Core Binder Framework

/**
 * Strategy interface for binding app interfaces to logical names.
 * @param <T> the binding target type
 * @param <C> the consumer properties type
 * @param <P> the producer properties type
 */
public interface Binder<T, C extends ConsumerProperties, P extends ProducerProperties> {
    /**
     * Bind a consumer to the given name and group.
     * @param name the logical name of the target
     * @param group the consumer group
     * @param inboundBindTarget the consumer binding target
     * @param consumerProperties consumer configuration properties
     * @return the binding handle
     */
    Binding<T> bindConsumer(String name, String group, T inboundBindTarget, C consumerProperties);
    
    /**
     * Bind a producer to the given name.
     * @param name the logical name of the target
     * @param outboundBindTarget the producer binding target
     * @param producerProperties producer configuration properties
     * @return the binding handle
     */
    Binding<T> bindProducer(String name, T outboundBindTarget, P producerProperties);
    
    /**
     * Get the binder identity for management purposes.
     * @return the binder identity, or null if not supported
     */
    default String getBinderIdentity() {
        return null;
    }
}

/**
 * Represents the binding between an input/output and an adapter endpoint.
 * @param <T> the binding target type
 */
public interface Binding<T> extends Pausable {
    /**
     * Get the logical name of this binding.
     * @return the binding name
     */
    String getName();
    
    /**
     * Unbind this binding, cleaning up resources.
     */
    void unbind();
    
    /**
     * Get the current state of this binding.
     * @return the binding state
     */
    State getState();
    
    /**
     * Get the binding name for management purposes.
     * @return the binding name
     */
    String getBindingName();
    
    /**
     * Check if this is an input binding.
     * @return true if input binding, false if output
     */
    boolean isInput();
    
    /**
     * Get the name of the binder that created this binding.
     * @return the binder name
     */
    String getBinderName();
    
    // Lifecycle methods from Pausable
    void pause();
    void resume();
    boolean isPaused();
}

/**
 * Factory for creating binder instances.
 */
public interface BinderFactory {
    /**
     * Get a binder instance for the specified name and type.
     * @param name the binder name, or null for default
     * @param bindingTargetType the binding target type
     * @return the binder instance
     */
    <T> Binder<T, ?, ?> getBinder(String name, Class<T> bindingTargetType);
}

/**
 * Default implementation of BinderFactory.
 */
public class DefaultBinderFactory implements BinderFactory, DisposableBean, ApplicationContextAware {
    public <T> Binder<T, ?, ?> getBinder(String name, Class<T> bindingTargetType);
    public void destroy();
    public void setApplicationContext(ApplicationContext applicationContext);
}

/**
 * Registry of available binder types.
 */
public interface BinderTypeRegistry {
    /**
     * Get a binder type by name.
     * @param name the binder type name
     * @return the binder type, or null if not found
     */
    BinderType get(String name);
    
    /**
     * Get all registered binder types.
     * @return map of binder types keyed by name
     */
    Map<String, BinderType> getAll();
}

/**
 * Default implementation of BinderTypeRegistry.
 */
public class DefaultBinderTypeRegistry implements BinderTypeRegistry {
    public BinderType get(String name);
    public Map<String, BinderType> getAll();
}

/**
 * Binder with extended properties support.
 * @param <T> the binding target type
 * @param <C> the consumer properties type
 * @param <P> the producer properties type
 */
public interface ExtendedPropertiesBinder<T, C extends ConsumerProperties, P extends ProducerProperties> extends Binder<T, C, P> {
    /**
     * Get extended binding properties.
     * @param channelName the channel name
     * @return the extended binding properties, or null if not supported
     */
    ExtendedBindingProperties<C, P> getExtendedPropertiesEntryIfAny(String channelName);
}

/**
 * Binder for pollable consumers.
 * @param <H> the handler type
 * @param <C> the consumer properties type
 */
public interface PollableConsumerBinder<H, C extends ConsumerProperties> extends Binder<PollableSource<H>, C, ProducerProperties> {
    // Inherits binding methods from Binder interface
}

/**
 * Interface for pollable sources.
 * @param <H> the handler type
 */
public interface PollableSource<H> {
    /**
     * Poll for a message.
     * @param handler the message handler
     * @return true if a message was received and handled
     */
    boolean poll(H handler);
}

/**
 * Message-specific pollable source.
 */
public interface PollableMessageSource extends PollableSource<MessageHandler> {
    /**
     * Poll for a message with timeout.
     * @param handler the message handler
     * @param timeout the timeout duration
     * @return true if a message was received within timeout
     */
    default boolean poll(MessageHandler handler, Duration timeout) {
        return poll(handler);
    }
}

/**
 * Default implementation of PollableMessageSource.
 */
public class DefaultPollableMessageSource implements PollableMessageSource, BeanFactoryAware {
    public boolean poll(MessageHandler handler);
    public boolean poll(MessageHandler handler, ParameterizedTypeReference<?> type);
    public void setBeanFactory(BeanFactory beanFactory);
}

/**
 * Base class for binder implementations.
 * @param <T> the binding target type
 * @param <C> the consumer properties type
 * @param <P> the producer properties type
 */
public abstract class AbstractBinder<T, C extends ConsumerProperties, P extends ProducerProperties> implements Binder<T, C, P>, BeanFactoryAware, InitializingBean {
    
    protected abstract Binding<T> doBindConsumer(String name, String group, T inputTarget, C properties);
    protected abstract Binding<T> doBindProducer(String name, T outputTarget, P properties);
    
    public final Binding<T> bindConsumer(String name, String group, T inputTarget, C properties);
    public final Binding<T> bindProducer(String name, T outputTarget, P properties);
    
    public void setBeanFactory(BeanFactory beanFactory);
    public void afterPropertiesSet();
}

/**
 * Base class for message channel binders.
 * @param <C> the consumer properties type
 * @param <P> the producer properties type
 * @param <PP> the provisioning provider type
 */
public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties, P extends ProducerProperties, PP extends ProvisioningProvider<C, P>> extends AbstractBinder<MessageChannel, C, P> implements ExtendedPropertiesBinder<MessageChannel, C, P> {
    
    protected abstract Binding<MessageChannel> doBindConsumer(String name, String group, MessageChannel inputChannel, C properties);
    protected abstract Binding<MessageChannel> doBindProducer(String name, MessageChannel outputChannel, P properties);
    
    public ExtendedBindingProperties<C, P> getExtendedPropertiesEntryIfAny(String channelName);
}

/**
 * Configuration holder for a binder.
 */
public class BinderConfiguration {
    private final Map<String, Object> properties;
    private final boolean inheritEnvironment;
    private final boolean defaultCandidate;
    
    public BinderConfiguration(String type, Map<String, Object> properties, boolean inheritEnvironment, boolean defaultCandidate);
    
    public String getConfigurationName();
    public Map<String, Object> getProperties();
    public boolean isInheritEnvironment();
    public boolean isDefaultCandidate();
}

/**
 * Represents a binder type with configuration classes.
 */
public class BinderType {
    private final String typeName;
    private final Class<?>[] configurationClasses;
    
    public BinderType(String typeName, Class<?>[] configurationClasses);
    
    public String getTypeName();
    public Class<?>[] getConfigurationClasses();
}

/**
 * Default binding implementation.
 * @param <T> the binding target type
 */
public class DefaultBinding<T> implements Binding<T> {
    public DefaultBinding(String name, String group, T target, Lifecycle lifecycle);
    
    public String getName();
    public void unbind();
    public State getState();
    public String getBindingName();
    public boolean isInput();
    public String getBinderName();
    public void pause();
    public void resume();
    public boolean isPaused();
}

/**
 * Handles partitioning logic for messages.
 */
public class PartitionHandler {
    /**
     * Create a partition handler with the given selector strategy.
     * @param partitionSelectorStrategy the partition selector
     * @param partitionCount the number of partitions
     */
    public PartitionHandler(PartitionSelectorStrategy partitionSelectorStrategy, int partitionCount);
    
    /**
     * Determine the partition for a message.
     * @param message the message to partition
     * @return the partition number
     */
    public int determinePartition(Message<?> message);
}

/**
 * Strategy for extracting partition keys from messages.
 */
public interface PartitionKeyExtractorStrategy {
    /**
     * Extract the partition key from a message.
     * @param message the message
     * @return the partition key
     */
    Object extractKey(Message<?> message);
}

/**
 * Strategy for selecting partitions based on keys.
 */
public interface PartitionSelectorStrategy {
    /**
     * Select a partition for the given key.
     * @param key the partition key
     * @param partitionCount the total number of partitions
     * @return the selected partition number
     */
    int selectPartition(Object key, int partitionCount);
}

/**
 * Container for message values and headers.
 */
public class MessageValues implements Map<String, Object>, Serializable {
    public MessageValues(Message<?> original);
    public MessageValues(Object payload, Map<String, Object> headers);
    
    public Object getPayload();
    public void setPayload(Object payload);
    public Map<String, Object> getHeaders();
    public Message<Object> toMessage();
    
    // Map interface methods
    public Object get(Object key);
    public Object put(String key, Object value);
    public Set<String> keySet();
    public Collection<Object> values();
    public Set<Entry<String, Object>> entrySet();
    // ... other Map methods
}

/**
 * Utilities for Java class MIME type handling.
 */
public class JavaClassMimeTypeUtils {
    public static final String JAVA_OBJECT_TYPE = "application/x-java-object";
    public static final String JAVA_SERIALIZED_OBJECT_TYPE = "application/x-java-serialized-object";
    
    /**
     * Convert class name to MIME type.
     * @param className the Java class name
     * @return the corresponding MIME type
     */
    public static MimeType classNameToMimeType(String className);
    
    /**
     * Convert MIME type to class name.
     * @param mimeType the MIME type
     * @return the corresponding Java class name, or null if not applicable
     */
    public static String mimeTypeToClassName(MimeType mimeType);
}

/**
 * Utilities for embedded header handling.
 */
public class EmbeddedHeaderUtils {
    /**
     * Extract headers embedded in message payload.
     * @param message the message with embedded headers
     * @param headerNames the names of headers to extract
     * @return the message with headers extracted to message headers
     */
    public static Message<byte[]> extractHeaders(Message<byte[]> message, String... headerNames);
    
    /**
     * Embed headers into message payload.
     * @param message the message
     * @param headerNames the names of headers to embed
     * @return the message with headers embedded in payload
     */
    public static Message<byte[]> embedHeaders(MessageValues message, String... headerNames);
}

/**
 * Header constants for binder operations.
 */
public class BinderHeaders {
    public static final String STANDARD_HEADERS = "standardHeaders";
    public static final String TARGET_DESTINATION = "scst_targetDestination";
    public static final String PARTITION_HEADER = "scst_partition";
    public static final String PARTITION_OVERRIDE = "scst_partitionOverride";
    public static final String NATIVE_HEADERS_PRESENT = "nativeHeadersPresent";
    public static final String SCST_VERSION = "scst_version";
    public static final String NESTED_EXCEPTIONS_HEADER = "scst_nestedExceptions";
}

/**
 * Header modes for message processing.
 */
public enum HeaderMode {
    /** No headers are processed */
    none,
    /** Headers are processed normally */
    headers,
    /** Headers are embedded in message payload */
    embeddedHeaders
}

/**
 * Event fired when a binding is created.
 */
public class BindingCreatedEvent extends ApplicationEvent {
    /**
     * Create a new binding created event.
     * @param binding the binding that was created
     */
    public BindingCreatedEvent(Binding<?> binding);
    
    /**
     * Get the binding that was created.
     * @return the binding
     */
    public Binding<?> getBinding();
}

/**
 * General binder-related exception.
 */
public class BinderException extends RuntimeException {
    public BinderException(String message);
    public BinderException(String message, Throwable cause);
}

/**
 * Exception to signal message requeuing.
 */
public class RequeueCurrentMessageException extends RuntimeException {
    public RequeueCurrentMessageException(String message);
    public RequeueCurrentMessageException(String message, Throwable cause);
}

import org.springframework.cloud.stream.binder.*;
import org.springframework.integration.channel.DirectChannel;
import org.springframework.messaging.MessageChannel;

// Custom binder implementation
public class MyCustomBinder extends AbstractMessageChannelBinder<ConsumerProperties, ProducerProperties, MyProvisioningProvider> {
    
    @Override
    protected Binding<MessageChannel> doBindConsumer(String name, String group, MessageChannel inputChannel, ConsumerProperties properties) {
        // Implementation for binding consumer
        // Connect inputChannel to external message source
        return new DefaultBinding<>(name, group, inputChannel, lifecycle);
    }
    
    @Override
    protected Binding<MessageChannel> doBindProducer(String name, MessageChannel outputChannel, ProducerProperties properties) {
        // Implementation for binding producer  
        // Connect outputChannel to external message destination
        return new DefaultBinding<>(name, null, outputChannel, lifecycle);
    }
}

// Using BinderFactory
@Component
public class MessageService {
    
    private final BinderFactory binderFactory;
    
    public MessageService(BinderFactory binderFactory) {
        this.binderFactory = binderFactory;
    }
    
    public void createDynamicBinding() {
        Binder<MessageChannel, ?, ?> binder = binderFactory.getBinder("kafka", MessageChannel.class);
        MessageChannel channel = new DirectChannel();
        Binding<MessageChannel> binding = binder.bindProducer("my-topic", channel, new ProducerProperties());
        
        // Use the binding...
        
        // Clean up
        binding.unbind();
    }
}