Agile software development Study Guide

📖 Core Concepts Agile Software Development – A family of approaches that follow the Agile Manifesto’s values & principles. Values (the 4 pillars) – Individuals & interactions, Working software, Customer collaboration, Responding to change. Principles – 12 guiding ideas (e.g., early delivery, welcome change, daily cooperation, sustainable pace, technical excellence, self‑organizing teams). Iterative & Incremental Development – Work is split into iterations (1‑4 weeks) that each produce a usable product increment. Cross‑functional, Self‑organizing Teams – Team members with all needed skills collaborate directly with customers. Backlog – Prioritized list of user stories/features; continuously refined (product backlog, iteration backlog). Velocity – Measure of how many story points (or similar units) a team completes per iteration; gauges delivery speed. Technical Debt – “Interest” on shortcut code; adds unscheduled work, defects, and slows future velocity. Work‑In‑Progress (WIP) Limits – Restrict the number of items a team works on simultaneously to reduce context‑switching. Information Radiator – Large, visible display of current status (e.g., sprint board, burn‑down chart). --- 📌 Must Remember Four Agile values – Individuals & interactions > processes & tools; Working software > comprehensive documentation; Customer collaboration > contract negotiation; Responding to change > following a plan. Iteration length – Typically 1–4 weeks; time, quality, and team size are fixed; scope is flexible. Daily Stand‑Up – 15‑minute sync: What I did yesterday, What I’ll do today, Impediments. Velocity – Calculated each iteration; used for forecasting, not for measuring quality. Technical Debt Effect – Increases unscheduled work, defect rate, and future cost; must be counter‑acted by regular refactoring. Continuous Integration – Merge code frequently; automated tests run on each integration. Backlog Commitment – The iteration backlog is a team agreement on what can be finished within the fixed parameters. Self‑Organizing Teams – Best architecture & design emerge when the team selects its own work. Key Agile Frameworks – Scrum, Extreme Programming (XP), Kanban, Lean, SAFe, Large‑Scale Scrum. --- 🔄 Key Processes Iteration Planning Fix time, quality, resources. Choose what can be delivered (scope) based on current capacity (velocity). Daily Stand‑Up Each member answers the three questions; problem‑solving happens after the meeting. Backlog Refinement (Grooming) Ongoing: split, estimate, prioritize stories; keep the backlog “ready”. Continuous Integration (CI) Developers commit often → automated build + test suite → immediate feedback. Retrospective (end of iteration) Team reflects on what worked, what didn’t, and decides on process improvements. Definition of Done (DoD) Shared checklist (code complete, tests passing, documentation “just enough”, deployed to staging). --- 🔍 Key Comparisons Agile vs. Waterfall (Testing) Agile: testing in the same iteration as coding. Waterfall: testing after the entire build phase. Agile vs. Waterfall (Planning) Agile: iterative planning & frequent re‑prioritization. Waterfall: detailed, upfront plan locked at project start. Adaptive vs. Predictive Development Adaptive: rolling‑wave schedule, broad future descriptions. Predictive: detailed tasks & milestones set far in advance. Push‑Based vs. Pull‑Based Coaching Push: tasks are pushed into a sprint (Scrum). Pull: tasks are pulled when capacity is available (Kanban). Scrum vs. Kanban Scrum: fixed‑time sprints, defined roles, sprint backlog. Kanban: continuous flow, WIP limits, no prescribed time boxes. --- ⚠️ Common Misunderstandings “Agile means no documentation.” → Agile prefers just‑enough documentation that answers “What would a new teammate need to know tomorrow?” “Agile has no planning.” → Agile plans iteratively; each iteration is carefully planned. “Velocity is a quality metric.” → Velocity measures how much is delivered, not how good it is. “Technical debt is intentional.” → Debt often accumulates unintentionally; it must be managed, not ignored. “Large organizations can’t be Agile.” → Scaled frameworks (SAFe, LeSS) exist, though they add coordination overhead. --- 🧠 Mental Models / Intuition Time‑Boxed, Scope‑Flexible – Imagine a hard bucket (time) you can pour any water (features) into; overflow (excess scope) spills and damages quality. Technical Debt as Interest – The more shortcuts you take, the higher the “interest” (extra effort) you pay later. Information Radiator = Dashboard – Like a car’s speedometer, it instantly shows health of the sprint. Velocity = Speedometer, not Fuel Gauge – It tells you how fast you’re moving, not how efficiently you’re using resources. --- 🚩 Exceptions & Edge Cases Distributed Agile – Requires robust tooling (virtual boards, video stand‑ups) to keep the information radiator visible. Large‑Scale Agile (>20 devs) – May need additional roles (Release Train Engineer) and coordination ceremonies (PI Planning). When Documentation Is Critical – Regulated industries (e.g., medical, aerospace) demand more formal artifacts despite Agile values. Adding Work Mid‑Iteration – Should be deferred to the next iteration’s backlog unless a critical emergency arises. --- 📍 When to Use Which Scrum – Fixed‑length sprints, clear roles, need for predictable cadence. Kanban – Continuous delivery, variable work size, strong focus on limiting WIP. Extreme Programming (XP) – Heavy emphasis on engineering practices (pair programming, TDD). SAFe / Large‑Scale Scrum – Organizations with many teams needing alignment and program‑level planning. Pull‑Based Coaching – When team overload is common; helps enforce WIP limits. Push‑Based Coaching – When a stable sprint cadence is already working and capacity is well understood. --- 👀 Patterns to Recognize “Iterate → Demo → Feedback → Adapt” – Loop appears in almost every Agile exam question. “Self‑Organizing → Emergent Architecture” – Indicates the team, not a manager, decides design. “Continuous Integration + Automated Tests” – Signals a quality‑focused Agile practice. “Fixed Time, Variable Scope” – A hallmark of Agile iteration planning. “Technical Debt → Refactor → Reduce Defects” – Shows the cause‑effect chain. --- 🗂️ Exam Traps Distractor: “Agile eliminates all documentation.” – Wrong; Agile uses just‑enough documentation. Distractor: “Higher velocity always means a healthier team.” – Velocity is a capacity metric; quality can still suffer. Distractor: “Technical debt is a purposeful, beneficial strategy.” – Debt is a risk that must be managed, not a goal. Distractor: “You can add new user stories to an ongoing iteration without impact.” – Adding scope breaks the fixed‑time, fixed‑resource principle and can degrade quality. Distractor: “Large organizations cannot adopt Agile.” – Scaled frameworks exist; the issue is often cultural, not methodological. ---