> ## Documentation Index
> Fetch the complete documentation index at: https://docs.benzinga.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Go Client Library

> The `go-bztcp` package provides a pure-Go implementation of the Benzinga TCP protocol for streaming financial data. 

<Card title="GitHub Repository" icon="github" href="https://github.com/Benzinga/go-bztcp">
  View source code and contribute
</Card>

## Features

* Tested with Go 1.13+
* High performance implementation
* No external dependencies
* Uses Go's context library for cancellation

## Installation

Install the library and example client:

```bash theme={null}
go install github.com/Benzinga/go-bztcp/cmd/bztcp@latest
```

The `bztcp` binary will be installed to `$GOPATH/bin`.

## Quick Start

Test the client using the included binary:

```bash theme={null}
bztcp -v -user YOUR_USERNAME -key YOUR_API_KEY
```

### Command Line Options

| Option  | Description                |
| ------- | -------------------------- |
| `-user` | Your Benzinga TCP username |
| `-key`  | Your API access key        |
| `-v`    | Enable verbose output      |

If successful, you'll see messages similar to:

```
Benzinga TCP Client initializing.
Connecting to 'tcp-v1.benzinga.io:11337' as user 'YOUR_USERNAME' (w/TLS: false)
Connected. Waiting for events.
{"id":49917328,"title":"Alphabet Option Alert..."}
```

## Library Usage

### Core Functions

The library exposes two primary functions:

| Function                      | Description                              |
| ----------------------------- | ---------------------------------------- |
| `bztcp.Dial(addr, user, key)` | Establish connection to the TCP server   |
| `Conn.Stream(ctx, callback)`  | Start streaming messages with a callback |

### Basic Example

```go theme={null}
package main

import (
	"context"
	"fmt"

	"github.com/Benzinga/go-bztcp/bztcp"
)

func main() {
	// Connect to the server
	conn, err := bztcp.Dial("tcp-v1.benzinga.io:11337", "USER", "KEY")
	if err != nil {
		panic(err)
	}

	// Stream messages
	err = conn.Stream(context.Background(), func(stream bztcp.StreamData) {
		fmt.Printf("%#v\n", stream)
	})

	if err != nil {
		panic(err)
	}
}
```

## Advanced Usage

### Context-Based Cancellation

Use Go's context for graceful shutdown:

```go theme={null}
package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"syscall"

	"github.com/Benzinga/go-bztcp/bztcp"
)

func main() {
	conn, err := bztcp.Dial("tcp-v1.benzinga.io:11337", "USER", "KEY")
	if err != nil {
		panic(err)
	}

	// Create cancellable context
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// Handle shutdown signals
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	
	go func() {
		<-sigChan
		fmt.Println("Shutting down...")
		cancel()
	}()

	// Stream with context
	err = conn.Stream(ctx, func(stream bztcp.StreamData) {
		fmt.Printf("Received: %s\n", stream.Title)
	})

	if err != nil && err != context.Canceled {
		fmt.Printf("Error: %v\n", err)
	}
}
```

### Processing Stream Data

The `StreamData` struct contains the parsed message:

```go theme={null}
conn.Stream(ctx, func(stream bztcp.StreamData) {
	// Access message fields
	fmt.Printf("ID: %d\n", stream.ID)
	fmt.Printf("Title: %s\n", stream.Title)
	fmt.Printf("Published: %s\n", stream.Published)
	
	// Process tickers
	for _, ticker := range stream.Tickers {
		fmt.Printf("Ticker: %s\n", ticker.Name)
	}
	
	// Process channels
	for _, channel := range stream.Channels {
		fmt.Printf("Channel: %s\n", channel)
	}
})
```

### Error Handling

```go theme={null}
conn, err := bztcp.Dial("tcp-v1.benzinga.io:11337", "USER", "KEY")
if err != nil {
	log.Fatalf("Failed to connect: %v", err)
}

err = conn.Stream(ctx, handler)
if err != nil {
	switch {
	case err == context.Canceled:
		log.Println("Stream cancelled by user")
	case err == context.DeadlineExceeded:
		log.Println("Stream timeout")
	default:
		log.Printf("Stream error: %v", err)
	}
}
```

## Complete Example

```go theme={null}
package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"

	"github.com/Benzinga/go-bztcp/bztcp"
)

func main() {
	user := os.Getenv("BZTCP_USER")
	key := os.Getenv("BZTCP_KEY")

	if user == "" || key == "" {
		log.Fatal("Set BZTCP_USER and BZTCP_KEY environment variables")
	}

	conn, err := bztcp.Dial("tcp-v1.benzinga.io:11337", user, key)
	if err != nil {
		log.Fatalf("Connection failed: %v", err)
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// Graceful shutdown
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-sigChan
		fmt.Println("\nShutting down gracefully...")
		cancel()
	}()

	fmt.Println("Starting Benzinga TCP stream...")

	err = conn.Stream(ctx, func(stream bztcp.StreamData) {
		// Pretty print the message
		data, _ := json.MarshalIndent(stream, "", "  ")
		fmt.Println(string(data))
	})

	if err != nil && err != context.Canceled {
		log.Printf("Stream ended with error: %v", err)
	}
}
```

## Requirements

* Go 1.13 or later (uses context library, requires Go 1.8+)
* Network access to `tcp-v1.benzinga.io:11337`

## See Also

* [Connection Guide](/tcp-reference/connection) - Server details and authentication
* [Message Format](/tcp-reference/message-format) - JSON structure reference
* [Python Client](/tcp-reference/python-client) - Alternative Python implementation