Knowledge Graph Module

Overview

The Knowledge Graph Module is a critical component of PDeck that maintains a structured representation of relationships between tasks, users, projects, and other relevant entities. It provides context for task prioritization, enables intelligent task management, and facilitates advanced features like dependency tracking and impact analysis.

Key Responsibilities

Maintain a graph structure of entities and their relationships
Update the graph based on user actions and system events
Provide APIs for querying relationships and context
Support the Task Prioritization Engine with contextual information
Enable advanced features like impact analysis and intelligent task suggestions

Technology Stack

Node.js for the core implementation
Neo4j graph database for storing and querying the knowledge graph
Redis for caching frequently accessed graph data

Implementation Guidelines

1. Setting Up the Knowledge Graph Module

Create a new module for the Knowledge Graph:

// services/knowledgeGraphService.js
const neo4j = require('neo4j-driver')
const redis = require('redis')
const { promisify } = require('util')
 
class KnowledgeGraphService {
  constructor() {
    this.driver = neo4j.driver(
      process.env.NEO4J_URI,
      neo4j.auth.basic(process.env.NEO4J_USER, process.env.NEO4J_PASSWORD)
    )
    this.redisClient = redis.createClient(process.env.REDIS_URL)
    this.getAsync = promisify(this.redisClient.get).bind(this.redisClient)
    this.setAsync = promisify(this.redisClient.set).bind(this.redisClient)
  }
 
  async getSession() {
    return this.driver.session()
  }
 
  // ... (other methods)
}
 
module.exports = new KnowledgeGraphService()

2. Implementing Basic CRUD Operations

Create methods for adding, updating, and deleting nodes and relationships:

class KnowledgeGraphService {
  // ... (previous code)
 
  async createNode(label, properties) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `CREATE (n:${label} $props) RETURN n`,
        { props: properties }
      )
      return result.records[0].get('n').properties
    } finally {
      await session.close()
    }
  }
 
  async updateNode(label, id, properties) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (n:${label} {id: $id})
         SET n += $props
         RETURN n`,
        { id, props: properties }
      )
      return result.records[0].get('n').properties
    } finally {
      await session.close()
    }
  }
 
  async deleteNode(label, id) {
    const session = await this.getSession()
    try {
      await session.run(
        `MATCH (n:${label} {id: $id})
         DETACH DELETE n`,
        { id }
      )
    } finally {
      await session.close()
    }
  }
 
  async createRelationship(fromLabel, fromId, toLabel, toId, relationType, properties = {}) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (a:${fromLabel} {id: $fromId}), (b:${toLabel} {id: $toId})
         CREATE (a)-[r:${relationType} $props]->(b)
         RETURN r`,
        { fromId, toId, props: properties }
      )
      return result.records[0].get('r').properties
    } finally {
      await session.close()
    }
  }
 
  async deleteRelationship(fromLabel, fromId, toLabel, toId, relationType) {
    const session = await this.getSession()
    try {
      await session.run(
        `MATCH (a:${fromLabel} {id: $fromId})-[r:${relationType}]->(b:${toLabel} {id: $toId})
         DELETE r`,
        { fromId, toId }
      )
    } finally {
      await session.close()
    }
  }
}

3. Implementing Query Methods

Create methods for querying the knowledge graph:

class KnowledgeGraphService {
  // ... (previous code)
 
  async getRelatedTasks(taskId) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (t:Task {id: $taskId})-[r]-(relatedTask:Task)
         RETURN relatedTask, type(r) as relationType`,
        { taskId }
      )
      return result.records.map(record => ({
        task: record.get('relatedTask').properties,
        relationType: record.get('relationType')
      }))
    } finally {
      await session.close()
    }
  }
 
  async getTaskDependencies(taskId) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (t:Task {id: $taskId})-[:DEPENDS_ON]->(dependencyTask:Task)
         RETURN dependencyTask`,
        { taskId }
      )
      return result.records.map(record => record.get('dependencyTask').properties)
    } finally {
      await session.close()
    }
  }
 
  async getUserContextForTask(userId, taskId) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (u:User {id: $userId})-[r]-(t:Task {id: $taskId})
         RETURN type(r) as relationType, t as task`,
        { userId, taskId }
      )
      return result.records.map(record => ({
        relationType: record.get('relationType'),
        task: record.get('task').properties
      }))
    } finally {
      await session.close()
    }
  }
}

4. Implementing Caching

Use Redis to cache frequently accessed graph data:

class KnowledgeGraphService {
  // ... (previous code)
 
  async getCachedOrFetch(key, fetchFn) {
    const cachedData = await this.getAsync(key)
    if (cachedData) {
      return JSON.parse(cachedData)
    }
 
    const data = await fetchFn()
    await this.setAsync(key, JSON.stringify(data), 'EX', 300) // Cache for 5 minutes
    return data
  }
 
  async getRelatedTasksCached(taskId) {
    return this.getCachedOrFetch(`related_tasks:${taskId}`, () => this.getRelatedTasks(taskId))
  }
 
  async getTaskDependenciesCached(taskId) {
    return this.getCachedOrFetch(`task_dependencies:${taskId}`, () => this.getTaskDependencies(taskId))
  }
 
  async invalidateCache(key) {
    await this.redisClient.del(key)
  }
}

5. Implementing Graph Update Methods

Create methods to update the graph based on system events:

class KnowledgeGraphService {
  // ... (previous code)
 
  async addTask(task, userId) {
    const taskNode = await this.createNode('Task', task)
    await this.createRelationship('User', userId, 'Task', task.id, 'OWNS')
    return taskNode
  }
 
  async updateTask(task) {
    return this.updateNode('Task', task.id, task)
  }
 
  async deleteTask(taskId) {
    await this.deleteNode('Task', taskId)
    await this.invalidateCache(`related_tasks:${taskId}`)
    await this.invalidateCache(`task_dependencies:${taskId}`)
  }
 
  async addTaskDependency(taskId, dependencyTaskId) {
    await this.createRelationship('Task', taskId, 'Task', dependencyTaskId, 'DEPENDS_ON')
    await this.invalidateCache(`task_dependencies:${taskId}`)
  }
 
  async removeTaskDependency(taskId, dependencyTaskId) {
    await this.deleteRelationship('Task', taskId, 'Task', dependencyTaskId, 'DEPENDS_ON')
    await this.invalidateCache(`task_dependencies:${taskId}`)
  }
 
  async addUserToProject(userId, projectId) {
    await this.createRelationship('User', userId, 'Project', projectId, 'MEMBER_OF')
  }
}

6. Implementing Advanced Query Methods

Create methods for advanced graph queries:

class KnowledgeGraphService {
  // ... (previous code)
 
  async getImpactAnalysis(taskId) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (t:Task {id: $taskId})<-[:DEPENDS_ON*]-(impactedTask:Task)
         RETURN impactedTask`,
        { taskId }
      )
      return result.records.map(record => record.get('impactedTask').properties)
    } finally {
      await session.close()
    }
  }
 
  async suggestRelatedTasks(userId, taskId) {
    const session = await this.getSession()
    try {
      const result = await session.run(
        `MATCH (u:User {id: $userId})-[:OWNS]->(t:Task {id: $taskId})
         MATCH (u)-[:OWNS]->(otherTask:Task)
         WHERE otherTask.id <> $taskId
         AND (otherTask.project = t.project OR otherTask.tags = t.tags)
         RETURN otherTask, count(*) as relevance
         ORDER BY relevance DESC
         LIMIT 5`,
        { userId, taskId }
      )
      return result.records.map(record => record.get('otherTask').properties)
    } finally {
      await session.close()
    }
  }
}

Best Practices

Use parameterized queries to prevent Cypher injection attacks.
Implement proper error handling and logging for all graph operations.
Use transactions for operations that involve multiple graph updates.
Regularly backup the Neo4j database to prevent data loss.
Monitor query performance and optimize as necessary.
Implement a robust caching strategy to reduce load on the graph database.
Use appropriate indexes in Neo4j to speed up common queries.

Next Steps

Implement more advanced graph algorithms (e.g., centrality measures, community detection) for task analysis.
Develop a system to infer task relationships based on user behavior and task content.
Create visualizations of the knowledge graph to help users understand task relationships.
Implement natural language processing to extract entities and relationships from task descriptions.
Develop an API for other services to query and update the knowledge graph.
Implement versioning for the knowledge graph to track changes over time.
Create a dashboard for monitoring the health and growth of the knowledge graph.

Asynchronous Processing Task Prioritization Engine