HTTP Client

The Milvus SDK provides both gRPC and HTTP clients. This guide covers the HTTP client and when to use it.

HttpClient vs MilvusClient

• MilvusClient: Uses gRPC protocol (default, recommended)
• HttpClient: Uses HTTP/REST protocol

When to Use HTTP Client

Use HTTP client when:

• You need HTTP/REST compatibility
• Working behind firewalls that block gRPC
• Integrating with systems that prefer HTTP
• Using serverless environments (Vercel, Cloudflare Workers, AWS Lambda, etc.) - Highly recommended

Creating HTTP Client

import { HttpClient } from '@zilliz/milvus2-sdk-node';

const client = new HttpClient({
  endpoint: 'http://localhost:19530',
  token: 'your-token', // Optional
});

HTTP client requests use camelCase field names such as collectionName, dbName, and outputFields. The gRPC MilvusClient uses snake_case names such as collection_name and output_fields.

Using HTTP Client in Serverless Environments

Why HTTP Client for Serverless?

gRPC limitations in serverless platforms:

1. Connection persistence: gRPC relies on long-lived TCP connections, but serverless functions are stateless and short-lived. Each invocation may run in a different container/environment, making connection reuse impossible.

2. Cold starts: Serverless functions start from scratch on each cold start. gRPC connection establishment overhead adds significant latency to cold starts.

3. Network restrictions: Many serverless platforms (especially Cloudflare Workers) don’t support raw TCP connections required by gRPC. They only support HTTP/HTTPS protocols.

4. Timeout constraints: Serverless platforms have strict execution time limits. gRPC’s connection setup and keep-alive mechanisms can consume valuable execution time.

5. Resource constraints: Serverless environments have limited resources. gRPC’s connection pooling and multiplexing overhead can be problematic in constrained environments.

HTTP Client advantages:

• Stateless: Each request is independent, perfect for serverless functions
• Universal support: HTTP/HTTPS is supported by all serverless platforms
• No connection overhead: No need to maintain persistent connections
• Better cold start performance: Faster initialization without connection setup
• Simpler error handling: Standard HTTP status codes and error responses

Vercel Example

// api/search.js (Vercel Serverless Function)
import { HttpClient } from '@zilliz/milvus2-sdk-node';

let client;

function getClient() {
  if (!client) {
    client = new HttpClient({
      baseURL: process.env.MILVUS_ENDPOINT, // e.g., 'https://your-instance.zillizcloud.com'
      token: process.env.MILVUS_TOKEN,
      timeout: 10000, // Adjust based on Vercel's timeout limits
    });
  }
  return client;
}

export default async function handler(req, res) {
  try {
    const milvusClient = getClient();

    const results = await milvusClient.search({
      collectionName: 'my_collection',
      data: [req.body.vector],
      limit: 10,
    });

    res.status(200).json({ results });
  } catch (error) {
    console.error('Milvus error:', error);
    res.status(500).json({ error: error.message });
  }
}

Vercel configuration (vercel.json):

{
  "functions": {
    "api/search.js": {
      "maxDuration": 30
    }
  },
  "env": {
    "MILVUS_ENDPOINT": "https://your-instance.zillizcloud.com",
    "MILVUS_TOKEN": "your-token"
  }
}

Cloudflare Workers Example

// worker.js (Cloudflare Worker)
import { HttpClient } from '@zilliz/milvus2-sdk-node';

export default {
  async fetch(request, env) {
    // Cloudflare Workers only support HTTP/HTTPS, not raw TCP
    // HTTP Client is the only option here
    const client = new HttpClient({
      baseURL: env.MILVUS_ENDPOINT,
      token: env.MILVUS_TOKEN,
      timeout: 10000, // Cloudflare Workers have 30s timeout for free tier
    });

    try {
      const body = await request.json();

      const results = await client.search({
        collectionName: 'my_collection',
        data: [body.vector],
        limit: 10,
      });

      return new Response(JSON.stringify({ results }), {
        headers: { 'Content-Type': 'application/json' },
      });
    } catch (error) {
      return new Response(JSON.stringify({ error: error.message }), {
        status: 500,
        headers: { 'Content-Type': 'application/json' },
      });
    }
  },
};

Cloudflare Workers configuration (wrangler.toml):

name = "milvus-worker"
main = "worker.js"
compatibility_date = "2024-01-01"

[vars]
MILVUS_ENDPOINT = "https://your-instance.zillizcloud.com"
MILVUS_TOKEN = "your-token"

AWS Lambda Example

// lambda.js (AWS Lambda)
import { HttpClient } from '@zilliz/milvus2-sdk-node';

let client;

function getClient() {
  if (!client) {
    client = new HttpClient({
      baseURL: process.env.MILVUS_ENDPOINT,
      token: process.env.MILVUS_TOKEN,
      timeout: 25000, // Leave buffer for Lambda timeout
    });
  }
  return client;
}

export const handler = async (event) => {
  try {
    const milvusClient = getClient();

    const results = await milvusClient.search({
      collectionName: 'my_collection',
      data: [event.vector],
      limit: 10,
    });

    return {
      statusCode: 200,
      body: JSON.stringify({ results }),
    };
  } catch (error) {
    console.error('Milvus error:', error);
    return {
      statusCode: 500,
      body: JSON.stringify({ error: error.message }),
    };
  }
};

Serverless Best Practices

1. Client reuse: Reuse the client instance within the same execution context (using module-level variable or singleton pattern)

2. Timeout configuration: Set appropriate timeouts based on your platform’s limits:

   • Vercel: 10s (Hobby), 60s (Pro)
   • Cloudflare Workers: 30s (free), 30s-15min (paid)
   • AWS Lambda: Up to 15 minutes

3. Error handling: Always wrap operations in try-catch blocks and return appropriate HTTP responses

4. Environment variables: Store credentials securely using platform-specific secret management

5. Connection pooling: Not needed with HTTP client - each request is independent

6. Cold start optimization: HTTP client initializes faster than gRPC client, reducing cold start impact

Collection Operations

Create Collection

await client.createCollection({
  collectionName: 'my_collection',
  dimension: 128,
  metricType: 'L2',
});

List Collections

const collections = await client.listCollections({
  dbName: 'default',
});

console.log('Collections:', collections);

Describe Collection

const info = await client.describeCollection({
  collectionName: 'my_collection',
});

console.log('Collection info:', info);

Drop Collection

await client.dropCollection({
  collectionName: 'my_collection',
});

Vector Operations

Insert Vectors

await client.insert({
  collectionName: 'my_collection',
  data: [
    {
      id: 1,
      vector: [0.1, 0.2, 0.3, 0.4],
    },
  ],
});

Search Vectors

const results = await client.search({
  collectionName: 'my_collection',
  data: [[0.1, 0.2, 0.3, 0.4]],
  limit: 10,
});

Query Vectors

const results = await client.query({
  collectionName: 'my_collection',
  filter: 'age > 25',
  outputFields: ['id', 'vector'],
});

Delete Vectors

await client.delete({
  collectionName: 'my_collection',
  filter: 'id in [1, 2, 3]',
});

Index Operations

Create Index

await client.createIndex({
  collectionName: 'my_collection',
  indexParams: [
    {
      fieldName: 'vector',
      indexName: 'vector_idx',
      metricType: 'L2',
      params: { index_type: 'HNSW' },
    },
  ],
});

Describe Index

const index = await client.describeIndex({
  collectionName: 'my_collection',
  indexName: 'vector_idx',
});

console.log('Index info:', index);

List Indexes

const indexes = await client.listIndexes({
  collectionName: 'my_collection',
});

console.log('Indexes:', indexes);

Drop Index

await client.dropIndex({
  collectionName: 'my_collection',
  indexName: 'vector_idx',
});

Partition Operations

Create Partition

await client.createPartition({
  collectionName: 'my_collection',
  partitionName: 'partition_1',
});

List Partitions

const partitions = await client.listPartitions({
  collectionName: 'my_collection',
});

console.log('Partitions:', partitions);

Drop Partition

await client.dropPartition({
  collectionName: 'my_collection',
  partitionName: 'partition_1',
});

Alias Operations

Create Alias

await client.createAlias({
  collectionName: 'my_collection',
  aliasName: 'my_alias',
});

List Aliases

const aliases = await client.listAliases({
  collectionName: 'my_collection',
});

console.log('Aliases:', aliases);

Drop Alias

await client.dropAlias({
  aliasName: 'my_alias',
});

Import Operations

Import Data

const result = await client.createImportJobs({
  collectionName: 'my_collection',
  files: [['imports/data.json']],
});

console.log('Import task:', result);

User Operations

Create User

await client.createUser({
  userName: 'newuser',
  password: 'password',
});

List Users

const users = await client.listUsers();

console.log('Users:', users);

Role Operations

Create Role

await client.createRole({
  roleName: 'admin',
});

List Roles

const roles = await client.listRoles();

console.log('Roles:', roles);

HTTP Client Configuration

const client = new HttpClient({
  endpoint: 'http://localhost:19530',
  token: 'your-token',
  timeout: 30000,
});

Error Handling

HTTP client errors follow the same pattern as gRPC client:

try {
  await client.createCollection({
    /* ... */
  });
} catch (error) {
  console.error('Error:', error.message);
  console.error('Status:', error.status);
}

Best Practices

1. Choose the right client: Use gRPC for better performance, HTTP for compatibility
2. Error handling: Always handle errors appropriately
3. Timeout configuration: Set appropriate timeouts
4. Authentication: Use tokens for secure connections

Next Steps

• Learn about MilvusClient (gRPC client)
• Explore Best Practices
• Check out Examples & Tutorials