Add data processing microservice with API endpoints and tests

Co-authored-by: axellab <38169843+axellab@users.noreply.github.com>

Author: Copilot

DATA_PROCESSING_SERVICE.md

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+# Data Processing Microservice
+
+A microservice for processing and transforming information that can connect with other services.
+
+## Overview
+
+The Data Processing Microservice provides REST API endpoints for transforming and processing data in various ways. It supports operations like uppercase/lowercase transformations, filtering, mapping, and aggregation.
+
+## API Endpoints
+
+### Health Check
+- **GET** `/rest/data-processing/health`
+- Returns the health status of the microservice
+- Response:
+  ```json
+  {
+    "status": "healthy",
+    "service": "data-processing",
+    "timestamp": "2025-11-12T05:19:19.721Z"
+  }
+  ```
+
+### Get Available Operations
+- **GET** `/rest/data-processing/operations`
+- Returns a list of all available operations with descriptions and examples
+- Response:
+  ```json
+  {
+    "status": "success",
+    "operations": [...]
+  }
+  ```
+
+### Process Data
+- **POST** `/rest/data-processing/process`
+- Processes and transforms data based on the specified operation
+- Request Body:
+  ```json
+  {
+    "operation": "uppercase|lowercase|filter|map|aggregate",
+    "data": "any",
+    "options": {}
+  }
+  ```
+- Response:
+  ```json
+  {
+    "status": "success",
+    "result": "transformed data"
+  }
+  ```
+
+### Process Multiple Sources
+- **POST** `/rest/data-processing/process-multiple`
+- Combines and processes data from multiple sources
+- Request Body:
+  ```json
+  {
+    "sources": [
+      { "name": "source1", "data": {...} },
+      { "name": "source2", "data": {...} }
+    ]
+  }
+  ```
+
+## Operations
+
+### Uppercase
+Transforms string data to uppercase. Works with strings, arrays, and objects.
+
+**Example:**
+```json
+{
+  "operation": "uppercase",
+  "data": "hello world"
+}
+```
+**Result:** `"HELLO WORLD"`
+
+### Lowercase
+Transforms string data to lowercase. Works with strings, arrays, and objects.
+
+**Example:**
+```json
+{
+  "operation": "lowercase",
+  "data": "HELLO WORLD"
+}
+```
+**Result:** `"hello world"`
+
+### Filter
+Filters array data based on conditions.
+
+**Example:**
+```json
+{
+  "operation": "filter",
+  "data": [
+    { "name": "John", "age": 30 },
+    { "name": "Jane", "age": 25 }
+  ],
+  "options": {
+    "conditions": { "age": 30 }
+  }
+}
+```
+**Result:** `[{ "name": "John", "age": 30 }]`
+
+### Map
+Maps array data to specific fields.
+
+**Example:**
+```json
+{
+  "operation": "map",
+  "data": [
+    { "name": "John", "age": 30, "city": "NYC" }
+  ],
+  "options": {
+    "fields": ["name", "age"]
+  }
+}
+```
+**Result:** `[{ "name": "John", "age": 30 }]`
+
+### Aggregate
+Aggregates array data with optional grouping.
+
+**Example:**
+```json
+{
+  "operation": "aggregate",
+  "data": [
+    { "category": "A", "value": 10 },
+    { "category": "A", "value": 20 },
+    { "category": "B", "value": 15 }
+  ],
+  "options": {
+    "groupBy": "category",
+    "sumFields": ["value"]
+  }
+}
+```
+**Result:**
+```json
+[
+  { "category": "A", "value": 30 },
+  { "category": "B", "value": 15 }
+]
+```
+
+## Architecture
+
+The microservice is composed of two main modules:
+
+1. **lib/dataProcessing.ts** - Core processing logic
+   - Data transformation functions
+   - Validation logic
+   - Processing algorithms
+
+2. **routes/dataProcessing.ts** - REST API handlers
+   - Express route handlers
+   - Request validation
+   - Response formatting
+
+## Integration
+
+The microservice is integrated into the OWASP Juice Shop application through the main server.ts file. The routes are registered under the `/rest/data-processing` path.
+
+## Testing
+
+Tests are located in:
+- `test/api/dataProcessingSpec.ts` - API integration tests
+- `test/server/dataProcessingSpec.ts` - Unit tests
+
+Run tests with:
+```bash
+npm test
+```
+
+## Usage Examples
+
+### Using curl
+
+```bash
+# Health check
+curl http://localhost:3000/rest/data-processing/health
+
+# Transform to uppercase
+curl -X POST http://localhost:3000/rest/data-processing/process \
+  -H "Content-Type: application/json" \
+  -d '{"operation": "uppercase", "data": "hello world"}'
+
+# Filter data
+curl -X POST http://localhost:3000/rest/data-processing/process \
+  -H "Content-Type: application/json" \
+  -d '{
+    "operation": "filter",
+    "data": [{"name": "John", "age": 30}, {"name": "Jane", "age": 25}],
+    "options": {"conditions": {"age": 30}}
+  }'
+```
+
+### Using JavaScript/TypeScript
+
+```typescript
+// Example using fetch
+const response = await fetch('http://localhost:3000/rest/data-processing/process', {
+  method: 'POST',
+  headers: {
+    'Content-Type': 'application/json'
+  },
+  body: JSON.stringify({
+    operation: 'uppercase',
+    data: 'hello world'
+  })
+});
+
+const result = await response.json();
+console.log(result.result); // "HELLO WORLD"
+```
+
+## Error Handling
+
+The microservice returns appropriate HTTP status codes:
+- `200` - Success
+- `400` - Bad request (invalid input)
+- `500` - Internal server error
+
+Error responses follow this format:
+```json
+{
+  "status": "error",
+  "error": "Error message"
+}
+```
+
+## Future Enhancements
+
+Possible future enhancements include:
+- Additional transformation operations
+- Batch processing capabilities
+- Data validation operations
+- Format conversion (JSON to XML, CSV, etc.)
+- Scheduled processing jobs
+- Webhook support for async processing