Glossary

DIP

DIP

Dependency Inversion Principle

Use-case logic depends on its contract, implemented by a technical detail. DI supplies objects; DI alone does not invert dependency direction.

Discriminated union

A union of variants sharing a discriminating field such as kind. Checking it narrows the type; the type annotation alone does not validate received JSON.

Django and DRF

DRF

Django REST Framework

Django provides broad application tooling; DRF supports API development. Admin and serializer use still require permission and data-contract checks.

DNS

DNS

Domain Name System

A system resolving names to records such as service addresses. Caching and expiry affect changes; a valid DNS answer does not prove application readiness.

A database name resolves to an address, but network rules or certificate errors may still block the connection.

Docker

Tools for building images and running containers. An image is an artifact and a container a configured process; durable data needs suitable storage outside its writable layer.

Docker Desktop

A desktop application providing a Docker environment, including a container engine and tools. On macOS/Windows it uses a Linux layer. Its built-in Kubernetes is optional and does not automatically replace a lesson’s kind cluster.

Doctrine ORM

A PHP ORM tracking entities in a Unit of Work and synchronizing changes on flush. Registering an object with persist is not an immediate INSERT.

Domain-specific language

DSL

Domain-Specific Language

A language tailored to a domain, such as SQL construction or configuration. Convenient syntax should not obscure effects or guarantee boundaries.

dotenv

A loader reading key/value entries from an .env file into process configuration. A file alone is inactive and does not encrypt secrets.

Drift

A difference between declared and observed state. Identify ownership and cause first; ignoring differences without understanding can hide an incident.

DRY

DRY

Don't Repeat Yourself

Avoid independently maintained representations of the same knowledge. Similar text in two functions does not always imply one shared rule deserving abstraction.

DTO — data transfer object

DTO

Data Transfer Object

A data structure crossing a boundary, such as an HTTP body. It separates communication format from the domain model and should not automatically expose every database-entity field.

Early Access Program

EAP

Early Access Program

Access to a product before its stable release. Check limitations and rollback options; early access is not a stability guarantee.

ECMAScript modules

ESM

ECMAScript Modules

The JavaScript module standard using import and export. Path resolution and extension handling also depend on the runtime and project configuration.

ECR

ECR

Elastic Container Registry

AWS’s container-image registry. Publishing an image does not start an application; deployments should identify an unambiguous artifact and have pull permissions.

Egress

Traffic leaving a specified boundary: a Pod, subnet or network. Name the observation point. A Pod-to-RDS request is Pod egress and database ingress.

EKS

EKS

Elastic Kubernetes Service

AWS’s managed Kubernetes service. The provider handles part of the platform, while users still own applications, permissions, costs and many operational concerns.

Elapsed duration

An amount of elapsed time between instants. Billing started 24-hour periods must include a remainder; extracting complete days alone can lose it. Do not equate duration with a calendar-day count.

Elastic IP

EIP

Elastic IP

An allocated AWS public IPv4 address attachable to supported resources. Check costs and routing; it is not an access policy.

Elastic Network Interface

ENI

Elastic Network Interface

A virtual VPC network interface with addresses and security groups. Attaching it does not replace correct routes and access rules.

Eloquent

Laravel’s ORM with record-oriented models. Convenient relation access can issue extra SQL, so inspect query counts and persistence behaviour.

Embedding

A vector representation used for tasks such as similarity search. Vector proximity does not prove truth, identical meaning or document access permission.

End of Life

EOL

End of Life

The end of a defined product support lifecycle. Determine whether it concerns fixes, a specific version or paid support; do not guess dates.

End-to-End

E2E

End-to-End

A test exercising a defined system flow. The E2E label does not prove that mocks, data and environment match production.

Endpoint

A specific API entry point, usually identified by an HTTP method and path. GET /tasks and POST /tasks may have different rules and permissions despite sharing a path.

EndpointSlice

Describes service endpoints and conditions, including readiness. Distinguishes a Service object from actual available traffic destinations.

Enum

A type representing a named set of alternatives. It helps describe state, but legal transitions still need separate rules.

Environment variable

PATH is the name of the variable containing directories searched when launching a program; it is not an acronym.

A named value passed to a process by its launch environment. It may select a mode or path but does not replace configuration validation. Child processes usually inherit the environment; changing one terminal does not automatically change other terminals or running processes.

Equality and hashCode

Objects equal according to equals must have the same hashCode. Mutating equality fields after inserting a map key can make it unfindable.

ESLint

A configurable JavaScript/TypeScript linter. A lint rule is not proof of business correctness.