AI Service Architecture
Overview
This section covers the serverless AI service architecture using API Gateway, SQS, Lambda, DynamoDB, and Amazon Bedrock for intelligent assessment and content generation.
AI Service Architecture
The AI service implements a fully serverless pattern:
User → API Gateway → SQS Queue → Lambda → AI Model → DynamoDB → Response
Three Lambda Functions:
| Function | Purpose | AI Model |
|---|---|---|
| Writing Evaluate | IELTS writing assessment | Gemma 3 12B / Gemini |
| Speaking Evaluate | Audio transcription + assessment | Transcribe + Gemma 3 12B |
| Flashcard Generate | RAG-based flashcard creation | Titan Embeddings + Gemini |
Content
Request Flow
- User submits request (writing sample, audio, document)
- API Gateway validates and enqueues message to SQS
- SQS triggers appropriate Lambda function
- Lambda processes with AI model (Bedrock/Gemini)
- Results stored in DynamoDB
- User retrieves results via API
Estimated Time: ~60 minutes
Cost Estimate
Monthly Cost Summary:
| Upfront Cost | Monthly Cost | Total 12 Months Cost | Currency |
|---|---|---|---|
| $0.00 | $23.61 | $283.32 | USD |
Note: Includes upfront cost
Detailed Cost Breakdown:
| Service | Description | Region | Monthly Cost (USD) | Annual Cost (USD) |
|---|---|---|---|---|
| AWS Lambda | Writing Evaluator | Asia Pacific (Singapore) | $0.00 | $0.00 |
| AWS Lambda | Speaking Evaluator | Asia Pacific (Singapore) | $0.00 | $0.00 |
| AWS Lambda | Evaluation Status | Asia Pacific (Singapore) | $0.00 | $0.00 |
| AWS Lambda | S3 Upload | Asia Pacific (Singapore) | $0.00 | $0.00 |
| Amazon API Gateway | HTTP API | Asia Pacific (Singapore) | $0.42 | $5.04 |
| S3 Standard | Audio bucket | Asia Pacific (Singapore) | $0.51 | $6.12 |
| S3 Standard | Documents Bucket | Asia Pacific (Singapore) | $0.53 | $6.36 |
| DynamoDB | Evaluations Table | Asia Pacific (Singapore) | $0.37 | $4.44 |
| DynamoDB | Flashcard Sets Table | Asia Pacific (Singapore) | $0.52 | $6.24 |
| Amazon SQS | Writing/Speaking/Flashcard queues | Asia Pacific (Singapore) | $0.00 | $0.00 |
| AWS Secrets Manager | Secrets management | Asia Pacific (Singapore) | $0.45 | $5.40 |
| Amazon CloudWatch | RAG Lambda logs | Asia Pacific (Singapore) | $0.01 | $0.08 |
| Amazon Bedrock | Bedrock inference | US East (N. Virginia) | $0.50 | $6.00 |
| OpenAI | GPT inference | US East (N. Virginia) | $20.30 | $243.65 |
| Total | $23.61 | $283.32 |
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