# LakeLogic Streaming Implementation Status

## ✅ **Completed (Architecture & Design)**

### **1. Architecture Design**
- ✅ Medallion architecture with REALTIME layer
- ✅ Bronze = Complete history (append-only)
- ✅ Realtime = Materialized views (current only)
- ✅ Silver = Cleaned data (batch)
- ✅ Gold = Business metrics (batch)

### **2. Contract Schema Design**
- ✅ Streaming source configuration
- ✅ Realtime aggregations
- ✅ Automatic framework selection (Bytewax vs Pathway)
- ✅ Retention policies
- ✅ Windowing configuration

### **3. Documentation**
- ✅ `docs/streaming_test_providers.md` - 10+ public streaming datasets
- ✅ `docs/database_cdc.md` - Database CDC guide
- ✅ Contract examples (Azure SQL CDC, REST API)
- ✅ Architecture diagrams

### **4. Dependencies**
- ✅ Added to `pyproject.toml`:
  - Database connectors (azuresql, postgresql, mysql, mongodb)
  - Integration connectors (api, sftp, messaging)
  - Cloud authentication (Azure, AWS, GCP)
  - Key Vault support

### **5. Existing Implementations**
- ✅ `cloud_credentials.py` - Automatic credential resolution + Key Vault support
- ✅ `database_connectors.py` - Azure SQL, PostgreSQL CDC
- ✅ `integration_connectors.py` - REST API, SFTP, Service Bus
- ✅ `delta_adapter.py` - Spark-free Delta Lake operations

---

## 🔄 **Not Yet Implemented (Streaming Core)**

### **1. Streaming Framework Integration**
- ❌ Bytewax integration
- ❌ Pathway integration
- ❌ Automatic framework selector
- ❌ SSE (Server-Sent Events) connector
- ❌ WebSocket connector

### **2. Streaming Connectors**
- ❌ Kafka connector
- ❌ Azure Event Grid connector
- ❌ AWS SQS/SNS connector
- ❌ GCP Pub/Sub connector

### **3. Streaming DataProcessor**
- ❌ `mode="streaming"` support
- ❌ Real-time aggregations
- ❌ Windowing (tumbling, sliding, session)
- ❌ Watermarking (late data handling)
- ❌ Checkpointing

### **4. Realtime Layer**
- ❌ Automatic retention management
- ❌ Materialized view updates
- ❌ Dual-write (Bronze + Realtime)

### **5. Examples**
- ❌ Wikimedia stream example
- ❌ Coinbase WebSocket example
- ❌ Complete streaming pipeline example

---

## 🎯 **Implementation Priority**

### **Phase 1: Core Streaming (High Priority)**

#### **1.1 Add Streaming Dependencies**
```toml
# pyproject.toml
streaming = [
    "bytewax>=0.19.0",
    "pathway>=0.7.0",
]
sse = ["sseclient-py>=1.7.2"]  # For Wikimedia
websocket = ["websocket-client>=1.6.0"]  # For Coinbase
```

#### **1.2 Create SSE Connector**
```python
# lakelogic/engines/streaming_connectors.py
class SSEConnector:
    """Server-Sent Events connector (Wikimedia, etc.)"""
    
    def __init__(self, url: str):
        self.url = url
    
    def stream(self):
        """Yield events from SSE stream"""
        import sseclient
        import requests
        
        response = requests.get(self.url, stream=True)
        client = sseclient.SSEClient(response)
        
        for event in client.events():
            if event.data:
                yield json.loads(event.data)
```

#### **1.3 Create WebSocket Connector**
```python
# lakelogic/engines/streaming_connectors.py
class WebSocketConnector:
    """WebSocket connector (Coinbase, Binance, etc.)"""
    
    def __init__(self, url: str, subscribe_message: dict):
        self.url = url
        self.subscribe_message = subscribe_message
    
    def stream(self):
        """Yield events from WebSocket"""
        import websocket
        
        ws = websocket.WebSocketApp(
            self.url,
            on_message=lambda ws, msg: self._on_message(msg)
        )
        
        # Send subscribe message
        ws.on_open = lambda ws: ws.send(json.dumps(self.subscribe_message))
        
        ws.run_forever()
```

#### **1.4 Create Streaming DataProcessor**
```python
# lakelogic/core/streaming_processor.py
class StreamingDataProcessor:
    """
    Process streaming data with contracts.
    """
    
    def __init__(self, contract: str, framework: str = "auto"):
        self.contract = load_contract(contract)
        self.framework = self._select_framework(framework)
    
    def start(self):
        """Start streaming pipeline"""
        if self.framework == "bytewax":
            self._start_bytewax()
        elif self.framework == "pathway":
            self._start_pathway()
    
    def _start_bytewax(self):
        """Start Bytewax pipeline"""
        from bytewax.dataflow import Dataflow
        
        flow = Dataflow()
        
        # 1. Input from source
        flow.input("source", self._create_input())
        
        # 2. Validate schema
        flow.map(lambda x: self._validate_schema(x))
        
        # 3. Apply transformations
        flow.map(lambda x: self._apply_transformations(x))
        
        # 4. Validate quality
        flow.map(lambda x: self._validate_quality(x))
        
        # 5. Write to Bronze
        flow.output("bronze", self._write_bronze)
        
        # 6. Create realtime aggregations
        for agg in self.contract.get("realtime", []):
            self._create_aggregation(flow, agg)
```

---

### **Phase 2: Examples (Medium Priority)**

#### **2.1 Wikimedia Example**
```python
# examples/streaming/wikimedia_example.py
from lakelogic import DataProcessor

processor = DataProcessor(
    contract="examples/streaming/wikimedia_contract.yaml",
    mode="streaming"
)

processor.start()
```

#### **2.2 Coinbase Example**
```python
# examples/streaming/coinbase_example.py
from lakelogic import DataProcessor

processor = DataProcessor(
    contract="examples/streaming/coinbase_contract.yaml",
    mode="streaming"
)

processor.start()
```

---

### **Phase 3: Advanced Features (Lower Priority)**

- ❌ Exactly-once semantics
- ❌ Backpressure handling
- ❌ State management
- ❌ Monitoring & observability
- ❌ Auto-scaling

---

## 📊 **Current Status Summary**

| Component | Status | Completion |
|-----------|--------|------------|
| **Architecture** | ✅ Complete | 100% |
| **Documentation** | ✅ Complete | 100% |
| **Contracts** | ✅ Complete | 100% |
| **Dependencies** | ✅ Added | 100% |
| **Batch Processing** | ✅ Complete | 100% |
| **Database CDC** | ✅ Complete | 100% |
| **API Connectors** | ✅ Complete | 100% |
| **Cloud Auth** | ✅ Complete | 100% |
| **Key Vault** | ✅ Complete | 100% |
| **Streaming Core** | ❌ Not Started | 0% |
| **Streaming Connectors** | ❌ Not Started | 0% |
| **Realtime Layer** | ❌ Not Started | 0% |
| **Examples** | ❌ Not Started | 0% |

---

## 🚀 **Next Steps**

### **Immediate (Next Session)**
1. Add Bytewax and Pathway to `pyproject.toml`
2. Create `streaming_connectors.py` (SSE, WebSocket)
3. Create `streaming_processor.py` (core streaming logic)
4. Create Wikimedia example (simplest test case)

### **Short-Term (Next Week)**
1. Implement automatic framework selection
2. Add Kafka connector
3. Create Coinbase example
4. Add realtime layer management

### **Medium-Term (Next Month)**
1. Add Azure Event Grid, Service Bus connectors
2. Add AWS SQS/SNS connectors
3. Add GCP Pub/Sub connector
4. Complete documentation

---

## 💡 **Key Insights from Design Phase**

1. **Realtime ≠ Gold** - Materialized views should be in separate `realtime/` layer
2. **Bronze = History** - Complete history stored once in Bronze (append-only)
3. **Auto-Selection** - Framework selection should be automatic based on contract
4. **Dual-Write** - Stream to both Bronze (history) and Realtime (current)
5. **Retention** - Realtime tables have automatic retention policies

---

## 🎯 **Success Criteria**

### **Minimum Viable Streaming (MVS)**
- ✅ SSE connector (Wikimedia)
- ✅ Bytewax integration
- ✅ Bronze + Realtime dual-write
- ✅ Basic aggregations (tumbling windows)
- ✅ One working example (Wikimedia)

### **Production-Ready Streaming**
- ✅ All connectors (SSE, WebSocket, Kafka, messaging)
- ✅ Both frameworks (Bytewax + Pathway)
- ✅ Automatic framework selection
- ✅ Complete realtime layer management
- ✅ Multiple examples
- ✅ Monitoring & observability

---

*Status as of: February 9, 2026*
