Polish apache#3942 : Add Service registry and discovery

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/DefaultPage.java

@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.registry.client;
+
+import java.io.Serializable;
+import java.util.List;
+
+/**
+ * The default implementation of {@link Page}
+ *
+ * @since 2.7.2
+ */
+public class DefaultPage<T> implements Page<T>, Serializable {
+
+    private static final long serialVersionUID = 1099331838954070419L;
+
+    private final int requestOffset;
+
+    private final int requestSize;
+
+    private int totalSize;
+
+    private List<T> data;
+
+    public DefaultPage(int requestOffset, int requestSize) {
+        this.requestOffset = requestOffset;
+        this.requestSize = requestSize;
+    }
+
+    @Override
+    public int getRequestOffset() {
+        return requestOffset;
+    }
+
+    @Override
+    public int getRequestSize() {
+        return requestSize;
+    }
+
+    @Override
+    public int getTotalSize() {
+        return totalSize;
+    }
+
+    public void setTotalSize(int totalSize) {
+        this.totalSize = totalSize;
+    }
+
+    @Override
+    public List<T> getData() {
+        return data;
+    }
+
+    public void setData(List<T> data) {
+        this.data = data;
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/DefaultServiceInstance.java

@@ -0,0 +1,117 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.registry.client;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * The default implementation of {@link ServiceInstance}.
+ *
+ * @since 2.7.2
+ */
+public class DefaultServiceInstance implements ServiceInstance {
+
+    private final String serviceName;
+
+    private final String host;
+
+    private final int port;
+
+    private boolean enabled = true;
+
+    private boolean healthy = true;
+
+    private Map<String, String> metadata = new HashMap<>();
+
+    public DefaultServiceInstance(String serviceName, String host, int port) {
+        this.serviceName = serviceName;
+        this.host = host;
+        this.port = port;
+    }
+
+    @Override
+    public String getServiceName() {
+        return serviceName;
+    }
+
+    @Override
+    public String getHost() {
+        return host;
+    }
+
+    @Override
+    public int getPort() {
+        return port;
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    public void setEnabled(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    @Override
+    public boolean isHealthy() {
+        return healthy;
+    }
+
+    public void setHealthy(boolean healthy) {
+        this.healthy = healthy;
+    }
+
+    @Override
+    public Map<String, String> getMetadata() {
+        return metadata;
+    }
+
+    public void setMetadata(Map<String, String> metadata) {
+        this.metadata = metadata;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof DefaultServiceInstance)) return false;
+        DefaultServiceInstance that = (DefaultServiceInstance) o;
+        return getPort() == that.getPort() &&
+                Objects.equals(getServiceName(), that.getServiceName()) &&
+                Objects.equals(getHost(), that.getHost()) &&
+                Objects.equals(getMetadata(), that.getMetadata());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getServiceName(), getHost(), getPort(), getMetadata());
+    }
+
+    @Override
+    public String toString() {
+        return "DefaultServiceInstance{" +
+                "serviceName='" + serviceName + '\'' +
+                ", host='" + host + '\'' +
+                ", port=" + port +
+                ", enabled=" + enabled +
+                ", healthy=" + healthy +
+                ", metadata=" + metadata +
+                '}';
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/Page.java

@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.registry.client;
+
+import java.util.List;
+
+/**
+ * The model class of pagination
+ *
+ * @since 2.7.2
+ */
+public interface Page<T> {
+
+    /**
+     * Gets the offset of request
+     *
+     * @return positive integer
+     */
+    int getRequestOffset();
+
+    /**
+     * Gets the size of request for query
+     *
+     * @return positive integer
+     */
+    int getRequestSize();
+
+    /**
+     * Returns the total amount of elements.
+     *
+     * @return the total amount of elements
+     */
+    int getTotalSize();
+
+    /**
+     * The data of current page
+     *
+     * @return non-null {@link List}
+     */
+    List<T> getData();
+
+    /**
+     * The size of {@link #getData() data}
+     *
+     * @return positive integer
+     */
+    default int getDataSize() {
+        return getData().size();
+    }
+
+    /**
+     * Returns whether the page has data at all.
+     *
+     * @return
+     */
+    default boolean hasData() {
+        return getDataSize() > 0;
+    }
+}

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/ServiceInstance.java

@@ -21,7 +21,6 @@
 /**
  * The model class of an instance of a service, which is used for service registration and discovery.
  * <p>
- * The inspiration comes from <a href="https://spring.io/projects/spring-cloud-commons">Spring Cloud Commons</a>.
  *
  * @since 2.7.2
  */
@@ -75,4 +74,14 @@ default boolean isHealthy() {
      */
     Map<String, String> getMetadata();
 
+    /**
+     * @return the hash code of current instance.
+     */
+    int hashCode();
+
+    /**
+     * @param another another {@link ServiceInstance}
+     * @return if equals , return <code>true</code>, or <code>false</code>
+     */
+    boolean equals(Object another);
 }

dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/ServiceRegistry.java

@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.registry.client;
+
+/**
+ * The common interface to register and deregister for a service registry
+ *
+ * @since 2.7.2
+ */
+public interface ServiceRegistry {
+
+    /**
+     * Registers an instance of {@link ServiceInstance}.
+     *
+     * @param serviceInstance an instance of {@link ServiceInstance} to be registered
+     * @return If success, return <code>true</code>, or <code>false</code>
+     */
+    boolean register(ServiceInstance serviceInstance);
+
+    /**
+     * Deregisters an instance of {@link ServiceInstance}.
+     *
+     * @param serviceInstance an instance of {@link ServiceInstance} to be deregistered
+     * @return If success, return <code>true</code>, or <code>false</code>
+     */
+    void deregister(ServiceInstance serviceInstance);
+
+    /**
+     * Closes the ServiceRegistry. This is a lifecycle method.
+     */
+    void close();
+}