dubbo學習筆記 七 dubbo-registry

registry 這個模塊主要是 註冊中心

註冊中心+監聽者模式+工廠模式+模板模式  下面是核心的5個方法

RegistryFactory

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed 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 com.alibaba.dubbo.registry;

import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.extension.Adaptive;
import com.alibaba.dubbo.common.extension.SPI;

/**
 * RegistryFactory. (SPI, Singleton, ThreadSafe)
 * 
 * @see com.alibaba.dubbo.registry.support.AbstractRegistryFactory
 * @author william.liangf
 */
@SPI("dubbo")
public interface RegistryFactory {

    /**
     * 連接註冊中心.
     * 
     * 連接註冊中心需處理契約：<br>
     * 1. 當設置check=false時表示不檢查連接，否則在連接不上時拋出異常。<br>
     * 2. 支持URL上的username:password權限認證。<br>
     * 3. 支持backup=10.20.153.10備選註冊中心集羣地址。<br>
     * 4. 支持file=registry.cache本地磁盤文件緩存。<br>
     * 5. 支持timeout=1000請求超時設置。<br>
     * 6. 支持session=60000會話超時或過期設置。<br>
     * 
     * @param url 註冊中心地址，不允許爲空
     * @return 註冊中心引用，總不返回空
     */
    @Adaptive({"protocol"})
    Registry getRegistry(URL url);

}

RegistryService

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed 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 com.alibaba.dubbo.registry;

import java.util.List;

import com.alibaba.dubbo.common.URL;

/**
 * RegistryService. (SPI, Prototype, ThreadSafe)
 * 
 * @see com.alibaba.dubbo.registry.Registry
 * @see com.alibaba.dubbo.registry.RegistryFactory#getRegistry(URL)
 * @author william.liangf
 */
public interface RegistryService {

    /**
     * 註冊數據，比如：提供者地址，消費者地址，路由規則，覆蓋規則，等數據。
     * 
     * 註冊需處理契約：<br>
     * 1. 當URL設置了check=false時，註冊失敗後不報錯，在後臺定時重試，否則拋出異常。<br>
     * 2. 當URL設置了dynamic=false參數，則需持久存儲，否則，當註冊者出現斷電等情況異常退出時，需自動刪除。<br>
     * 3. 當URL設置了category=routers時，表示分類存儲，缺省類別爲providers，可按分類部分通知數據。<br>
     * 4. 當註冊中心重啓，網絡抖動，不能丟失數據，包括斷線自動刪除數據。<br>
     * 5. 允許URI相同但參數不同的URL並存，不能覆蓋。<br>
     * 
     * @param url 註冊信息，不允許爲空，如：dubbo://10.20.153.10/com.alibaba.foo.BarService?version=1.0.0&application=kylin
     */
    void register(URL url);

    /**
     * 取消註冊.
     * 
     * 取消註冊需處理契約：<br>
     * 1. 如果是dynamic=false的持久存儲數據，找不到註冊數據，則拋IllegalStateException，否則忽略。<br>
     * 2. 按全URL匹配取消註冊。<br>
     * 
     * @param url 註冊信息，不允許爲空，如：dubbo://10.20.153.10/com.alibaba.foo.BarService?version=1.0.0&application=kylin
     */
    void unregister(URL url);

    /**
     * 訂閱符合條件的已註冊數據，當有註冊數據變更時自動推送.
     * 
     * 訂閱需處理契約：<br>
     * 1. 當URL設置了check=false時，訂閱失敗後不報錯，在後臺定時重試。<br>
     * 2. 當URL設置了category=routers，只通知指定分類的數據，多個分類用逗號分隔，並允許星號通配，表示訂閱所有分類數據。<br>
     * 3. 允許以interface,group,version,classifier作爲條件查詢，如：interface=com.alibaba.foo.BarService&version=1.0.0<br>
     * 4. 並且查詢條件允許星號通配，訂閱所有接口的所有分組的所有版本，或：interface=*&group=*&version=*&classifier=*<br>
     * 5. 當註冊中心重啓，網絡抖動，需自動恢復訂閱請求。<br>
     * 6. 允許URI相同但參數不同的URL並存，不能覆蓋。<br>
     * 7. 必須阻塞訂閱過程，等第一次通知完後再返回。<br>
     * 
     * @param url 訂閱條件，不允許爲空，如：consumer://10.20.153.10/com.alibaba.foo.BarService?version=1.0.0&application=kylin
     * @param listener 變更事件監聽器，不允許爲空
     */
    void subscribe(URL url, NotifyListener listener);

    /**
     * 取消訂閱.
     * 
     * 取消訂閱需處理契約：<br>
     * 1. 如果沒有訂閱，直接忽略。<br>
     * 2. 按全URL匹配取消訂閱。<br>
     * 
     * @param url 訂閱條件，不允許爲空，如：consumer://10.20.153.10/com.alibaba.foo.BarService?version=1.0.0&application=kylin
     * @param listener 變更事件監聽器，不允許爲空
     */
    void unsubscribe(URL url, NotifyListener listener);

    /**
     * 查詢符合條件的已註冊數據，與訂閱的推模式相對應，這裏爲拉模式，只返回一次結果。
     * 
     * @see com.alibaba.dubbo.registry.NotifyListener#notify(List)
     * @param url 查詢條件，不允許爲空，如：consumer://10.20.153.10/com.alibaba.foo.BarService?version=1.0.0&application=kylin
     * @return 已註冊信息列表，可能爲空，含義同{@link com.alibaba.dubbo.registry.NotifyListener#notify(List<URL>)}的參數。
     */
    List<URL> lookup(URL url);

}

NotifyListener

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed 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 com.alibaba.dubbo.registry;

import java.util.List;

import com.alibaba.dubbo.common.URL;

/**
 * NotifyListener. (API, Prototype, ThreadSafe)
 * 
 * @see com.alibaba.dubbo.registry.RegistryService#subscribe(URL, NotifyListener)
 * @author william.liangf
 */
public interface NotifyListener {

    /**
     * 當收到服務變更通知時觸發。
     * 
     * 通知需處理契約：<br>
     * 1. 總是以服務接口和數據類型爲維度全量通知，即不會通知一個服務的同類型的部分數據，用戶不需要對比上一次通知結果。<br>
     * 2. 訂閱時的第一次通知，必須是一個服務的所有類型數據的全量通知。<br>
     * 3. 中途變更時，允許不同類型的數據分開通知，比如：providers, consumers, routers, overrides，允許只通知其中一種類型，但該類型的數據必須是全量的，不是增量的。<br>
     * 4. 如果一種類型的數據爲空，需通知一個empty協議並帶category參數的標識性URL數據。<br>
     * 5. 通知者(即註冊中心實現)需保證通知的順序，比如：單線程推送，隊列串行化，帶版本對比。<br>
     * 
     * @param urls 已註冊信息列表，總不爲空，含義同{@link com.alibaba.dubbo.registry.RegistryService#lookup(URL)}的返回值。
     */
    void notify(List<URL> urls);

}

FailbackRegistry

    // ==== 模板方法 ====

    protected abstract void doRegister(URL url);

    protected abstract void doUnregister(URL url);

    protected abstract void doSubscribe(URL url, NotifyListener listener);

    protected abstract void doUnsubscribe(URL url, NotifyListener listener);

ZookeeperRegistry

查詢url，走的zk path 

    public List<URL> lookup(URL url) {
        if (url == null) {
            throw new IllegalArgumentException("lookup url == null");
        }
        try {
            List<String> providers = new ArrayList<String>();
            for (String path : toCategoriesPath(url)) {
                    List<String> children = zkClient.getChildren(path);
                    if (children != null) {
                        providers.addAll(children);
                    }
            }
            return toUrlsWithoutEmpty(url, providers);
        } catch (Throwable e) {
            throw new RpcException("Failed to lookup " + url + " from zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
        }
    }