qwen-code/docs/developers/sdk-java.md

Qwen Code Java SDK

The Qwen Code Java SDK is a minimum experimental SDK for programmatic access to Qwen Code functionality. It provides a Java interface to interact with the Qwen Code CLI, allowing developers to integrate Qwen Code capabilities into their Java applications.

Requirements

• Java >= 1.8
• Maven >= 3.6.0 (for building from source)
• qwen-code >= 0.5.0

Dependencies

• Logging: ch.qos.logback:logback-classic
• Utilities: org.apache.commons:commons-lang3
• JSON Processing: com.alibaba.fastjson2:fastjson2
• Testing: JUnit 5 (org.junit.jupiter:junit-jupiter)

Installation

Add the following dependency to your Maven pom.xml:

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>qwencode-sdk</artifactId>
    <version>{$version}</version>
</dependency>

Or if using Gradle, add to your build.gradle:

implementation 'com.alibaba:qwencode-sdk:{$version}'

Building and Running

Build Commands

# Compile the project
mvn compile

# Run tests
mvn test

# Package the JAR
mvn package

# Install to local repository
mvn install

Quick Start

The simplest way to use the SDK is through the QwenCodeCli.simpleQuery() method:

public static void runSimpleExample() {
    List<String> result = QwenCodeCli.simpleQuery("hello world");
    result.forEach(logger::info);
}

For more advanced usage with custom transport options:

public static void runTransportOptionsExample() {
    TransportOptions options = new TransportOptions()
            .setModel("qwen3-coder-flash")
            .setPermissionMode(PermissionMode.AUTO_EDIT)
            .setCwd("./")
            .setEnv(new HashMap<String, String>() {{put("CUSTOM_VAR", "value");}})
            .setIncludePartialMessages(true)
            .setTurnTimeout(new Timeout(120L, TimeUnit.SECONDS))
            .setMessageTimeout(new Timeout(90L, TimeUnit.SECONDS))
            .setAllowedTools(Arrays.asList("read_file", "write_file", "list_directory"));

    List<String> result = QwenCodeCli.simpleQuery("who are you, what are your capabilities?", options);
    result.forEach(logger::info);
}

For streaming content handling with custom content consumers:

public static void runStreamingExample() {
    QwenCodeCli.simpleQuery("who are you, what are your capabilities?",
            new TransportOptions().setMessageTimeout(new Timeout(10L, TimeUnit.SECONDS)), new AssistantContentSimpleConsumers() {

                @Override
                public void onText(Session session, TextAssistantContent textAssistantContent) {
                    logger.info("Text content received: {}", textAssistantContent.getText());
                }

                @Override
                public void onThinking(Session session, ThinkingAssistantContent thinkingAssistantContent) {
                    logger.info("Thinking content received: {}", thinkingAssistantContent.getThinking());
                }

                @Override
                public void onToolUse(Session session, ToolUseAssistantContent toolUseContent) {
                    logger.info("Tool use content received: {} with arguments: {}",
                            toolUseContent, toolUseContent.getInput());
                }

                @Override
                public void onToolResult(Session session, ToolResultAssistantContent toolResultContent) {
                    logger.info("Tool result content received: {}", toolResultContent.getContent());
                }

                @Override
                public void onOtherContent(Session session, AssistantContent<?> other) {
                    logger.info("Other content received: {}", other);
                }

                @Override
                public void onUsage(Session session, AssistantUsage assistantUsage) {
                    logger.info("Usage information received: Input tokens: {}, Output tokens: {}",
                            assistantUsage.getUsage().getInputTokens(), assistantUsage.getUsage().getOutputTokens());
                }
            }.setDefaultPermissionOperation(Operation.allow));
    logger.info("Streaming example completed.");
}

other examples see src/test/java/com/alibaba/qwen/code/cli/example

Architecture

The SDK follows a layered architecture:

• API Layer: Provides the main entry points through QwenCodeCli class with simple static methods for basic usage
• Session Layer: Manages communication sessions with the Qwen Code CLI through the Session class
• Transport Layer: Handles the communication mechanism between the SDK and CLI process (currently using process transport via ProcessTransport)
• Protocol Layer: Defines data structures for communication based on the CLI protocol
• Utils: Common utilities for concurrent execution, timeout handling, and error management

Key Features

Permission Modes

The SDK supports different permission modes for controlling tool execution:

• default: Write tools are denied unless approved via canUseTool callback or in allowedTools. Read-only tools execute without confirmation.
• plan: Blocks all write tools, instructing AI to present a plan first.
• auto-edit: Auto-approve edit tools (edit, write_file, notebook_edit) while other tools require confirmation.
• yolo: All tools execute automatically without confirmation.

Session Event Consumers and Assistant Content Consumers

The SDK provides two key interfaces for handling events and content from the CLI:

SessionEventConsumers Interface

The SessionEventConsumers interface provides callbacks for different types of messages during a session:

• onSystemMessage: Handles system messages from the CLI (receives Session and SDKSystemMessage)
• onResultMessage: Handles result messages from the CLI (receives Session and SDKResultMessage)
• onAssistantMessage: Handles assistant messages (AI responses) (receives Session and SDKAssistantMessage)
• onPartialAssistantMessage: Handles partial assistant messages during streaming (receives Session and SDKPartialAssistantMessage)
• onUserMessage: Handles user messages (receives Session and SDKUserMessage)
• onOtherMessage: Handles other types of messages (receives Session and String message)
• onControlResponse: Handles control responses (receives Session and CLIControlResponse)
• onControlRequest: Handles control requests (receives Session and CLIControlRequest, returns CLIControlResponse)
• onPermissionRequest: Handles permission requests (receives Session and CLIControlRequest, returns Behavior)

AssistantContentConsumers Interface

The AssistantContentConsumers interface handles different types of content within assistant messages:

• onText: Handles text content (receives Session and TextAssistantContent)
• onThinking: Handles thinking content (receives Session and ThinkingAssistantContent)
• onToolUse: Handles tool use content (receives Session and ToolUseAssistantContent)
• onToolResult: Handles tool result content (receives Session and ToolResultAssistantContent)
• onOtherContent: Handles other content types (receives Session and AssistantContent)
• onUsage: Handles usage information (receives Session and AssistantUsage)
• onPermissionRequest: Handles permission requests (receives Session and CLIControlPermissionRequest, returns Behavior)
• onOtherControlRequest: Handles other control requests (receives Session and ControlRequestPayload, returns ControlResponsePayload)

Relationship Between the Interfaces

Important Note on Event Hierarchy:

• SessionEventConsumers is the high-level event processor that handles different message types (system, assistant, user, etc.)
• AssistantContentConsumers is the low-level content processor that handles different types of content within assistant messages (text, tools, thinking, etc.)

Processor Relationship:

• SessionEventConsumers → AssistantContentConsumers (SessionEventConsumers uses AssistantContentConsumers to process content within assistant messages)

Event Derivation Relationships:

• onAssistantMessage → onText, onThinking, onToolUse, onToolResult, onOtherContent, onUsage
• onPartialAssistantMessage → onText, onThinking, onToolUse, onToolResult, onOtherContent
• onControlRequest → onPermissionRequest, onOtherControlRequest

Event Timeout Relationships:

Each event handler method has a corresponding timeout method that allows customizing the timeout behavior for that specific event:

• onSystemMessage ↔ onSystemMessageTimeout
• onResultMessage ↔ onResultMessageTimeout
• onAssistantMessage ↔ onAssistantMessageTimeout
• onPartialAssistantMessage ↔ onPartialAssistantMessageTimeout
• onUserMessage ↔ onUserMessageTimeout
• onOtherMessage ↔ onOtherMessageTimeout
• onControlResponse ↔ onControlResponseTimeout
• onControlRequest ↔ onControlRequestTimeout

For AssistantContentConsumers timeout methods:

• onText ↔ onTextTimeout
• onThinking ↔ onThinkingTimeout
• onToolUse ↔ onToolUseTimeout
• onToolResult ↔ onToolResultTimeout
• onOtherContent ↔ onOtherContentTimeout
• onPermissionRequest ↔ onPermissionRequestTimeout
• onOtherControlRequest ↔ onOtherControlRequestTimeout

Default Timeout Values:

• SessionEventSimpleConsumers default timeout: 180 seconds (Timeout.TIMEOUT_180_SECONDS)
• AssistantContentSimpleConsumers default timeout: 60 seconds (Timeout.TIMEOUT_60_SECONDS)

Timeout Hierarchy Requirements:

For proper operation, the following timeout relationships should be maintained:

• onAssistantMessageTimeout return value should be greater than onTextTimeout, onThinkingTimeout, onToolUseTimeout, onToolResultTimeout, and onOtherContentTimeout return values
• onControlRequestTimeout return value should be greater than onPermissionRequestTimeout and onOtherControlRequestTimeout return values

Transport Options

The TransportOptions class allows configuration of how the SDK communicates with the Qwen Code CLI:

• pathToQwenExecutable: Path to the Qwen Code CLI executable
• cwd: Working directory for the CLI process
• model: AI model to use for the session
• permissionMode: Permission mode that controls tool execution
• env: Environment variables to pass to the CLI process
• maxSessionTurns: Limits the number of conversation turns in a session
• coreTools: List of core tools that should be available to the AI
• excludeTools: List of tools to exclude from being available to the AI
• allowedTools: List of tools that are pre-approved for use without additional confirmation
• authType: Authentication type to use for the session
• includePartialMessages: Enables receiving partial messages during streaming responses
• turnTimeout: Timeout for a complete turn of conversation
• messageTimeout: Timeout for individual messages within a turn
• resumeSessionId: ID of a previous session to resume
• otherOptions: Additional command-line options to pass to the CLI

Session Control Features

• Session creation: Use QwenCodeCli.newSession() to create a new session with custom options
• Session management: The Session class provides methods to send prompts, handle responses, and manage session state
• Session cleanup: Always close sessions using session.close() to properly terminate the CLI process
• Session resumption: Use setResumeSessionId() in TransportOptions to resume a previous session
• Session interruption: Use session.interrupt() to interrupt a currently running prompt
• Dynamic model switching: Use session.setModel() to change the model during a session
• Dynamic permission mode switching: Use session.setPermissionMode() to change the permission mode during a session

Thread Pool Configuration

The SDK uses a thread pool for managing concurrent operations with the following default configuration:

• Core Pool Size: 30 threads
• Maximum Pool Size: 100 threads
• Keep-Alive Time: 60 seconds
• Queue Capacity: 300 tasks (using LinkedBlockingQueue)
• Thread Naming: "qwen_code_cli-pool-{number}"
• Daemon Threads: false
• Rejected Execution Handler: CallerRunsPolicy

Error Handling

The SDK provides specific exception types for different error scenarios:

• SessionControlException: Thrown when there's an issue with session control (creation, initialization, etc.)
• SessionSendPromptException: Thrown when there's an issue sending a prompt or receiving a response
• SessionClosedException: Thrown when attempting to use a closed session

FAQ / Troubleshooting

Q: Do I need to install the Qwen CLI separately?

A: yes, requires Qwen CLI 0.5.5 or higher.

Q: What Java versions are supported?

A: The SDK requires Java 1.8 or higher.

Q: How do I handle long-running requests?

A: The SDK includes timeout utilities. You can configure timeouts using the Timeout class in TransportOptions.

Q: Why are some tools not executing?

A: This is likely due to permission modes. Check your permission mode settings and consider using allowedTools to pre-approve certain tools.

Q: How do I resume a previous session?

A: Use the setResumeSessionId() method in TransportOptions to resume a previous session.

Q: Can I customize the environment for the CLI process?

A: Yes, use the setEnv() method in TransportOptions to pass environment variables to the CLI process.

License

Apache-2.0 - see LICENSE for details.