IBM Full Stack Software Developer flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Git commit object

A commit stores a pointer to a tree (the snapshot), pointers to parent commits, author and committer data, and a message. Its SHA-1 hash identifies it uniquely.

Idempotent HTTP methods

GET, PUT, DELETE, and HEAD produce the same server state when repeated. POST and PATCH are not idempotent, so retried requests may duplicate side effects unless idempotency keys are used.

REST statelessness

Each request carries all information the server needs to process it. The server keeps no client session state between calls, which simplifies scaling and lets any instance handle any request.

Agile user story

A short requirement written as role, goal, and benefit: as a user I want a capability so that I get value. Acceptance criteria define when the story is complete.

CSS specificity order

Inline styles beat IDs, IDs beat classes, attributes and pseudo-classes, which beat element and pseudo-element selectors. Later rules win only when specificity ties.

Flexbox versus Grid

Flexbox arranges items along a single main axis with wrapping. Grid defines explicit rows and columns, positioning items in two dimensions at once.

JavaScript event loop

The call stack runs synchronous code; finished microtasks (promise callbacks) drain before the next macrotask (timers, I/O callbacks). This ordering explains async output sequences.

box-sizing border-box

With border-box, a declared width includes content, padding, and border, so adding padding does not enlarge the element. The default content-box excludes padding and border from width.

React one-way data flow

Props pass data from parent to child and are read-only in the child. A child requests changes by invoking callback props, keeping state ownership predictable.

Fetch response.ok

The fetch promise rejects only on network failure. HTTP 404 or 500 responses still resolve, so code must check response.ok or the status before parsing the body.

Express middleware chain

Middleware functions receive request, response, and next. Calling next passes control onward; calling next with an error skips to error-handling middleware with four parameters.

ACID transactions

Atomicity means all statements commit or none do. Consistency enforces constraints, isolation prevents interfering concurrent reads, and durability preserves committed data across crashes.

SQL INNER versus LEFT JOIN

INNER JOIN returns only rows matching in both tables. LEFT JOIN returns every left-table row, filling right-side columns with nulls where no match exists.

JWT payload confidentiality

A JSON Web Token's payload is base64url-encoded, not encrypted. Anyone holding the token can decode its claims, so secrets and sensitive personal data must stay out.

Password hashing with salt

Store passwords as slow salted hashes such as bcrypt or Argon2. The salt defeats rainbow tables, and the slow work factor makes brute-force guessing expensive.

Database index tradeoff

Indexes accelerate lookups and sorts but add storage and slow inserts, updates, and deletes because each index must be maintained. Index columns used in filters and joins.

Node.js non-blocking I/O

Node runs JavaScript on one thread and delegates I/O to the system, resuming via callbacks. CPU-bound work blocks every request, so it belongs in worker threads or separate services.

IaaS PaaS SaaS

IaaS supplies virtual machines and networking, PaaS supplies managed runtimes and middleware, SaaS supplies complete applications. Customer control shrinks from IaaS to SaaS.

Availability zone resilience

A region contains isolated availability zones with independent power and networking. Deploying replicas across zones keeps a service running when one data center fails.

Horizontal versus vertical scaling

Horizontal scaling adds more instances behind a load balancer; vertical scaling gives one machine more CPU or memory. Stateless services scale horizontally without code changes.

Cloud shared responsibility

The provider secures physical facilities, hardware, and managed-service internals. The customer secures data, identities, access policies, and configuration of what they deploy.

Serverless cold start

A serverless function that has scaled to zero needs initialization on the next invocation, adding latency. Provisioned concurrency or keeping instances warm reduces this delay.

Container versus virtual machine

Containers share the host kernel and isolate processes, so they start fast and stay small. Virtual machines run a full guest operating system with stronger isolation and more overhead.

Docker image layers

Each Dockerfile instruction adds a read-only layer. Builders reuse cached layers while instructions and inputs are unchanged, so ordering instructions well speeds rebuilds.

Container ephemeral filesystem

Writes inside a running container live in a writable layer discarded on removal. Persistent data must go to a named volume or an external service.

Docker port publishing

The -p host:container flag maps a host port to a container port so external clients can connect. Without publishing, the container port is reachable only inside its network.

Kubernetes Pod and Deployment

A Pod is the smallest deployable unit, holding one or more containers. A Deployment manages ReplicaSets to keep the desired pod count and perform rolling updates.

Docker Compose purpose

A YAML file declares multiple services, networks, and volumes for one application. One command starts the whole stack locally, mirroring production service wiring.

Continuous integration pipeline

Every commit triggers automated build, lint, and tests. Fast feedback catches integration defects early, and a green build produces a versioned artifact for deployment.

Blue-green deployment

Two identical environments exist; the idle one receives the new release, is verified, then traffic switches over. Rollback means switching traffic back to the previous environment.

Canary release

A new version reaches a small slice of traffic first. Metrics are compared against the stable version, and the rollout expands only if health stays acceptable.

SLI SLO and SLA

An SLI is a measured indicator such as latency or error rate. An SLO is an internal target for that indicator; an SLA is a contract with customer-facing consequences.

Infrastructure as Code idempotence

Declarative templates describe desired resources. Applying the same template repeatedly converges to the same state without duplicating resources, enabling safe automated provisioning.