Talk about the MessagingAccessPoint of openmessaging.

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This article mainly studies the MessagingAccessPoint of openmessaging.

MessagingAccessPoint

openmessaging-java/openmessaging-api/src/main/java/io/openmessaging/MessagingAccessPoint.java

/**
 * An instance of {@code MessagingAccessPoint} may be obtained from {@link OMS}, which is capable of creating {@code
 * Producer}, {@code Consumer}, {@code ResourceManager}, and other facility entities.
 * <p>
 * For example:
 * <pre>
 * MessagingAccessPoint messagingAccessPoint = OMS.getMessagingAccessPoint("oms:rocketmq://alice@rocketmq.apache.org/us-east:default_space");
 * messagingAccessPoint.startup();
 * Producer producer = messagingAccessPoint.createProducer();
 * producer.startup();
 * producer.send(producer.createBytesMessage("HELLO_QUEUE", "HELLO_BODY".getBytes(Charset.forName("UTF-8"))));
 * </pre>
 *
 * @version OMS 1.0.0
 * @since OMS 1.0.0
 */
public interface MessagingAccessPoint extends ServiceLifecycle {

    /**
     * Returns the target OMS specification version of the specified vendor implementation.
     *
     * @return the OMS version of implementation
     * @see OMS#specVersion
     */
    String implVersion();

    /**
     * Returns the attributes of this {@code MessagingAccessPoint} instance.
     * <p>
     * There are some standard attributes defined by OMS for {@code MessagingAccessPoint}:
     * <ul>
     * <li> {@link OMSBuiltinKeys#ACCESS_POINTS}, the specified access points.
     * <li> {@link OMSBuiltinKeys#DRIVER_IMPL}, the fully qualified class name of the specified MessagingAccessPoint's
     * implementation, the default value is {@literal io.openmessaging.<driver_type>.MessagingAccessPointImpl}.
     * <li> {@link OMSBuiltinKeys#REGION}, the region the resources reside in.
     * <li> {@link OMSBuiltinKeys#ACCOUNT_ID}, the ID of the specific account system that owns the resource.
     * </ul>
     *
     * @return the attributes
     */
    KeyValue attributes();

    /**
     * Creates a new {@code Producer} for the specified {@code MessagingAccessPoint}.
     *
     * @return the created {@code Producer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    Producer createProducer();

    /**
     * Creates a new {@code Producer} for the specified {@code MessagingAccessPoint}
     * with some preset attributes.
     *
     * @param attributes the preset attributes
     * @return the created {@code Producer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    Producer createProducer(KeyValue attributes);

    /**
     * Creates a new {@code PushConsumer} for the specified {@code MessagingAccessPoint}.
     * The returned {@code PushConsumer} isn't attached to any queue,
     * uses {@link PushConsumer#attachQueue(String, MessageListener)} to attach queues.
     *
     * @return the created {@code PushConsumer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    PushConsumer createPushConsumer();

    /**
     * Creates a new {@code PushConsumer} for the specified {@code MessagingAccessPoint} with some preset attributes.
     *
     * @param attributes the preset attributes
     * @return the created {@code PushConsumer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    PushConsumer createPushConsumer(KeyValue attributes);

    /**
     * Creates a new {@code PullConsumer} for the specified {@code MessagingAccessPoint}.
     *
     * @return the created {@code PullConsumer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    PullConsumer createPullConsumer();

    /**
     * Creates a new {@code PullConsumer} for the specified {@code MessagingAccessPoint} with some preset attributes.
     *
     * @param attributes the preset attributes
     * @return the created {@code PullConsumer}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    PullConsumer createPullConsumer(KeyValue attributes);

    /**
     * Creates a new {@code StreamingConsumer} for the specified {@code MessagingAccessPoint}.
     *
     * @return the created {@code Stream}
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    StreamingConsumer createStreamingConsumer();

    /**
     * Creates a new {@code StreamingConsumer} for the specified {@code MessagingAccessPoint} with some preset
     * attributes.
     *
     * @param attributes the preset attributes
     * @return the created consumer
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    StreamingConsumer createStreamingConsumer(KeyValue attributes);

    /**
     * Gets a lightweight {@code ResourceManager} instance from the specified {@code MessagingAccessPoint}.
     *
     * @return the resource manger
     * @throws OMSRuntimeException if the {@code MessagingAccessPoint} fails to handle this request
     * due to some internal error
     */
    ResourceManager resourceManager();
}
  • MessagingAccessPoint is similar to OMS’s factory method. It aggregates methods for creating various objects, such as createProducer, createPushConsumer, createPullConsumer, and resourceManager.

OMS

openmessaging-java/openmessaging-api/src/main/java/io/openmessaging/OMS.java

/**
 * The oms class provides some static methods to create a {@code MessagingAccessPoint}
 * from the specified OMS driver url and some useful util methods.
 * <p>
 * The complete OMS driver URL syntax is:
 * <p>
 * {@literal oms:<driver_type>://[account_id@]host1[:port1][,host2[:port2],...[,hostN[:portN]]]/<region>}
 * <p>
 * The first part of the URL specifies which OMS implementation is to be used, rocketmq is a
 * optional driver type.
 * <p>
 * The brackets indicate that the extra access points are optional, and a correct OMS driver url
 * needs at least one access point, which consists of hostname and port, like localhost:8081.
 *
 * @version OMS 1.0.0
 * @see ResourceManager
 * @since OMS 1.0.0
 */
public final class OMS {
    /**
     * Returns a {@code MessagingAccessPoint} instance from the specified OMS driver url.
     *
     * @param url the specified OMS driver url
     * @return a {@code MessagingAccessPoint} instance
     * @throws OMSRuntimeException if the factory fails to create a {@code MessagingAccessPoint} due to some driver url
     * some syntax error or internal error.
     */
    public static MessagingAccessPoint getMessagingAccessPoint(String url) {
        return getMessagingAccessPoint(url, OMS.newKeyValue());
    }

    /**
     * Returns a {@code MessagingAccessPoint} instance from the specified OMS driver url
     * with some preset attributes, which will be passed to MessagingAccessPoint's implementation
     * class as a unique constructor parameter.
     *
     * There are some standard attributes defined by OMS for this method,
     * the same as {@link MessagingAccessPoint#attributes()}
     *
     * @param url the specified OMS driver url
     * @return a {@code MessagingAccessPoint} instance
     * @throws OMSRuntimeException if the factory fails to create a {@code MessagingAccessPoint} due to some driver url
     * some syntax error or internal error.
     */
    public static MessagingAccessPoint getMessagingAccessPoint(String url, KeyValue attributes) {
        return MessagingAccessPointAdapter.getMessagingAccessPoint(url, attributes);
    }

    /**
     * Returns a default and internal {@code KeyValue} implementation instance.
     *
     * @return a {@code KeyValue} instance
     */
    public static KeyValue newKeyValue() {
        return new DefaultKeyValue();
    }

    /**
     * The version format is X.Y.Z (Major.Minor.Patch), a pre-release version may be denoted by appending a hyphen and a
     * series of dot-separated identifiers immediately following the patch version, like X.Y.Z-alpha.
     *
     * <p>
     * OMS version follows semver scheme partially.
     *
     * @see <a href="http://semver.org">http://semver.org</a>
     */
    public static String specVersion = "UnKnown";

    static {
        InputStream stream = OMS.class.getClassLoader().getResourceAsStream("oms.spec.properties");
        try {
            if (stream != null) {
                Properties properties = new Properties();
                properties.load(stream);
                specVersion = String.valueOf(properties.get("version"));
            }
        } catch (IOException ignore) {
        }
    }

    private OMS() {
    }
}
  • OMS can be understood as a total entry and is a static factory method for MessagingAccessPoint.
  • It parses access address and other information according to url, such as OMS: Rocketmq://Alice @ Rocketmq.Apache.org/us-east: default _ space

ResourceManager

openmessaging-java/openmessaging-api/src/main/java/io/openmessaging/ResourceManager.java

/**
 * The {@code ResourceManager} is to provide a unified interface of resource management,
 * allowing developers to manage the namespace, queue and routing resources.
 * <p>
 * Create, set, get and delete are the four basic operations of {@code ResourceManager}.
 * <p>
 * {@code ResourceManager} also supports dynamic fetch and update of resource attributes.
 * <p>
 * {@link MessagingAccessPoint#resourceManager()} ()} is the unique method to obtain a {@code ResourceManager}
 * instance. Changes made through this instance will immediately apply to the message-oriented middleware (MOM) behind
 * {@code MessagingAccessPoint}.
 *
 * @version OMS 1.0.0
 * @since OMS 1.0.0
 */
public interface ResourceManager {
    /**
     * Creates a {@code Namespace} resource with some preset attributes.
     * <p>
     * A namespace wraps the OMS resources in an abstract concept that makes it appear to the users
     * within the namespace that they have their own isolated instance of the global OMS resources.
     *
     * @param nsName the name of the new namespace
     * @param attributes the preset attributes
     */
    void createNamespace(String nsName, KeyValue attributes);

    /**
     * Sets the attributes of the specific namespace, the old attributes will be replaced
     * by the provided attributes, only the provided key will be updated.
     *
     * @param nsName the specific namespace
     * @param attributes the new attributes
     * @throws OMSResourceNotExistException if the specific namespace does not exist
     */
    void setNamespaceAttributes(String nsName, KeyValue attributes) throws OMSResourceNotExistException;

    /**
     * Gets the attributes of the specific namespace.
     *
     * @param nsName the specific namespace
     * @return the attributes of namespace
     * @throws OMSResourceNotExistException if the specific namespace does not exist
     */
    KeyValue getNamespaceAttributes(String nsName) throws OMSResourceNotExistException;

    /**
     * Deletes an existing namespace resource.
     *
     * @param nsName the namespace needs to be deleted
     * @throws OMSResourceNotExistException if the specified namespace does not exist
     */
    void deleteNamespace(String nsName) throws OMSResourceNotExistException;

    /**
     * Gets the namespace list in the current {@code MessagingAccessPoint}.
     *
     * @return the list of all namespaces
     */
    List<String> listNamespaces();

    /**
     * Creates a {@code Queue} resource in the configured namespace with some preset attributes.
     * <p>
     * The standard OMS {@code Queue} schema must start with the {@code Namespace} prefix:
     * <p>
     * {@literal <namespace_name>://<queue_name>}
     *
     * @param queueName the name of the new queue
     * @param attributes the preset attributes
     * @throws OMSResourceNotExistException if the configured namespace does not exist or specified queue name is
     * not available
     */
    void createQueue(String queueName, KeyValue attributes) throws OMSResourceNotExistException;

    /**
     * Sets the attributes of the specified queue, the old attributes will be replaced
     * by the provided attributes, only the provided key will be updated.
     *
     * @param queueName the queue name
     * @param attributes the new attributes
     * @throws OMSResourceNotExistException if the specified queue or namespace does not exist
     */
    void setQueueAttributes(String queueName, KeyValue attributes) throws OMSResourceNotExistException;

    /**
     * Gets the attributes of the specified queue.
     *
     * @param queueName the queue name
     * @return the attributes of namespace
     * @throws OMSResourceNotExistException if the specified queue or namespace does not exist
     */
    KeyValue getQueueAttributes(String queueName) throws OMSResourceNotExistException;

    /**
     * Deletes an existing queue resource.
     *
     * @param queueName the queue needs to be deleted
     * @throws OMSResourceNotExistException if the specified queue or namespace does not exist
     */
    void deleteQueue(String queueName) throws OMSResourceNotExistException;

    /**
     * Gets the queue list in the specific namespace.
     *
     * @param nsName the specific namespace
     * @return the list of all queues
     * @throws OMSResourceNotExistException if the specific namespace does not exist
     */
    List<String> listQueues(String nsName) throws OMSResourceNotExistException;

    /**
     * Creates a {@code Routing} resource in the configured namespace with some preset attributes.
     * <p>
     * The standard OMS {@code Routing} schema must start with the {@code Namespace} prefix:
     * <p>
     * {@literal <namespace_name>://<routing_name>}
     *
     * @param routingName the name of the new routing
     * @param attributes the preset attributes
     * @throws OMSResourceNotExistException if the configured namespace does not exist or specified routing name is not
     * available
     */
    void createRouting(String routingName, KeyValue attributes) throws OMSResourceNotExistException;

    /**
     * Sets the attributes of the specified routing, the old attributes will be replaced
     * by the provided attributes, only the provided key will be updated.
     *
     * @param routingName the routing name
     * @param attributes the new attributes
     * @throws OMSResourceNotExistException if the specified routing or namespace does not exist
     */
    void setRoutingAttributes(String routingName, KeyValue attributes) throws OMSResourceNotExistException;

    /**
     * Gets the attributes of the specified routing.
     *
     * @param routingName the routing name
     * @return the attributes of routing
     * @throws OMSResourceNotExistException if the specified routing or namespace does not exist
     */
    KeyValue getRoutingAttributes(String routingName) throws OMSResourceNotExistException;

    /**
     * Deletes an existing routing resource.
     *
     * @param routingName the routing needs to be deleted
     * @throws OMSResourceNotExistException if the specified routing or namespace does not exist
     */
    void deleteRouting(String routingName) throws OMSResourceNotExistException;

    /**
     * Gets the routing list in the specific namespace.
     *
     * @param nsName the specific namespace
     * @return the list of all routings
     * @throws OMSResourceNotExistException if the specific namespace does not exist
     */
    List<String> listRoutings(String nsName) throws OMSResourceNotExistException;

    /**
     * Gets the stream list behind the specified queue.
     *
     * @param queueName the queue name
     * @return the list of all streams
     * @throws OMSResourceNotExistException if the specified queue or namespace does not exist
     */
    List<String> listStreams(String queueName) throws OMSResourceNotExistException;

    /**
     * Updates some system headers of a message in the configured namespace.
     * <p>
     * Below system headers are allowed to be changed dynamically:
     * <ul>
     * <li>{@link Message.BuiltinKeys#START_TIME}</li>
     * <li>{@link Message.BuiltinKeys#STOP_TIME}</li>
     * <li>{@link Message.BuiltinKeys#TIMEOUT}</li>
     * <li>{@link Message.BuiltinKeys#PRIORITY}</li>
     * <li>{@link Message.BuiltinKeys#SCHEDULE_EXPRESSION}</li>
     * </ul>
     *
     * @param queueName the specific queue the message resides in
     * @param messageId the id of message
     * @param headers the new headers
     * @throws OMSResourceNotExistException if the specified queue, namespace or message does not exist
     */
    void updateMessage(String queueName, String messageId, KeyValue headers) throws OMSResourceNotExistException;
}
  • The operation methods of namespace, queue, routing, etc. are provided.
  • Namespace-related operations include createNamespace, setNamespaceAttributes, deleteNamespace, listNamespaces, and GETTNAMESPACE ATTRIBUTES
  • Queue-related operations include createQueue, setQueueAttributes, getQueueAttributes, deleteQueue, listQueues
  • Routing-related operations include createRouting, setRoutingAttributes, GETTROUTING GATTRIBUTES, deleteRouting, listRoutings
  • The listStreams and updateMessage methods are also provided through.

Summary

The MessagingAccessPoint of openmessaging aggregates the relevant access operators, which can be understood as a facade. In addition, OMS is the static factory of MessagingAccessPoint, while ResourceManager is similar to kafkaAdmin and is used for operation management of namespace, queue, routing, etc.

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