# SciRS2 Core 1.0 Architecture and Scaling Guide

## Table of Contents

1. [Architecture Overview](#architecture-overview)
2. [Component Architecture](#component-architecture)
3. [Deployment Architectures](#deployment-architectures)
4. [Scaling Patterns](#scaling-patterns)
5. [Performance Architecture](#performance-architecture)
6. [Distributed Computing](#distributed-computing)
7. [Cloud-Native Deployment](#cloud-native-deployment)
8. [Edge Computing](#edge-computing)
9. [Integration Patterns](#integration-patterns)
10. [Migration Strategies](#migration-strategies)

## Architecture Overview

SciRS2 Core 1.0 is designed as a modular, high-performance scientific computing library with enterprise-grade scalability, observability, and reliability features. The architecture supports multiple deployment patterns from single-node setups to large-scale distributed clusters.

### Core Design Principles

1. **Modularity**: Loosely coupled modules with well-defined interfaces
2. **Performance**: SIMD, parallel, and GPU acceleration at all levels
3. **Scalability**: Horizontal and vertical scaling capabilities
4. **Observability**: Built-in metrics, tracing, and monitoring
5. **Reliability**: Fault tolerance and graceful degradation
6. **Security**: Defense in depth with comprehensive audit trails

### High-Level Architecture

```
┌─────────────────────────────────────────────────────────────────┐
│                     SciRS2 Core 1.0 Architecture               │
├─────────────────────────────────────────────────────────────────┤
│  Application Layer                                              │
│  ┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐   │
│  │   Web Services  │ │  Batch Jobs     │ │  Interactive    │   │
│  │                 │ │                 │ │  Notebooks      │   │
│  └─────────────────┘ └─────────────────┘ └─────────────────┘   │
├─────────────────────────────────────────────────────────────────┤
│  SciRS2 Core API Layer                                         │
│  ┌─────────────────────────────────────────────────────────┐   │
│  │  Core APIs │ LinAlg │ Stats │ Signal │ Spatial │ ... │   │
│  └─────────────────────────────────────────────────────────┘   │
├─────────────────────────────────────────────────────────────────┤
│  Execution Engine Layer                                        │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐           │
│  │ CPU/SIMD     │ │ Multi-Core   │ │ GPU/CUDA     │           │
│  │ Engine       │ │ Parallel     │ │ Engine       │           │
│  └──────────────┘ └──────────────┘ └──────────────┘           │
├─────────────────────────────────────────────────────────────────┤
│  Storage and Memory Layer                                      │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐           │
│  │ Memory-      │ │ Distributed  │ │ Cloud        │           │
│  │ Mapped       │ │ Storage      │ │ Storage      │           │
│  └──────────────┘ └──────────────┘ └──────────────┘           │
├─────────────────────────────────────────────────────────────────┤
│  Cross-Cutting Concerns                                        │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐           │
│  │ Observability│ │ Security     │ │ Configuration│           │
│  │ & Monitoring │ │ & Audit      │ │ Management   │           │
│  └──────────────┘ └──────────────┘ └──────────────┘           │
└─────────────────────────────────────────────────────────────────┘
```

## Component Architecture

### Core Module Structure

```rust
// Core module architecture
pub mod scirs2_core {
    pub mod execution {
        pub mod simd;          // SIMD acceleration
        pub mod parallel;      // Multi-core processing
        pub mod gpu;           // GPU acceleration
        pub mod distributed;   // Distributed computing
    }
    
    pub mod memory {
        pub mod efficient;     // Memory-efficient operations
        pub mod mapped;        // Memory-mapped arrays
        pub mod pools;         // Memory pool management
        pub mod compression;   // Data compression
    }
    
    pub mod observability {
        pub mod metrics;       // Performance metrics
        pub mod tracing;       // Distributed tracing
        pub mod audit;         // Audit logging
        pub mod health;        // Health monitoring
    }
    
    pub mod scaling {
        pub mod horizontal;    // Horizontal scaling
        pub mod vertical;      // Vertical scaling
        pub mod elastic;       // Auto-scaling
        pub mod load_balancing; // Load distribution
    }
}
```

### Module Dependencies

```
scirs2-core (Foundation)
├── scirs2-linalg (Linear Algebra)
│   ├── scirs2-core
│   └── BLAS/LAPACK bindings
├── scirs2-stats (Statistics)
│   ├── scirs2-core
│   └── scirs2-linalg
├── scirs2-signal (Signal Processing)
│   ├── scirs2-core
│   ├── scirs2-linalg
│   └── scirs2-fft
├── scirs2-spatial (Spatial Operations)
│   ├── scirs2-core
│   └── scirs2-stats
└── scirs2 (Main Integration)
    └── All modules via feature flags
```

### Data Flow Architecture

```
Input Data
    ↓
┌─────────────────┐
│ Data Validation │
│ & Preprocessing │
└─────────────────┘
    ↓
┌─────────────────┐
│ Memory Management│
│ & Optimization  │
└─────────────────┘
    ↓
┌─────────────────┐
│ Execution Engine│
│ Selection       │
└─────────────────┘
    ↓
┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│ CPU/SIMD        │  OR │ Parallel        │  OR │ GPU/Distributed │
│ Processing      │     │ Processing      │     │ Processing      │
└─────────────────┘     └─────────────────┘     └─────────────────┘
    ↓                       ↓                       ↓
┌─────────────────────────────────────────────────────────────────┐
│                    Result Aggregation                          │
└─────────────────────────────────────────────────────────────────┘
    ↓
┌─────────────────┐
│ Output          │
│ Serialization   │
└─────────────────┘
    ↓
Output Data
```

## Deployment Architectures

### Single-Node Deployment

```yaml
# docker-compose.yml for single-node deployment
version: '3.8'
services:
  scirs2-core:
    image: scirs2/core:1.0
    ports:
      - "8080:8080"
    environment:
      - SCIRS2_NUM_THREADS=8
      - SCIRS2_MEMORY_LIMIT=8192
      - SCIRS2_ENABLE_GPU=true
    volumes:
      - ./data:/var/lib/scirs2/data
      - ./config:/etc/scirs2
    resource_limits:
      cpus: '8'
      memory: 16G
    
  prometheus:
    image: prom/prometheus
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
      
  grafana:
    image: grafana/grafana
    ports:
      - "3000:3000"
    environment:
      - GF_SECURITY_ADMIN_PASSWORD=admin123
```

#### Single-Node Performance Characteristics
- **CPU**: 8-64 cores optimal
- **Memory**: 16GB-512GB depending on workload
- **Storage**: NVMe SSD recommended for data and temp files
- **Network**: 1-10 Gbps for data transfer
- **Throughput**: 10K-100K operations/second

### Multi-Node Cluster Deployment

```yaml
# kubernetes-cluster.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: scirs2-core-cluster
spec:
  replicas: 5
  selector:
    matchLabels:
      app: scirs2-core
  template:
    metadata:
      labels:
        app: scirs2-core
    spec:
      containers:
      - name: scirs2-core
        image: scirs2/core:1.0
        ports:
        - containerPort: 8080
        env:
        - name: SCIRS2_CLUSTER_MODE
          value: "true"
        - name: SCIRS2_CLUSTER_SIZE
          value: "5"
        - name: SCIRS2_DISCOVERY_SERVICE
          value: "etcd.scirs2.svc.cluster.local:2379"
        resources:
          requests:
            cpu: "4"
            memory: "8Gi"
          limits:
            cpu: "8"
            memory: "16Gi"
---
apiVersion: v1
kind: Service
metadata:
  name: scirs2-core-service
spec:
  selector:
    app: scirs2-core
  ports:
  - port: 8080
    targetPort: 8080
  type: LoadBalancer
```

#### Cluster Performance Characteristics
- **Nodes**: 3-100+ nodes
- **Per-Node Resources**: 4-32 cores, 16-128GB RAM
- **Network**: 10-100 Gbps inter-node communication
- **Throughput**: 100K-10M operations/second
- **Latency**: 10-100ms for distributed operations

### High-Availability Deployment

```yaml
# ha-deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: scirs2-core-ha
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  selector:
    matchLabels:
      app: scirs2-core
      tier: production
  template:
    metadata:
      labels:
        app: scirs2-core
        tier: production
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - scirs2-core
            topologyKey: kubernetes.io/hostname
      containers:
      - name: scirs2-core
        image: scirs2/core:1.0
        ports:
        - containerPort: 8080
        - containerPort: 9090  # metrics
        livenessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 30
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /ready
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 5
        env:
        - name: SCIRS2_HA_MODE
          value: "true"
        - name: SCIRS2_REPLICATION_FACTOR
          value: "3"
```

## Scaling Patterns

### Horizontal Scaling

#### Auto-Scaling Configuration
```rust
use scirs2_core::scaling::{HorizontalScaler, ScalingPolicy};

// Configure horizontal scaling
let scaling_policy = ScalingPolicy::new()
    .with_min_replicas(3)
    .with_max_replicas(50)
    .with_target_cpu_utilization(70.0)
    .with_target_memory_utilization(80.0)
    .with_scale_up_threshold(2)     // Scale up after 2 measurement periods
    .with_scale_down_threshold(5)   // Scale down after 5 measurement periods
    .with_scale_up_increment(2)     // Add 2 replicas at a time
    .with_scale_down_increment(1);  // Remove 1 replica at a time

let horizontal_scaler = HorizontalScaler::new(scaling_policy);

// Monitor and scale
horizontal_scaler.start_monitoring()?;
```

#### Load-Based Scaling
```rust
use scirs2_core::scaling::{LoadBalancer, LoadMetrics};

// Configure load-based scaling
let load_balancer = LoadBalancer::new()
    .with_algorithm(LoadBalancingAlgorithm::WeightedRoundRobin)
    .with_health_checks(true)
    .with_circuit_breaker(true);

// Custom scaling logic based on queue depth
let load_metrics = LoadMetrics::collect();
if load_metrics.queue_depth > 1000 {
    horizontal_scaler.scale_up(2)?;
} else if load_metrics.queue_depth < 100 && load_metrics.avg_cpu < 30.0 {
    horizontal_scaler.scale_down(1)?;
}
```

### Vertical Scaling

#### Dynamic Resource Allocation
```rust
use scirs2_core::scaling::{VerticalScaler, ResourceProfile};

// Configure vertical scaling
let resource_profiles = vec![
    ResourceProfile::new("small")
        .with_cpu_cores(4)
        .with_memory_gb(8)
        .with_cost_per_hour(0.20),
    ResourceProfile::new("medium")
        .with_cpu_cores(8)
        .with_memory_gb(16)
        .with_cost_per_hour(0.40),
    ResourceProfile::new("large")
        .with_cpu_cores(16)
        .with_memory_gb(32)
        .with_cost_per_hour(0.80),
    ResourceProfile::new("xlarge")
        .with_cpu_cores(32)
        .with_memory_gb(64)
        .with_cost_per_hour(1.60),
];

let vertical_scaler = VerticalScaler::new(resource_profiles);

// Automatic profile selection based on workload
let current_workload = WorkloadAnalyzer::analyze_current_workload()?;
let optimal_profile = vertical_scaler.recommend_profile(&current_workload)?;
vertical_scaler.apply_profile(&optimal_profile)?;
```

### Elastic Scaling

#### Predictive Scaling
```rust
use scirs2_core::scaling::{PredictiveScaler, WorkloadPredictor};

// Configure predictive scaling
let workload_predictor = WorkloadPredictor::new()
    .with_historical_data_days(30)
    .with_prediction_horizon_hours(24)
    .with_confidence_threshold(0.85);

let predictive_scaler = PredictiveScaler::new(workload_predictor);

// Scale based on predictions
let predicted_load = predictive_scaler.predict_load(
    chrono::Utc::now() + chrono::Duration::hours(1)
)?;

if predicted_load.expected_operations_per_second > 50000 {
    predictive_scaler.pre_scale_for_load(&predicted_load)?;
}
```

#### Event-Driven Scaling
```rust
use scirs2_core::scaling::{EventDrivenScaler, ScalingEvent};

// Configure event-driven scaling
let event_scaler = EventDrivenScaler::new()
    .with_event_source("kafka://events.scirs2.internal:9092")
    .with_scaling_rules(vec![
        ScalingRule::new("batch_job_submitted")
            .scale_up(5)
            .with_timeout(Duration::from_secs(3600)),
        ScalingRule::new("emergency_computation")
            .scale_up(10)
            .with_priority(ScalingPriority::High),
    ]);

// React to scaling events
event_scaler.on_event(|event: ScalingEvent| {
    match event.event_type.as_str() {
        "large_dataset_upload" => {
            // Pre-emptively scale for data processing
            Ok(ScalingAction::ScaleUp(3))
        },
        "peak_hour_start" => {
            // Scale for expected load increase
            Ok(ScalingAction::ScaleUp(5))
        },
        _ => Ok(ScalingAction::NoAction)
    }
})?;
```

## Performance Architecture

### CPU Optimization Architecture

```rust
use scirs2_core::performance::{CpuOptimizer, CpuTopology};

// Detect and optimize for CPU topology
let cpu_topology = CpuTopology::detect()?;
let cpu_optimizer = CpuOptimizer::new(&cpu_topology);

// Configure NUMA-aware processing
cpu_optimizer.configure_numa_affinity()?;
cpu_optimizer.optimize_thread_placement()?;

// Enable specific CPU features
if cpu_topology.supports_avx512() {
    cpu_optimizer.enable_avx512()?;
}
if cpu_topology.supports_tensor_operations() {
    cpu_optimizer.enable_tensor_acceleration()?;
}
```

### Memory Architecture

```rust
use scirs2_core::memory::{MemoryArchitect, MemoryTopology};

// Design optimal memory layout
let memory_topology = MemoryTopology::detect()?;
let memory_architect = MemoryArchitect::new(&memory_topology);

// Configure memory pools
let memory_pools = memory_architect.design_memory_pools(
    &[
        PoolSpec::new("compute_pool")
            .with_size_gb(32)
            .with_numa_node(0)
            .with_huge_pages(true),
        PoolSpec::new("io_pool")
            .with_size_gb(8)
            .with_numa_node(1)
            .with_prefault(true),
    ]
)?;

// Apply memory optimizations
memory_architect.apply_optimizations(&memory_pools)?;
```

### GPU Architecture

```rust
use scirs2_core::gpu::{GpuArchitect, GpuTopology, MultiGpuStrategy};

// Design multi-GPU processing architecture
let gpu_topology = GpuTopology::detect()?;
let gpu_architect = GpuArchitect::new(&gpu_topology);

// Configure multi-GPU strategy
let multi_gpu_strategy = match gpu_topology.gpu_count() {
    1 => MultiGpuStrategy::Single,
    2..=4 => MultiGpuStrategy::DataParallel,
    5..=8 => MultiGpuStrategy::ModelParallel,
    _ => MultiGpuStrategy::Hybrid,
};

gpu_architect.configure_multi_gpu_strategy(multi_gpu_strategy)?;

// Optimize GPU memory management
gpu_architect.optimize_memory_management()?;
gpu_architect.enable_peer_to_peer_transfer()?;
```

### Storage Architecture

```rust
use scirs2_core::storage::{StorageArchitect, StorageTier};

// Design tiered storage architecture
let storage_architect = StorageArchitect::new();

let storage_tiers = vec![
    StorageTier::new("hot")
        .with_type(StorageType::NVMe)
        .with_capacity_gb(1024)
        .with_iops(100000)
        .with_latency_us(100),
    StorageTier::new("warm")
        .with_type(StorageType::SSD)
        .with_capacity_gb(10240)
        .with_iops(50000)
        .with_latency_us(500),
    StorageTier::new("cold")
        .with_type(StorageType::HDD)
        .with_capacity_gb(102400)
        .with_iops(1000)
        .with_latency_ms(10),
];

storage_architect.configure_tiered_storage(storage_tiers)?;

// Auto-tier data based on access patterns
storage_architect.enable_auto_tiering()?;
```

## Distributed Computing

### Cluster Architecture

```rust
use scirs2_core::distributed::{ClusterManager, NodeRole, ClusterTopology};

// Initialize cluster management
let cluster_manager = ClusterManager::new()
    .with_discovery_service("etcd://cluster.scirs2.internal:2379")
    .with_cluster_name("scirs2-production")
    .with_encryption(true);

// Define cluster topology
let cluster_topology = ClusterTopology::new()
    .with_coordinator_nodes(3)
    .with_compute_nodes(20)
    .with_storage_nodes(5)
    .with_replication_factor(3);

// Join cluster
cluster_manager.join_cluster(NodeRole::Compute, cluster_topology)?;
```

### Distributed Processing

```rust
use scirs2_core::distributed::{DistributedArray, DistributedCompute};

// Create distributed arrays
let distributed_data = DistributedArray::from_local_array(
    local_array,
    DistributionStrategy::BlockDistribution { block_size: 1_000_000 }
)?;

// Distributed computation
let result = DistributedCompute::new()
    .with_fault_tolerance(true)
    .with_checkpointing(true)
    .map(&distributed_data, |chunk| {
        // Process each chunk
        chunk.mapv(|x| x * 2.0 + 1.0)
    })?
    .reduce(|acc, chunk| {
        // Reduce results
        acc + chunk.sum()
    })?;
```

### Fault Tolerance

```rust
use scirs2_core::distributed::{FaultTolerance, CheckpointManager};

// Configure fault tolerance
let fault_tolerance = FaultTolerance::new()
    .with_replication_factor(3)
    .with_node_failure_detection(Duration::from_secs(30))
    .with_automatic_recovery(true);

// Checkpoint management
let checkpoint_manager = CheckpointManager::new()
    .with_checkpoint_interval(Duration::from_secs(300))  // 5 minutes
    .with_storage_backend("s3://scirs2-checkpoints/")
    .with_compression(true);

// Execute fault-tolerant computation
fault_tolerance.execute_with_checkpoints(
    &checkpoint_manager,
    || {
        // Your computation here
        long_running_computation()
    }
)?;
```

## Cloud-Native Deployment

### Kubernetes Deployment

```yaml
# Complete Kubernetes deployment
apiVersion: v1
kind: Namespace
metadata:
  name: scirs2
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: scirs2-config
  namespace: scirs2
data:
  config.toml: |
    [runtime]
    num_threads = 8
    memory_limit_mb = 8192
    
    [observability]
    metrics_endpoint = "http://prometheus.monitoring.svc.cluster.local:9090"
    tracing_endpoint = "http://jaeger.monitoring.svc.cluster.local:14268"
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: scirs2-core
  namespace: scirs2
spec:
  replicas: 5
  selector:
    matchLabels:
      app: scirs2-core
  template:
    metadata:
      labels:
        app: scirs2-core
    spec:
      containers:
      - name: scirs2-core
        image: scirs2/core:1.0
        ports:
        - containerPort: 8080
        - containerPort: 9090
        volumeMounts:
        - name: config
          mountPath: /etc/scirs2
        - name: data
          mountPath: /var/lib/scirs2
        resources:
          requests:
            cpu: "4"
            memory: "8Gi"
            nvidia.com/gpu: "1"
          limits:
            cpu: "8"
            memory: "16Gi"
            nvidia.com/gpu: "1"
      volumes:
      - name: config
        configMap:
          name: scirs2-config
      - name: data
        persistentVolumeClaim:
          claimName: scirs2-data
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: scirs2-data
  namespace: scirs2
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Ti
  storageClassName: fast-ssd
```

### Service Mesh Integration

```yaml
# Istio service mesh configuration
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: scirs2-core
  namespace: scirs2
spec:
  hosts:
  - scirs2-core
  http:
  - match:
    - headers:
        priority:
          exact: high
    route:
    - destination:
        host: scirs2-core
        subset: high-priority
      weight: 100
  - route:
    - destination:
        host: scirs2-core
        subset: standard
      weight: 100
---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: scirs2-core
  namespace: scirs2
spec:
  host: scirs2-core
  subsets:
  - name: high-priority
    labels:
      tier: high-priority
    trafficPolicy:
      connectionPool:
        tcp:
          maxConnections: 100
        http:
          http1MaxPendingRequests: 10
          maxRequestsPerConnection: 2
  - name: standard
    labels:
      tier: standard
    trafficPolicy:
      connectionPool:
        tcp:
          maxConnections: 50
```

### Serverless Deployment

```rust
// AWS Lambda function for serverless SciRS2
use scirs2_core::serverless::{LambdaHandler, ServerlessConfig};
use lambda_runtime::{service_fn, Error, LambdaEvent};

// Configure serverless mode
let serverless_config = ServerlessConfig::new()
    .with_cold_start_optimization(true)
    .with_memory_preallocation(true)
    .with_function_timeout(Duration::from_secs(900));  // 15 minutes

// Lambda handler
#[tokio::main]
async fn main() -> Result<(), Error> {
    let handler = LambdaHandler::new(serverless_config);
    
    lambda_runtime::run(service_fn(|event: LambdaEvent<serde_json::Value>| async move {
        handler.process_event(event).await
    })).await
}

// Serverless computation
impl LambdaHandler {
    async fn process_event(&self, event: LambdaEvent<serde_json::Value>) -> Result<serde_json::Value, Error> {
        // Parse input data
        let input_data: ComputationRequest = serde_json::from_value(event.payload)?;
        
        // Execute computation
        let result = scirs2_core::compute(&input_data.array, &input_data.operation)?;
        
        // Return result
        Ok(serde_json::to_value(ComputationResponse { result })?)
    }
}
```

## Edge Computing

### Edge Node Architecture

```rust
use scirs2_core::edge::{EdgeNode, EdgeConfiguration};

// Configure edge computing node
let edge_config = EdgeConfiguration::new()
    .with_local_compute_limit(4)  // 4 CPU cores
    .with_memory_limit_gb(8)
    .with_cloud_offload_threshold(0.8)  // Offload at 80% utilization
    .with_latency_budget_ms(100)
    .with_bandwidth_limit_mbps(100);

let edge_node = EdgeNode::new(edge_config);

// Intelligent workload distribution
edge_node.on_computation_request(|request| {
    if request.estimated_complexity() > edge_config.local_compute_limit {
        // Offload to cloud
        EdgeDecision::OffloadToCloud
    } else if request.latency_requirement() < edge_config.latency_budget_ms {
        // Process locally
        EdgeDecision::ProcessLocally
    } else {
        // Hybrid processing
        EdgeDecision::HybridProcessing
    }
});
```

### Edge-Cloud Hybrid

```rust
use scirs2_core::hybrid::{HybridOrchestrator, ComputationPartitioner};

// Configure hybrid edge-cloud processing
let orchestrator = HybridOrchestrator::new()
    .with_edge_nodes(vec!["edge1", "edge2", "edge3"])
    .with_cloud_clusters(vec!["cloud-us-east", "cloud-eu-west"])
    .with_cost_optimization(true);

// Partition computation between edge and cloud
let partitioner = ComputationPartitioner::new();
let partition_plan = partitioner.partition_computation(
    &computation_graph,
    &orchestrator.get_available_resources()?
)?;

// Execute hybrid computation
for partition in partition_plan.partitions {
    match partition.target {
        ComputeTarget::Edge(node_id) => {
            orchestrator.execute_on_edge(&node_id, &partition.computation)?;
        },
        ComputeTarget::Cloud(cluster_id) => {
            orchestrator.execute_on_cloud(&cluster_id, &partition.computation)?;
        }
    }
}
```

## Integration Patterns

### API Gateway Integration

```rust
use scirs2_core::integration::{ApiGateway, RateLimiter, Authentication};

// Configure API gateway
let api_gateway = ApiGateway::new()
    .with_rate_limiter(RateLimiter::new()
        .with_requests_per_second(1000)
        .with_burst_capacity(5000))
    .with_authentication(Authentication::JWT {
        secret: "your-jwt-secret".to_string(),
        issuer: "scirs2.com".to_string(),
    })
    .with_request_validation(true)
    .with_response_caching(true);

// Define API routes
api_gateway.route("/api/v1/compute", |request| async move {
    // Validate request
    let computation_request: ComputationRequest = request.validate_json()?;
    
    // Execute computation
    let result = scirs2_core::execute_computation(&computation_request).await?;
    
    // Return response
    Ok(ApiResponse::success(result))
});
```

### Message Queue Integration

```rust
use scirs2_core::integration::{MessageQueue, QueueConfig};

// Configure message queue processing
let queue_config = QueueConfig::new()
    .with_queue_name("scirs2-compute-queue")
    .with_batch_size(10)
    .with_max_wait_time(Duration::from_secs(30))
    .with_retry_policy(RetryPolicy::ExponentialBackoff {
        initial_delay: Duration::from_millis(100),
        max_delay: Duration::from_secs(60),
        max_attempts: 3,
    });

let message_queue = MessageQueue::new("kafka://kafka.scirs2.internal:9092", queue_config);

// Process messages
message_queue.consume(|messages| async move {
    for message in messages {
        let computation_request: ComputationRequest = serde_json::from_slice(&message.payload)?;
        
        // Execute computation
        let result = scirs2_core::execute_computation(&computation_request).await?;
        
        // Send result to output queue
        message_queue.send_result(&result, &message.reply_to).await?;
    }
    Ok(())
});
```

### Database Integration

```rust
use scirs2_core::integration::{DatabaseConnector, QueryOptimizer};

// Configure database integration
let db_connector = DatabaseConnector::new("postgresql://scirs2:password@db.scirs2.internal/scirs2")
    .with_connection_pool_size(10)
    .with_query_timeout(Duration::from_secs(30))
    .with_read_replicas(vec!["db-replica-1", "db-replica-2"]);

// Optimized data loading
let query_optimizer = QueryOptimizer::new();
let optimized_query = query_optimizer.optimize_for_computation(
    "SELECT * FROM large_dataset WHERE created_at > $1",
    &computation_requirements
)?;

// Stream data for processing
let data_stream = db_connector.stream_query_results(&optimized_query)?;
let result = scirs2_core::process_stream(data_stream, |batch| {
    // Process each batch
    scirs2_core::compute_statistics(&batch)
}).await?;
```

## Migration Strategies

### Legacy System Migration

```rust
use scirs2_core::migration::{LegacyAdapter, MigrationPlan};

// Create adapter for legacy systems
let legacy_adapter = LegacyAdapter::new()
    .with_source_system("legacy-matlab-system")
    .with_data_format_conversion(true)
    .with_api_translation(true);

// Define migration plan
let migration_plan = MigrationPlan::new()
    .add_phase(MigrationPhase::new("assessment")
        .with_duration(Duration::from_days(7))
        .with_tasks(vec![
            "Analyze legacy codebase",
            "Identify critical functions",
            "Map data dependencies",
        ]))
    .add_phase(MigrationPhase::new("parallel_deployment")
        .with_duration(Duration::from_days(30))
        .with_tasks(vec![
            "Deploy SciRS2 alongside legacy system",
            "Implement data synchronization",
            "Gradual traffic migration",
        ]))
    .add_phase(MigrationPhase::new("validation")
        .with_duration(Duration::from_days(14))
        .with_tasks(vec![
            "Validate computation results",
            "Performance benchmarking",
            "User acceptance testing",
        ]))
    .add_phase(MigrationPhase::new("cutover")
        .with_duration(Duration::from_days(3))
        .with_tasks(vec![
            "Final data migration",
            "DNS switchover",
            "Legacy system decommission",
        ]));

// Execute migration
migration_plan.execute_with_rollback_capability()?;
```

### Zero-Downtime Migration

```rust
use scirs2_core::migration::{ZeroDowntimeMigrator, TrafficSplitter};

// Configure zero-downtime migration
let migrator = ZeroDowntimeMigrator::new()
    .with_health_checks(true)
    .with_rollback_threshold(0.05)  // Rollback if error rate > 5%
    .with_canary_percentage(10);    // Start with 10% traffic

// Configure traffic splitting
let traffic_splitter = TrafficSplitter::new()
    .with_legacy_system("legacy.scirs2.internal")
    .with_new_system("new.scirs2.internal")
    .with_result_comparison(true);

// Gradual migration with monitoring
migrator.migrate_gradually(
    traffic_splitter,
    vec![10, 25, 50, 75, 100],  // Traffic percentages
    Duration::from_hours(24),   // Time between increases
)?;
```

### Data Migration

```rust
use scirs2_core::migration::{DataMigrator, DataValidator};

// Configure data migration
let data_migrator = DataMigrator::new()
    .with_source("legacy-database")
    .with_target("scirs2-database")
    .with_batch_size(10000)
    .with_validation(true)
    .with_checkpoint_interval(Duration::from_minutes(10));

// Validate data integrity
let data_validator = DataValidator::new()
    .with_checksum_validation(true)
    .with_statistical_validation(true)
    .with_sample_validation(0.1);  // Validate 10% of records

// Execute migration with validation
let migration_result = data_migrator.migrate_with_validation(
    &data_validator,
    |progress| {
        println!("Migration progress: {:.1}%", progress.percentage_complete);
    }
)?;

println!("Migration completed: {} records migrated", migration_result.records_migrated);
println!("Validation errors: {}", migration_result.validation_errors.len());
```

---

**Version**: SciRS2 Core 1.0  
**Last Updated**: 2025-06-29  
**Authors**: SciRS2 Architecture Team  
**License**: See LICENSE file for details