🔀 AWS Step Functions

📅 Apr 15, 2026

AWS — WORKFLOW ORCHESTRATION

धेरै AWS services लाई step-by-step sequence मा coordinate गरेर run गराउने Workflow Manager

🔤 STEP 1 — Step Functions भनेको के हो? Foundation देखि

🍽️ Restaurant Analogy

Customer order दिन्छ।

Waiter → Kitchen → Cook → Plate → Deliver

Waiter = Step Functions
Cook/Kitchen = Lambda/services

→ Waiter ले cook गर्दैन — coordinate मात्र गर्छ!

💻 Tech मा के गर्छ?

▸ Lambda, Batch, ECS, SNS, DynamoDB जस्ता services लाई sequence मा run गराउँछ

▸ Step 1 सकियो → Step 2 start → Step 3...

▸ Error भयो भने automatically retry गर्छ

→ Step Functions = Conductor, Services = Musicians

🇳🇵 STEP 2 — Nepal Real Example — Esewa Payment Flow (Mind मा SET गर्नुस्!)

Esewa बाट Daraz मा order गर्दा background मा के-के steps हुन्छ — Step Functions ले यसै manage गर्छ:

🛒 Customer ले Daraz मा Order गर्यो

↓

State 1: Lambda → Order validate गर्नुस् (stock छ?)

↓ Choice: Stock छ?

✔ YES → Stock छ

State 3: Lambda → Esewa payment charge

State 4: DynamoDB → Order save

State 5: SNS → Customer लाई SMS/Email

→ SUCCESS ✔

✘ NO → Stock छैन

State 9: Lambda → Refund initiate

State 10: SNS → "Sorry, out of stock" SMS

→ FAIL (gracefully) ✘

👉 यी सबै steps Step Functions ले manage गर्छ — automatically retry, error handle, visual tracking!

🗂 STEP 3 — State Types — यो 100% Exam मा आउँछ!

Step Functions मा 8 वटा State Types छन् — हरेकको काम फरक छ।

State	के गर्छ?	Nepal Example	Exam Key
📋 Task	Lambda/Batch/ECS जस्ता service call गर्ने	Payment Lambda call गर्नुस्	Actual work गर्ने
🔀 Choice	If-Else condition check — अर्को path choose गर्ने	Payment success? YES→deliver NO→refund	Branching/condition
⏳ Wait	निश्चित समय वा event सम्म रोकिने	15 min payment window — wait गर्नुस्	Delay/timer
⚡ Parallel	धेरै branches एकैचोटि simultaneously run	SMS + Email + App notification एकैचोटि	Multiple tasks एकैचोटि
🔄 Map	Array को हरेक item मा same task repeat गर्ने	100 products को image resize एक-एकवटा	⭐ Array iteration — EXAM MA AAUXA
Pass / Succeed / Fail	Data transform / Workflow end / Error end	Order complete / Cancel confirmed	Utility states

⭐ Parallel vs Map — Exam Trap!

Parallel = फरक-फरक tasks एकैचोटि (SMS + Email + App)

Map = Same task, array items मा repeat (100 images resize)

⚡ STEP 4 — Standard vs Express Workflows — 100% EXAM MA AAUXA!

दुईटा execution mode छन् — कुन कहिले use गर्ने थाहा हुनुपर्छ।

🇳🇵 Nepal Analogy: Standard = Nepal Rastra Bank को official process (slow, complete record) | Express = eSewa instant transfer (fast, high volume)

Feature	📋 Standard	⚡ Express
Duration	Up to 1 year	Max 5 minutes
Execution Rate	2,000/second	100,000/second
Execution History	✔ Complete history	CloudWatch Logs only
Exactly-Once	✔ Yes	At-least-once
Nepal Use Case	Bank loan approval (days/weeks)	Hamro Patro को 1 लाख notification/sec
When to use	Business workflow, long process, human approval	IoT, streaming, high-throughput, short tasks

📋 Standard: Long + Complete history + Exactly-once

⚡ Express: Fast + High-volume + Short (IoT/streaming)

⚠️ STEP 5 — Common Exam Traps — यी गल्ती नगर्नुस्!

❌ Trap (गलत सोच)	✅ Correct Answer
Step Functions ले directly code execute गर्छ	Step Functions = Orchestrate मात्र। Lambda = Code execute गर्छ
Step Functions = Lambda replacement हो	Step Functions ले Lambda USE गर्छ — replace गर्दैन, साथमा काम गर्छ
Step Functions = SQS जस्तै हो	SQS = Message queue मात्र। Step Functions = Multi-step workflow manager
Heavy compute को लागि Step Functions best	Heavy compute = AWS Batch। Step Functions = Coordination manager मात्र
Array of items process = Parallel state	Array iteration = Map state। Parallel = फरक-फरक independent branches

Question	Answer
❓ MCQ Practice — Exam Style
Q1. कुन service ले workflow orchestration provide गर्छ? A) Lambda B) SQS C) Step Functions D) EventBridge	C ✔ Step Functions
Q2. Company needs to process 100 items in an array, same task each. Which state? A) Parallel B) Map C) Choice D) Task	B ✔ Map state
Q3. Complete execution history provide गर्ने execution mode? A) Express B) Standard C) Both D) Neither	B ✔ Standard
Q4. ⭐ 100,000 IoT sensor tasks per second, short duration. Which mode? A) Standard B) Express C) Lambda D) Batch	B ✔ Express (100k/sec!)
Q5. ⭐ Workflow मा human approval step चाहियो। कुन service? A) Lambda B) SQS C) Step Functions callback D) EventBridge	C ✔ Step Functions callback
Q6. Step Functions मा retry logic कसरी add गर्ने? A) Lambda भित्र code B) State definition मा Retry block C) SQS use D) Manual	B ✔ Built-in Retry block

Keyword देख्यौ	Answer	किन?
⚡ FINAL EXAM CHEATSHEET — Keyword देख्यौ = 5 second मा Answer!
Workflow / Coordinate services / Multi-step process	🔀 Step Functions	Step-by-step coordination service
Visual workflow / State machine / Retry logic / Error handling	🔀 Step Functions	Built-in features of Step Functions
Human approval / Callback / Wait for human	🔀 Step Functions (Standard)	Callback pattern support गर्छ
⭐ High-throughput / IoT / Streaming / 100k per second	⚡ Step Functions EXPRESS	Express = Fast + High volume
⭐ Array items process / Iterate over list	🔄 Map State (Parallel होइन!)	यो Trap हो — Parallel vs Map confuse नगर्नुस्!
Single function / Short event / <15 min / Serverless	⚡ Lambda (Step Functions होइन!)	1 step = Lambda, Multi-step = Step Functions