mcp-quickbase/docs/architecture.md

Work with Quickbase via Model Context Protocol

# 🏗️ Quickbase MCP Server Architecture

## 📋 Architecture Overview

The Quickbase MCP Server follows a layered architecture:

```
┌────────────────────────────────────┐
│           MCP Interface            │
└────────────────────┬───────────────┘
                     │
┌────────────────────▼───────────────┐
│         Quickbase Client           │
│                                    │
│  ┌──────────┐  ┌────────────────┐  │
│  │  Cache   │  │  Error Handler │  │
│  └──────────┘  └────────────────┘  │
│                                    │
│  ┌──────────┐  ┌────────────────┐  │
│  │  Logger  │  │  Retry Logic   │  │
│  └──────────┘  └────────────────┘  │
└────────────────────┬───────────────┘
                     │
┌────────────────────▼───────────────┐
│        Quickbase REST API          │
└────────────────────────────────────┘
```

## 📊 Components

### 🔗 MCP Interface
- Exposes MCP-compliant tools
- Handles parameter validation with JSON Schema
- Formats responses according to MCP standards
- Supports both stdio and HTTP transports

### 🔄 Quickbase Client
- Core client for interacting with Quickbase REST API
- Manages authentication and HTTP requests
- Implements TypeScript-first API wrappers
- Provides structured error handling

### 🛠️ Supporting Services

#### 📋 Cache Service
- Stores frequently accessed data (table schemas, field definitions)
- Implements intelligent cache invalidation
- Configurable TTL settings (default: 1 hour)
- LRU eviction policy for memory management

#### ⚠️ Error Handler
- Classifies and formats API errors
- Provides detailed error context for debugging
- Handles error recovery with exponential backoff
- Redacts sensitive information from error logs

#### 📝 Logger
- Structured logging with configurable levels
- Automatic PII and sensitive data redaction
- JSON-formatted logs for machine processing
- Context-aware logging with request tracing

#### 🔄 Retry Logic
- Handles transient HTTP and network errors
- Implements exponential backoff with jitter
- Configurable retry limits and timeouts
- Circuit breaker pattern for failing services

## 🏢 Separation of Concerns

The architecture follows clean separation principles:

### 1. 🔗 Interface Layer (MCP Tools)
- **Responsibility**: Expose Quickbase functionality via MCP protocol
- **Components**: Tool registry, parameter validation, response formatting
- **Benefits**: Protocol-agnostic business logic, easy testing

### 2. 💼 Business Logic Layer (Quickbase Client)
- **Responsibility**: Core Quickbase operations and data transformations
- **Components**: API client, data models, business rules
- **Benefits**: Reusable across different interfaces, focused testing

### 3. 🛠️ Infrastructure Layer
- **Responsibility**: Cross-cutting concerns and external dependencies
- **Components**: Cache, logging, error handling, retry logic
- **Benefits**: Centralized infrastructure management, easy configuration

### 📊 Benefits of This Architecture

- **🧪 Testability**: Each layer can be tested in isolation
- **🔄 Maintainability**: Changes are isolated to specific layers
- **🚀 Scalability**: Infrastructure components can be optimized independently
- **🔌 Flexibility**: Interface layer can be swapped without affecting business logic
- **🔒 Security**: Centralized handling of authentication and data protection