Create sample client

Author: ezynda3

examples/simple_client/main.go

@@ -0,0 +1,193 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"time"
+
+	"github.com/mark3labs/mcp-go/client"
+	"github.com/mark3labs/mcp-go/client/transport"
+	"github.com/mark3labs/mcp-go/mcp"
+)
+
+func main() {
+	// Define command line flags
+	stdioCmd := flag.String("stdio", "", "Command to execute for stdio transport (e.g. 'python server.py')")
+	sseURL := flag.String("sse", "", "URL for SSE transport (e.g. 'http://localhost:8080/sse')")
+	flag.Parse()
+
+	// Validate flags
+	if (*stdioCmd == "" && *sseURL == "") || (*stdioCmd != "" && *sseURL != "") {
+		fmt.Println("Error: You must specify exactly one of --stdio or --sse")
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	// Create a context with timeout
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	// Create client based on transport type
+	var c *client.Client
+	var err error
+
+	if *stdioCmd != "" {
+		fmt.Println("Initializing stdio client...")
+		// Parse command and arguments
+		args := parseCommand(*stdioCmd)
+		if len(args) == 0 {
+			fmt.Println("Error: Invalid stdio command")
+			os.Exit(1)
+		}
+
+		// Create command and stdio transport
+		command := args[0]
+		cmdArgs := args[1:]
+		
+		// Create stdio transport with verbose logging
+		stdioTransport := transport.NewStdio(command, nil, cmdArgs...)
+		
+		// Start the transport
+		if err := stdioTransport.Start(ctx); err != nil {
+			log.Fatalf("Failed to start stdio transport: %v", err)
+		}
+		
+		// Create client with the transport
+		c = client.NewClient(stdioTransport)
+		
+		// Set up logging for stderr if available
+		if stderr, ok := client.GetStderr(c); ok {
+			go func() {
+				buf := make([]byte, 4096)
+				for {
+					n, err := stderr.Read(buf)
+					if err != nil {
+						if err != io.EOF {
+							log.Printf("Error reading stderr: %v", err)
+						}
+						return
+					}
+					if n > 0 {
+						fmt.Fprintf(os.Stderr, "[Server] %s", buf[:n])
+					}
+				}
+			}()
+		}
+	} else {
+		fmt.Println("Initializing SSE client...")
+		// Create SSE transport
+		sseTransport, err := transport.NewSSE(*sseURL)
+		if err != nil {
+			log.Fatalf("Failed to create SSE transport: %v", err)
+		}
+		
+		// Start the transport
+		if err := sseTransport.Start(ctx); err != nil {
+			log.Fatalf("Failed to start SSE transport: %v", err)
+		}
+		
+		// Create client with the transport
+		c = client.NewClient(sseTransport)
+	}
+
+	// Set up notification handler
+	c.OnNotification(func(notification mcp.JSONRPCNotification) {
+		fmt.Printf("Received notification: %s\n", notification.Method)
+	})
+
+	// Initialize the client
+	fmt.Println("Initializing client...")
+	initRequest := mcp.InitializeRequest{}
+	initRequest.Params.ProtocolVersion = mcp.LATEST_PROTOCOL_VERSION
+	initRequest.Params.ClientInfo = mcp.Implementation{
+		Name:    "MCP-Go Simple Client Example",
+		Version: "1.0.0",
+	}
+	initRequest.Params.Capabilities = mcp.ClientCapabilities{}
+	
+	serverInfo, err := c.Initialize(ctx, initRequest)
+	if err != nil {
+		log.Fatalf("Failed to initialize: %v", err)
+	}
+
+	// Display server information
+	fmt.Printf("Connected to server: %s (version %s)\n", 
+		serverInfo.ServerInfo.Name, 
+		serverInfo.ServerInfo.Version)
+	fmt.Printf("Server capabilities: %+v\n", serverInfo.Capabilities)
+
+	// List available tools if the server supports them
+	if serverInfo.Capabilities.Tools != nil {
+		fmt.Println("Fetching available tools...")
+		toolsRequest := mcp.ListToolsRequest{}
+		toolsResult, err := c.ListTools(ctx, toolsRequest)
+		if err != nil {
+			log.Printf("Failed to list tools: %v", err)
+		} else {
+			fmt.Printf("Server has %d tools available\n", len(toolsResult.Tools))
+			for i, tool := range toolsResult.Tools {
+				fmt.Printf("  %d. %s - %s\n", i+1, tool.Name, tool.Description)
+			}
+		}
+	}
+
+	// List available resources if the server supports them
+	if serverInfo.Capabilities.Resources != nil {
+		fmt.Println("Fetching available resources...")
+		resourcesRequest := mcp.ListResourcesRequest{}
+		resourcesResult, err := c.ListResources(ctx, resourcesRequest)
+		if err != nil {
+			log.Printf("Failed to list resources: %v", err)
+		} else {
+			fmt.Printf("Server has %d resources available\n", len(resourcesResult.Resources))
+			for i, resource := range resourcesResult.Resources {
+				fmt.Printf("  %d. %s - %s\n", i+1, resource.URI, resource.Name)
+			}
+		}
+	}
+
+	fmt.Println("Client initialized successfully. Shutting down...")
+	c.Close()
+}
+
+// parseCommand splits a command string into command and arguments
+func parseCommand(cmd string) []string {
+	// This is a simple implementation that doesn't handle quotes or escapes
+	// For a more robust solution, consider using a shell parser library
+	var result []string
+	var current string
+	var inQuote bool
+	var quoteChar rune
+
+	for _, r := range cmd {
+		switch {
+		case r == ' ' && !inQuote:
+			if current != "" {
+				result = append(result, current)
+				current = ""
+			}
+		case (r == '"' || r == '\''):
+			if inQuote && r == quoteChar {
+				inQuote = false
+				quoteChar = 0
+			} else if !inQuote {
+				inQuote = true
+				quoteChar = r
+			} else {
+				current += string(r)
+			}
+		default:
+			current += string(r)
+		}
+	}
+
+	if current != "" {
+		result = append(result, current)
+	}
+
+	return result
+}