; a local Docker image ID identifies a different object and is not interchangeable.

Immutability

An immutable object does not change state after construction. A fixed reference or read-only list does not guarantee immutability of nested objects.

Inbox

A durable record of handled messages or identifiers at the recipient. It must coordinate with the business-effect transaction so duplicates do not repeat the effect.

Infrastructure as code

IaC

Infrastructure as Code

A versioned infrastructure description that tools can review and reproduce. Define one resource owner and inspect change plans and drift.

Ingress

Incoming traffic at a specified boundary. Kubernetes Ingress is also a specific HTTP/HTTPS routing resource requiring a controller. It is not all incoming traffic or a firewall.

Input/output

I/O

Input/Output

Data exchange with the program’s environment, such as networks, files or databases. I/O waiting and CPU computation require different diagnosis and optimization strategies.

Instant

A specific point in time independent of local date and timezone. Java Instant suits an expiry deadline. A timezone is needed for local presentation, not for comparing instants.

Integration test

Checks collaboration between real components, such as a use case and PostgreSQL. For transactions inspect committed state, not merely absence of exceptions.

Interactive console

REPL

Read–Eval–Print Loop

A loop reading input, evaluating it and printing results. A framework console can invoke real services and data.

Interface

A contract of available operations separated from implementation. Use it for meaningful boundaries or alternatives, not mechanically for every class.

Internet Assigned Numbers Authority

IANA

Internet Assigned Numbers Authority

An organization also maintaining the time-zone database. Europe/Warsaw identifies time-dependent rules, not a fixed UTC offset.

Internet Gateway

IGW

Internet Gateway

A component connecting a VPC to the internet. Typical IPv4 access also requires a suitable route, public addressing and security rules.

Invariant

A rule that must hold after every allowed operation, such as no overlapping active reservations for one item. Test it after failures and under concurrency too.

IP address

IP

Internet Protocol

An address used to route IP-network traffic. It is not durable user identity or proof of trust; NAT, proxies and infrastructure changes affect the observed address.

ISP

ISP

Interface Segregation Principle

A client depends only on operations it needs. A price calculator should not need messaging or migration methods.

Iterator

Supplies successive elements without exposing collection structure. Lazy iteration may hold resources or execute queries; it does not automatically guarantee constant memory use.

Java

A statically typed language used as this project’s main JVM reference. Language version, libraries and threading model are separate decisions verified through tests.

Java Archive

JAR

Java Archive

A format packaging JVM classes and resources. A JAR does not necessarily contain every dependency or runtime configuration.

Java Platform Module System

JPMS

Java Platform Module System

The Java module system describing dependencies and exported packages. It does not replace Gradle or automatically define domain boundaries.

JAVA_HOME

An environment variable name, not an acronym.

An environment variable pointing to a Java installation used by selected tools. The terminal java command also depends on PATH; compare both with the IDE.

JavaScript

JS

JavaScript

A language running in browsers and runtimes such as Node.js. Numbers, asynchrony and null/undefined semantics require deliberate input modelling.

JDBC

JDBC

Java Database Connectivity

Java’s interface to relational databases through a driver. Connections and transactions need clear ownership; a connection pool is a bounded resource.

JDK

JDK

Java Development Kit

A toolkit for building and running JVM programs, including a compiler. The JDK running Gradle and the compilation toolchain may differ.

JDK Enhancement Proposal

JEP

JDK Enhancement Proposal

An OpenJDK proposal describing a Java platform change and its motivation. Proposal status does not prove availability in your JDK; check the release and preview requirements.

JDWP

JDWP

Java Debug Wire Protocol

The debugger connection protocol for a running JVM. Bind locally for the exercise; waiting before main is intentional when suspend is enabled.

JFR

JFR

JDK Flight Recorder

A JVM event recorder useful for CPU, lock, allocation and latency diagnosis. Interpret recordings together with a hypothesis and experiment conditions.

Job / CronJob

A Job drives a task to completion; a CronJob creates Jobs on a schedule. Retries or overlapping executions require idempotency and an explicit concurrency policy.

JOIN

JOIN, LEFT JOIN and INNER JOIN are SQL operation names, not abbreviations.

Combining data through relationships in SQL. Check result cardinality and missing matches; one-to-many relationships can multiply rows.

jOOQ

jOOQ

Java Object Oriented Querying

A JVM library for SQL, including a typed DSL and schema-based code generation. Types assist compilation but do not prove transaction correctness or query performance.