Glossary
Common terms and definitions used in the NorthBuilt RAG System documentation.
Table of contents
A
API Gateway
AWS service that creates and manages HTTP APIs. We use HTTP API (not REST API) for lower cost and better performance.
ARN (Amazon Resource Name)
Unique identifier for AWS resources. Format: arn:aws:service:region:account-id:resource-type/resource-id
AWS Bedrock
AWS managed service for AI foundation models (documentation). We use it for:
- Claude Sonnet 4.5: Response generation
- Titan Embeddings V2: Vector embeddings
B
Bootstrap
The process of setting up foundational AWS resources before Terraform can deploy:
- S3 bucket for Terraform state
- DynamoDB table for state locking
- GitHub OIDC provider
- IAM role for GitHub Actions
C
Claude Sonnet 4.5
Anthropic’s AI model for natural language generation. We use it via AWS Bedrock for generating responses from retrieved context.
Model ID: us.anthropic.claude-sonnet-4-5-20250929-v1:0
Cost: $3/M input tokens, $15/M output tokens
CloudFront
AWS Content Delivery Network (CDN) that distributes the web UI globally for low latency.
CloudWatch
AWS monitoring service providing logs, metrics, and alarms for the system.
Cognito
AWS authentication service. We use it for user management and Google OAuth integration.
CORS (Cross-Origin Resource Sharing)
Browser security mechanism allowing the web UI to call the API Gateway from a different domain.
Cosine Similarity
Mathematical measure of similarity between two vectors, used by S3 Vectors to find relevant documents. Range: -1 to 1 (1 = identical, 0 = unrelated, -1 = opposite).
D
DynamoDB
AWS NoSQL database. We use it for:
- Terraform state locking
- Document classification results
E
Embedding
Numerical vector representation of text that captures semantic meaning. Generated by Titan Embeddings V2 (1024 dimensions).
Example: "serverless architecture" → [0.23, -0.45, 0.67, ...] (1024 numbers)
F
Foundation Model
Pre-trained AI model available on AWS Bedrock. We use:
- Claude Sonnet 4.5 for text generation
- Titan Embeddings V2 for embeddings
G
GitHub Actions
CI/CD platform integrated with GitHub. We use it for automated Terraform deployments via OIDC.
GitHub Pages
Static site hosting provided by GitHub. Hosts our documentation at https://craftcodery.github.io/compass
H
HTTP API
Type of API Gateway that’s simpler and cheaper than REST API. Lacks some features (caching, usage plans) but 70% cheaper.
I
IAM (Identity and Access Management)
AWS service for managing permissions. We use it for Lambda execution roles with least-privilege policies.
IaC (Infrastructure as Code)
Managing infrastructure through code (Terraform) rather than manual configuration.
J
Jekyll
Static site generator used by GitHub Pages to build documentation websites from Markdown files.
JWT (JSON Web Token)
Token format used by Cognito for authentication. Contains user identity and is cryptographically signed.
K
Knowledge Base
Collection of documents that can be searched semantically (documentation). In our system, documents are stored as vectors in S3 Vectors via Bedrock Knowledge Base.
L
Lambda
AWS serverless compute service. We have multiple Lambda functions:
- Chat: Main orchestrator (query understanding, Bedrock KB retrieval, response generation)
- Classify: Document classification via domain mapping
- Ingest: Document ingestion to S3/Bedrock KB
- Webhooks: Fathom, HelpScout, Linear (3 handlers)
- Sync: Fathom, HelpScout, Linear (3 sync functions with workers)
Lambda Cold Start
Delay (~1 second) when Lambda function is invoked for the first time or after being idle. Can be eliminated with provisioned concurrency.
M
MAU (Monthly Active Users)
Cognito pricing metric. First 50K MAU are free.
N
Namespace
Logical partition within a vector index. Used for multi-tenancy isolation.
O
OAuth 2.0
Industry-standard protocol for authorization. We use Google OAuth for user authentication via Cognito.
OIDC (OpenID Connect)
Authentication layer on top of OAuth 2.0. GitHub Actions uses OIDC to authenticate with AWS without long-lived credentials.
OpenSearch Serverless
AWS vector database we used initially. Replaced with S3 Vectors for cost savings and simpler architecture.
P
Pinecone
Third-party managed vector database. Previously used in our system (see ADR-010). Replaced with S3 Vectors for native AWS integration.
PITR (Point-in-Time Recovery)
DynamoDB feature allowing restore to any point in last 35 days. Enabled on classify table.
Q
Query
User question submitted to the chat API. Example: “What is the system architecture?”
Query Lambda
Deprecated. Document retrieval is now handled directly by the Chat Lambda via Bedrock Knowledge Base APIs.
R
RAG (Retrieval-Augmented Generation)
AI technique combining retrieval (find relevant documents) with generation (create response using documents as context).
Flow: User query → Generate embedding → Search vectors → Retrieve documents → Generate response
Reserved Concurrency
Number of Lambda instances reserved for a function, preventing runaway costs from infinite loops.
Route53
AWS DNS service. Can be used for custom domain setup (optional).
S
S3 (Simple Storage Service)
AWS object storage. We use it for:
- Terraform state file
- Web UI static assets
Secrets Manager
AWS service for storing sensitive data (API keys, passwords). We store:
- Fathom, HelpScout, Linear API keys
- Google OAuth client secret
Semantic Search
Search based on meaning rather than keyword matching. Uses vector embeddings and similarity measures.
Example: Query “serverless compute” matches documents about “Lambda” even though “serverless” isn’t in the text.
Serverless
Architecture pattern where cloud provider manages servers. Benefits: auto-scaling, pay-per-use, no server management.
T
Terraform
Infrastructure as Code tool for provisioning AWS resources. We use it to deploy 100% of our infrastructure.
Throttling
Rate limiting mechanism in API Gateway to prevent abuse. Current limits: 10 req/s, 20 burst.
Titan Embeddings V2
AWS Bedrock model for generating text embeddings (1024 dimensions) (documentation).
Model ID: amazon.titan-embed-text-v2:0
Cost: $0.0001 per 1000 tokens
U
Upsert
Vector database operation to insert or update vectors. “Upsert” = insert + update.
V
Vector
Array of numbers representing text semantically. Example: 1024-dimensional vector from Titan.
Vector Database
Database optimized for storing and querying high-dimensional vectors. We use S3 Vectors via Bedrock Knowledge Base.
VPC (Virtual Private Cloud)
AWS isolated network. Not used in our architecture for simplicity.
S (Additional)
S3 Vectors
AWS purpose-built vector storage for Bedrock Knowledge Base (documentation). Native integration with zero infrastructure management.
Configuration:
- Dimension: 1024 (matches Titan embeddings)
- Metric: Cosine similarity
- Storage: Fully managed by AWS
- Non-filterable keys:
AMAZON_BEDROCK_TEXT,AMAZON_BEDROCK_METADATA(required for 100% ingestion) - Data deletion policy: DELETE (vectors auto-removed when S3 docs deleted)
Important: LLM parsing is disabled. Metadata is provided via sidecar .metadata.json files to avoid the 2KB filterable metadata limit (metadata filtering).
W
Webhook
HTTP callback mechanism where external service sends data to our API when events occur.
We support webhooks from:
- Fathom: Video transcripts
- HelpScout: Support tickets
- Linear: Teams (clients) for entity registry; projects synced for display purposes
X
X-Ray
AWS distributed tracing service. Can be enabled on Lambda functions for performance debugging (optional).
Acronyms
| Acronym | Full Form | Description |
|---|---|---|
| ACM | AWS Certificate Manager | SSL/TLS certificates |
| ADR | Architecture Decision Record | Documentation of design decisions |
| API | Application Programming Interface | HTTP endpoints |
| ARN | Amazon Resource Name | AWS resource identifier |
| CDN | Content Delivery Network | CloudFront |
| CORS | Cross-Origin Resource Sharing | Browser security |
| HTTP | Hypertext Transfer Protocol | Web protocol |
| IAM | Identity and Access Management | AWS permissions |
| IaC | Infrastructure as Code | Terraform |
| JWT | JSON Web Token | Authentication token |
| LLM | Large Language Model | Claude Sonnet 4.5 |
| MAU | Monthly Active Users | Cognito pricing |
| OIDC | OpenID Connect | Authentication protocol |
| PITR | Point-in-Time Recovery | DynamoDB backups |
| RAG | Retrieval-Augmented Generation | AI architecture pattern |
| S3 | Simple Storage Service | Object storage |
| SLA | Service Level Agreement | Uptime guarantee |
| SNS | Simple Notification Service | AWS alerts |
| SSE | Server-Side Encryption | Encryption at rest |
| TLS | Transport Layer Security | Encryption in transit |
| VPC | Virtual Private Cloud | AWS network isolation |
Last updated: 2026-01-01