Supported Protocols

WSO2 Integrator, powered by Ballerina, provides native support for a wide range of communication protocols used in integration scenarios. Each protocol is implemented as a Ballerina module with type-safe clients, listeners, and services.

HTTP and web protocols

Protocol	Module	Description	Key Features
HTTP/1.1	ballerina/http	Standard HTTP protocol	REST APIs, content negotiation, compression, caching
HTTP/2	ballerina/http	Multiplexed HTTP protocol	Server push, stream prioritization, header compression
WebSocket	ballerina/websocket	Full-duplex communication over TCP	Real-time messaging, binary and text frames, ping/pong
WebSub	ballerina/websub, ballerina/websubhub	W3C WebSub pub/sub protocol	Content distribution, webhook-based subscriptions
GraphQL	ballerina/graphql	GraphQL query language protocol	Queries, mutations, subscriptions, schema introspection
gRPC	ballerina/grpc	Google Remote Procedure Call	Unary, server streaming, client streaming, bidirectional streaming

HTTP example

import ballerina/http;

// HTTP/1.1 service
service /api on new http:Listener(8080) {
    resource function get greeting() returns string {
        return "Hello, World!";
    }
}

// HTTP/2 client
http:Client http2Client = check new ("https://api.example.com", {
    httpVersion: http:HTTP_2_0
});

Messaging protocols

Protocol	Module	Description	Key Features
Apache Kafka	ballerinax/kafka	Distributed event streaming	Producer, consumer, consumer groups, topic management
RabbitMQ	ballerinax/rabbitmq	AMQP messaging broker	Exchanges, queues, bindings, message acknowledgment
MQTT	ballerinax/mqtt	Lightweight IoT messaging	QoS levels, retained messages, last will, topic wildcards
NATS	ballerinax/nats	Cloud-native messaging	Pub/sub, request/reply, queue groups
NATS Streaming	ballerinax/stan	Streaming extension for NATS	Durable subscriptions, message replay, at-least-once delivery
JMS	ballerinax/java.jms	Java Message Service	Queues, topics, durable subscribers, message selectors
Azure Service Bus	ballerinax/asb	Azure cloud messaging	Queues, topics, sessions, dead-letter queues

Kafka example

import ballerinax/kafka;

kafka:Producer producer = check new ("localhost:9092");

check producer->send({
    topic: "orders",
    value: {orderId: "ORD-001", amount: 99.99}
});

// Consumer
kafka:Consumer consumer = check new ("localhost:9092", {
    groupId: "order-processors",
    topics: ["orders"]
});

kafka:ConsumerRecord[] records = check consumer->poll(1);

Transport protocols

Protocol	Module	Description	Key Features
TCP	ballerina/tcp	Transmission Control Protocol	Raw socket communication, byte-level I/O
UDP	ballerina/udp	User Datagram Protocol	Connectionless communication, broadcast/multicast

TCP example

import ballerina/tcp;

// TCP listener
service on new tcp:Listener(9090) {
    remote function onConnect(tcp:Caller caller) returns tcp:ConnectionService {
        return new EchoService();
    }
}

service class EchoService {
    *tcp:ConnectionService;

    remote function onBytes(tcp:Caller caller, readonly & byte[] data) returns byte[]|tcp:Error? {
        return data; // Echo back
    }
}

File transfer protocols

Protocol	Module	Description	Key Features
FTP	ballerina/ftp	File Transfer Protocol	Upload, download, list, directory operations
SFTP	ballerina/ftp	SSH File Transfer Protocol	Encrypted file transfer, key-based authentication

FTP example

import ballerina/ftp;

// FTP client
ftp:Client ftpClient = check new ({
    host: "ftp.example.com",
    port: 21,
    auth: {
        credentials: {username: "user", password: "pass"}
    }
});

// Upload a file
stream<io:Block, io:Error?> fileStream = check io:fileReadBlocksAsStream("data.csv");
check ftpClient->put("/uploads/data.csv", fileStream);

// FTP listener for file events
listener ftp:Listener ftpListener = check new ({
    host: "ftp.example.com",
    auth: {credentials: {username: "user", password: "pass"}},
    path: "/incoming",
    pollingInterval: 30
});

service on ftpListener {
    remote function onFileChange(ftp:WatchEvent & readonly event) {
        foreach ftp:FileInfo file in event.addedFiles {
            io:println("New file: ", file.name);
        }
    }
}

Email protocols

Protocol	Module	Description	Key Features
SMTP	ballerina/email	Simple Mail Transfer Protocol	Send emails with attachments, HTML content
POP3	ballerina/email	Post Office Protocol v3	Receive and download emails
IMAP4	ballerina/email	Internet Message Access Protocol	Read, search, and manage emails on server

Email example

import ballerina/email;

// Send email via SMTP
email:SmtpClient smtp = check new ("smtp.example.com", "[email protected]", "password");

check smtp->sendMessage({
    to: "[email protected]",
    subject: "Order Confirmation",
    body: "Your order has been processed.",
    contentType: "text/plain"
});

// Listen for emails via IMAP
listener email:ImapListener imapListener = check new ({
    host: "imap.example.com",
    username: "[email protected]",
    password: "password",
    pollingInterval: 60
});

service "emailObserver" on imapListener {
    remote function onMessage(email:Message message) {
        io:println("From: ", message.sender);
        io:println("Subject: ", message.'from);
    }
}

Protocol comparison

Protocol	Pattern	Delivery Guarantee	Ordering	Use Case
HTTP	Request/Response	At-most-once	N/A	REST APIs, webhooks
gRPC	Request/Response, Streaming	At-most-once	Per stream	Microservice-to-microservice
GraphQL	Request/Response	At-most-once	N/A	Flexible API queries
WebSocket	Bidirectional streaming	At-most-once	Per connection	Real-time updates
Kafka	Pub/Sub	At-least-once, Exactly-once	Per partition	Event streaming, log aggregation
RabbitMQ	Pub/Sub, Queue	At-least-once	Per queue	Task distribution, async processing
NATS	Pub/Sub, Request/Reply	At-most-once	None	Lightweight cloud messaging
MQTT	Pub/Sub	QoS 0/1/2	Per topic	IoT, edge devices
JMS	Pub/Sub, Queue	At-least-once	Per queue	Enterprise messaging
TCP	Stream	Reliable, ordered	Yes	Custom binary protocols
UDP	Datagram	Unreliable	None	Discovery, broadcast

See also

• Ballerina API Documentation -- Full API docs for all modules
• Connectors Catalog -- Protocol connector guides
• Data Formats -- Supported data formats