init dubbo 2.7

internal-dubbo/CHANGES.md

+# Release Notes
+
+## 2.7.1
+
+### Notice
+
+'zkclient' extension for 'org.apache.dubbo.remoting.zookeeper.ZookeeperTransporter' is removed from Dubbo 2.7.1, and 'curator' extension becomes the default extension. If you happen to config your application to use 'zkclient' explicitly, pls. switch to use 'curator' instead.
+
+### New Features
+
+- service register support on nacos [#3582](https://github.com/apache/incubator-dubbo/issues/3582)
+- support consul as registry center, config center and metadata center [#983](https://github.com/apache/incubator-dubbo/issues/983)
+- service registry support/config center support on etcd [#808](https://github.com/apache/incubator-dubbo/issues/808)
+- metrics support in dubbo 2.7.1 [#3598](https://github.com/apache/incubator-dubbo/issues/3598)
+- @Argument @Method support [#2405](https://github.com/apache/incubator-dubbo/issues/2045)
+
+### Enhancement
+
+- [Enhancement] @EnableDubboConfigBinding annotates @Repeatable [#1770](https://github.com/apache/incubator-dubbo/issues/1770)
+- [Enhancement] Change the default behavior of @EnableDubboConfig.multiple() [#3193](https://github.com/apache/incubator-dubbo/issues/3193)
+- Should make annotation easier to use in multiple items circumstance [#3039](https://github.com/apache/incubator-dubbo/issues/3039)
+- NoSuchMethodError are thrown when add custom Filter using dubbo2.6.5 and JDK1.6 and upgrade to dubbo2.7.0 [#3570](https://github.com/apache/incubator-dubbo/issues/3570)
+- introduce dubbo-dependencies-zookeeper [#3607](https://github.com/apache/incubator-dubbo/pull/3607)
+- Zookeeper ConfigCenter reuse the client abstraction and connection session [#3288](https://github.com/apache/incubator-dubbo/issues/3288)
+- [Survey] Is it necessary to continue to maintain zkclient in dubbo project? [#3569](https://github.com/apache/incubator-dubbo/issues/3569)
+- Start to use IdleStateHandler in Netty4 [#3341](https://github.com/apache/incubator-dubbo/pull/3341)
+- Support multiple shared links [#2457](https://github.com/apache/incubator-dubbo/pull/2457)
+- Optimize heartbeat [#3299](https://github.com/apache/incubator-dubbo/pull/3299)
+- AccessLogFilter simple date format reduce instance creation [#3026](https://github.com/apache/incubator-dubbo/issues/3026)
+- Support wildcard ip for tag router rule. [#3289](https://github.com/apache/incubator-dubbo/issues/3289)
+- ScriptRouter should cache CompiledScript [#390](https://github.com/apache/incubator-dubbo/issues/390)
+- Optimize compareTo in Router to guarantee consistent behaviour. [#3302](https://github.com/apache/incubator-dubbo/issues/3302)
+- RMI protocol doesn't support generic invocation [#2779](https://github.com/apache/incubator-dubbo/issues/2779)
+- a more elegant way to enhance HashedWheelTimer [#3567](https://github.com/apache/incubator-dubbo/pull/3567)
+- obtain local address incorrectly sometimes in dubbo [#538](https://github.com/apache/incubator-dubbo/issues/538)
+- implement pull request #3412 on master branch [#3418](https://github.com/apache/incubator-dubbo/pull/3418)
+- enhancement for event of response (follow up for pull request #3043) [#3244](https://github.com/apache/incubator-dubbo/issues/3244)
+- bump up hessian-lite version #3423 [#3513](https://github.com/apache/incubator-dubbo/pull/3513)
+- [Dubbo-3610]make snakeyaml transitive, should we do this? [#3659](https://github.com/apache/incubator-dubbo/pull/3659)
+
+### Bugfixes
+
+- cannot register REST service in 2.7 due to the changes in RestProtoco#getContextPath [#3445](https://github.com/apache/incubator-dubbo/issues/3445)
+- Conflict between curator client and dubbo [#3574](https://github.com/apache/incubator-dubbo/issues/3574)
+- is there a problem in NettyBackedChannelBuffer.setBytes(...)? [#2619](https://github.com/apache/incubator-dubbo/issues/2619)
+- [Dubbo - client always reconnect offline provider] Dubbo client bug [#3158](https://github.com/apache/incubator-dubbo/issues/3158)
+- fix heartbeat internal [#3579](https://github.com/apache/incubator-dubbo/pull/3579)
+- logic issue in RedisRegistry leads to services cannot be discovered. [#3291](https://github.com/apache/incubator-dubbo/pull/3291)
+- Multicast demo fails with message "Can't assign requested address" [#2423](https://github.com/apache/incubator-dubbo/issues/2423)
+- Fix thrift protocol, use path to locate exporter. [#3331](https://github.com/apache/incubator-dubbo/pull/3331)
+- cannot use override to modify provider's configuration when hessian protocol is used [#900](https://github.com/apache/incubator-dubbo/issues/900)
+- Condition is not properly used ? [#1917](https://github.com/apache/incubator-dubbo/issues/1917)
+- connectionMonitor in RestProtocol seems not work [#3237](https://github.com/apache/incubator-dubbo/issues/3237)
+- fail to parse config text with white space [#3367](https://github.com/apache/incubator-dubbo/issues/3367)
+- @Reference check=false doesn't take effect [#195](https://github.com/apache/incubator-dubbo/issues/195)
+- [Issue] SpringStatusChecker execute errors on non-XML Spring configuration [#3615](https://github.com/apache/incubator-dubbo/issues/3615)
+- monitor's cluster config is set to failsafe and set to failsafe only [#274](https://github.com/apache/incubator-dubbo/issues/274)
+- A question for ReferenceConfigCache. [#1293](https://github.com/apache/incubator-dubbo/issues/1293)
+- referenceconfig#destroy never invoke unregister [#3294](https://github.com/apache/incubator-dubbo/issues/3294)
+- Fix when qos is disable,log will print every time [#3397](https://github.com/apache/incubator-dubbo/pull/3397)
+- service group is not supported in generic direct invocation [#3555](https://github.com/apache/incubator-dubbo/issues/3555)
+- setOnreturn doesn't take effect in async generic invocation [#208](https://github.com/apache/incubator-dubbo/issues/208)
+- Fix timeout filter not work in async way [#3174](https://github.com/apache/incubator-dubbo/pull/3174)
+- java.lang.NumberFormatException: For input string: "" [#3069](https://github.com/apache/incubator-dubbo/issues/3069)
+- NPE occurred when the configuration was deleted [#3533](https://github.com/apache/incubator-dubbo/issues/3533)
+- NPE when package of interface is empty [#3556](https://github.com/apache/incubator-dubbo/issues/3556)
+- NPE when exporting rest service using a given path. [#3477](https://github.com/apache/incubator-dubbo/issues/3477)
+- NullPointerException happened when using SpringContainer.getContext() [#3476](https://github.com/apache/incubator-dubbo/issues/3476)
+- Why does not tomcat throw an exception when `server.start` failed with a socket binding error.  [#3236](https://github.com/apache/incubator-dubbo/issues/3236)
+- No such extension org.apache.dubbo.metadata.store.MetadataReportFactory by name redis [#3514](https://github.com/apache/incubator-dubbo/issues/3514)
+- dubbo 2.7.1-SNAPSHOT NoClassDefFoundError when use springboot [#3426](https://github.com/apache/incubator-dubbo/issues/3426)
+- NPE occurs when use @Reference in junit in spring boot application [#3429](https://github.com/apache/incubator-dubbo/issues/3429)
+- When refer the same service with more than one @References(with different configs) on consumer side, only one take effect [#1306](https://github.com/apache/incubator-dubbo/issues/1306)
+- consumer always catch java.lang.reflect.UndeclaredThrowableException for the exception thrown from provider [#3386](https://github.com/apache/incubator-dubbo/issues/3386)
+- dubbo2.7.0 com.alibaba.com.caucho.hessian.io.HessianProtocolException: 'com.alibaba.dubbo.common.URL' could not be instantiated [#3342](https://github.com/apache/incubator-dubbo/issues/3342)
+- Close Resources Properly [#3473](https://github.com/apache/incubator-dubbo/issues/3473)
+- SPI entires dup by 3 times. [#2842](https://github.com/apache/incubator-dubbo/issues/2842)
+- provider gets wrong interface name from attachment when use generic invocation in 2.6.3 [#2981](https://github.com/apache/incubator-dubbo/issues/2981)
+- HashedWheelTimer's queue gets full [#3449](https://github.com/apache/incubator-dubbo/issues/3449)
+- Modify MetadataReportRetry ThreadName [#3550](https://github.com/apache/incubator-dubbo/pull/3550)
+- Keep interface key in the URL in simplify mode when it's different from path. [#3478](https://github.com/apache/incubator-dubbo/issues/3478)
+- nc is not stable in dubbo's bootstrap script [#936](https://github.com/apache/incubator-dubbo/issues/936)
+
+## 2.7.0
+
+Requirements: **Java 8+** required
+
+Please check [here](https://github.com/apache/incubator-dubbo/blob/2.7.0-release/CHANGES.md#upgrading-and-compatibility-notifications) for notes and possible compatibility issues for upgrading from 2.6.x or lower to 2.7.0.
+
+### New Features
+
+- Enhancement of service governance rules.
+  - Enriched Routing Rules.
+    1. Conditional Routing. Supports both application-level and service-level conditions.
+    2. Tag Routing. Newly introduced to better support traffic isolation, such as grey deployment.
+  - Decoupling governance rules with the registry, making it easier to extend. Apollo and Zookeeper are available in this version. Nacos support is on the way...
+  - Application-level Dynamic Configuration support.
+  - Use YAML as the configuration language, which is more friendly to read and use.
+
+- Externalized Configuration. Supports reading `dubbo.properties` hosted in remote centralized configuration center - centralized configuration.
+
+- Simplified registry URL. With lower Registry memory use and less notification pressure from Service Directory, separates Configuration notification from Service Discovery.
+
+- Metadata Center. A totally new concept since 2.7.0,  used to store service metadata including static configuration, service definition, method signature, etc.. By default, Zookeeper and Redis are supported as the backend storage. Will work as the basis of service testing, mock and other service governance features going to be supported in [Dubbo-Admin](https://github.com/apache/incubator-dubbo-admin).
+
+- Asynchronous Programming Model (only works for Dubbo protocol now)
+  - Built-in support for the method with CompletableFuture<T> signature.
+  - Server-side asynchronous support, with an AsyncContext API works like Servlet 3.0.
+  - Asynchronous filter chain callback.
+
+- Serialization Extension: Protobuf.
+
+- Caching Policy Extension: Expiring Cache.
+
+### Enhancements / Bugfixes
+
+- Load Balancing strategy enhancement: ConsitentHash #2190, LeastActive #2171, Random #2597, RoundRobin #2650.
+
+- Third-party dependency upgrading.
+  - Switch default remoting to Netty 4.
+  - Switch default Zookeeper client to Curator.
+  - Upgrade Jetty to 9.x.
+
+- IPV6 support #2079.
+
+- Performance tuning, check hanging requests on a closed channel, make them return directly #2185.
+
+- Fixed the serialization problem of JDK primitive types in Kryo #2178.
+
+- Fixed the problem of failing to notify Consumer as early as possible after the Provider side deserialization failed #1903.
+
+### Upgrading and Compatibility Notifications
+
+We have always keep compatibility in mind during the whole process of 2.7.0. We even want old users to upgrade with only on pom version upgrade, but it's hard to achieve that, especially when considering that we have the package renamed in this version, so we had some tradeoffs. If you only used the Dubbo's most basic features, you may have little problems of upgrading, but if you have used some advanced features or have some SPI extensions inside, you'd better read the upgrade notifications carefully. The compatibility issues can be classified into the following 5 categories, for each part, there will have detailed dos and don'ts published later in the official website.
+
+1. Interoperability between 2.7.0 and lower versions
+
+2. Package renaming
+
+   com.alibaba.dubbo -> org.apache.dubbo
+
+3. Simplification of registered URLs
+
+4. Service Governance Rules
+
+5. Configuration
+
+## 2.6.6
+
+Enhancement / New feature：
+
+* tag route.  #3065 
+* Use Netty4 as default Netty version. #3029 
+* upporting Java 8 Date/Time type when serializing with Kryo #3519 
+* supoort config telnet  #3511
+* add annotation driven in MethodConfig and ArgumentConfig #2603
+* add nacos-registry module #3296  
+* add `protocol` attribute in `@Rerefence` #3555 
+*support the hierarchical interface in @Service  #3251  
+* change the default behavior in `@EnableDubboConfig.multiple()` #3193 
+* inline source code of `spring-context-support` #3192 
+* Simplify externalized configuration of Dubbo Protocol name  #3189 
+
+BugFix：
+ 
+* update hessian-lite to 2.3.5, fix unnecessary class load #3538 
+* Fix unregister when client destroyed（referenceconfig#destroy) #3502 
+* SPI entires dup by 3 times #3315 
+* fix Consumer throws RpcException after RegistryDirectory notify in high QPS #2016 
+* fix NPE in @Reference when using Junit to test dubbo service #3429 
+* fix consuer always catch java.lang.reflect.UndeclaredThrowableException for any exception throws in provider  #3386 
+* fix the priority of `DubboConfigConfigurationSelector ` #2897 
+* fix `@Rerefence#parameters()` not work #2301 
+
+## 2.6.5
+
+Enhancements / Features：    
+
+- Reactor the generation rule for @Service Bean name [#2235](https://github.com/apache/incubator-dubbo/issues/2235) 
+- Introduce a new Spring ApplicationEvent for ServiceBean exporting [#2251](https://github.com/apache/incubator-dubbo/issues/2251) 
+- [Enhancement] the algorithm of load issue on Windows. [#1641](https://github.com/apache/incubator-dubbo/issues/1641)
+- add javadoc to dubbo-all module good first issue. [#2600](https://github.com/apache/incubator-dubbo/issues/2600) 
+- [Enhancement] Reactor the generation rule for @Service Bean name type/enhancement [#2235](https://github.com/apache/incubator-dubbo/issues/2235) 
+- Optimize LeastActiveLoadBalance and add weight test case. [#2540](https://github.com/apache/incubator-dubbo/issues/2540) 
+- Smooth Round Robin selection. [#2578](https://github.com/apache/incubator-dubbo/issues/2578) [#2647](https://github.com/apache/incubator-dubbo/pull/2647) 
+- [Enhancement] Resolve the placeholders for sub-properties. [#2297](https://github.com/apache/incubator-dubbo/issues/2297) 
+- Add ability to turn off SPI auto injection, special support for generic Object type injection. [#2681](https://github.com/apache/incubator-dubbo/pull/2681)
+
+
+Bugfixes：    
+
+- @Service(register=false) is not work. [#2063](https://github.com/apache/incubator-dubbo/issues/2063) 
+- Our customized serialization id exceeds the maximum limit, now it cannot work on 2.6.2 anymore. [#1903](https://github.com/apache/incubator-dubbo/issues/1903) 
+- Consumer throws RpcException after RegistryDirectory notify in high QPS. [#2016](https://github.com/apache/incubator-dubbo/issues/2016)   
+- Annotation @Reference can't support to export a service with a sync one and an async one . [#2194](https://github.com/apache/incubator-dubbo/issues/2194) 
+- `org.apache.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor#generateReferenceBeanCacheKey` has a bug. [#2522](https://github.com/apache/incubator-dubbo/issues/2522) 
+- 2.6.x Spring Event & Bugfix. [#2256](https://github.com/apache/incubator-dubbo/issues/2256) 
+- Fix incorrect descriptions for dubbo-serialization module. [#2665](https://github.com/apache/incubator-dubbo/issues/2665) 
+- A empty directory dubbo-config/dubbo-config-spring/src/test/resources/work after package source tgz. [#2560](https://github.com/apache/incubator-dubbo/issues/2560)
+- Fixed 2.6.x branch a minor issue with doConnect not using getConnectTimeout() in NettyClient.  (*No issue*). [#2622](https://github.com/apache/incubator-dubbo/pull/2622) 
+- Bean name of @service annotated class does not resolve placeholder. [#1755](https://github.com/apache/incubator-dubbo/issues/1755) 
+
+
+
+Issues and Pull Requests, check [milestone-2.6.5](https://github.com/apache/incubator-dubbo/milestone/21).
+
+## 2.6.4
+
+Enhancements / Features
+
+- Support access Redis with password, [#2146](https://github.com/apache/incubator-dubbo/pull/2146)
+- Support char array for GenericService, [#2137](https://github.com/apache/incubator-dubbo/pull/2137)
+- Direct return when the server goes down abnormally, [#2451](https://github.com/apache/incubator-dubbo/pull/2451)
+- Add log for trouble-shooting when qos start failed, [#2455](https://github.com/apache/incubator-dubbo/pull/2455)
+- PojoUtil support subclasses of java.util.Date, [#2502](https://github.com/apache/incubator-dubbo/pull/2502)
+- Add ip and application name for MonitorService, [#2166](https://github.com/apache/incubator-dubbo/pull/2166)
+- New ASCII logo, [#2402](https://github.com/apache/incubator-dubbo/pull/2402)
+
+Bugfixes
+
+- Change consumer retries default value from 0 to 2, [#2303](https://github.com/apache/incubator-dubbo/pull/2303)
+- Fix the problem that attachment is lost when retry, [#2024](https://github.com/apache/incubator-dubbo/pull/2024)
+- Fix NPE when telnet get a null parameter, [#2453](https://github.com/apache/incubator-dubbo/pull/2453)
+
+UT stability
+
+- Improve the stability by changing different port, setting timeout to 3000ms, [#2501](https://github.com/apache/incubator-dubbo/pull/2501)
+
+Issues and Pull Requests, check [milestone-2.6.4](https://github.com/apache/incubator-dubbo/milestone/19).
+
+## 2.6.3
+
+Enhancements / Features
+
+- Support implicit delivery of attachments from provider to consumer, #889
+- Support inject Spring bean to SPI by bean type, #1837
+- Add generic invoke and attachments support for http&hessian protocol, #1827
+- Get the real methodname to support consistenthash for generic invoke, #1872
+- Remove validation key from provider url on Consumer side, config depedently, #1386
+- Introducing the Bootstrap module as a unified entry for Dubbo startup and resource destruction, #1820
+- Open TCP_NODELAY on Netty 3, #1746
+- Support specify proxy type on provider side, #1873
+- Support dbindex in redis, #1831
+- Upgrade tomcat to 8.5.31, #1781
+
+Bugfixes
+
+- ExecutionDispatcher meet with user docs, #1089
+- Remove side effects of Dubbo custom loggers on Netty logger, #1717
+- Fix isShutdown() judge of Dubbo biz threadpool always return true, #1426
+- Selection of invoker node under the critical condition of only two nodes, #1759
+- Listener cann't be removed during unsubscribe when use ZK as registry, #1792
+- URL parsing problem when user filed contains '@',  #1808
+- Check null in CacheFilter to avoid NPE, #1828
+- Fix potential deadlock in DubboProtocol, #1836
+- Restore the bug that attachment has not been updated in the RpcContext when the Dubbo built-in retry mechanism is triggered, #1453
+- Some other small bugfixes
+
+Performance Tuning
+
+- ChannelState branch prediction optimization. #1643
+- Optimize AtomicPositiveInteger, less memory and compute cost, #348
+- Introduce embedded Threadlocal to replace the JDK implementation, #1745
+
+Hessian-lite

internal-dubbo/CODE_OF_CONDUCT.md

+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at dev@dubbo.apache.org. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version]
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/

internal-dubbo/CONTRIBUTING.md

+
+## Contributing to dubbo
+Dubbo is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.
+
+### Sign the Contributor License Agreement
+Before we accept a non-trivial patch or pull request we will need you to sign the Contributor License Agreement. Signing the contributor’s agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. Active contributors might be asked to join the core team, and given the ability to merge pull requests.
+
+### Contact
+
+#### Mailing list
+
+The mailing list is the recommended way for discussing almost anything that related to Dubbo. Please refer to this [guide](https://github.com/apache/incubator-dubbo/wiki/Mailing-list-subscription-guide) for detailed documentation on how to subscribe.
+
+- [dev@dubbo.incubator.apache.org](mailto:dev-subscribe@dubbo.incubator.apache.org): the develop mailing list, you can ask question here if you have encountered any problem when using or developing Dubbo.
+- [commits@dubbo.incubator.apache.org](mailto:commits-subscribe@dubbo.incubator.apache.org): all the commits will be sent to this mailing list. You can subscribe to it if you are interested in Dubbo's development.
+- [notifications@dubbo.incubator.apache.org](mailto:notifications-subscribe@dubbo.incubator.apache.org): all the Github [issue](https://github.com/apache/incubator-dubbo/issues) updates and [pull request](https://github.com/apache/incubator-dubbo/pulls) updates will be sent to this mailing list.
+
+### Reporting issue
+
+Please follow the [template](https://github.com/apache/incubator-dubbo/issues/new?template=dubbo-issue-report-template.md) for reporting any issues.
+
+### Code Conventions
+Our code style is almost in line with the standard java conventions (Popular IDE's default setting satisfy this), with the following additional restricts:  
+* If there are more than 120 characters in current line, start a new line.
+
+* Make sure all new .java files to have a simple Javadoc class comment with at least a @date tag identifying birth, and preferably at least a paragraph on what the class is for.
+
+* Add the ASF license header comment to all new .java files (copy from existing files in the project)
+
+* Make sure no @author tag added to the file you contribute since @author tag is not used at Apache, other ways such as cvs will record all your contributions fairly.
+
+* Add some Javadocs and, if you change the namespace, some XSD doc elements.
+
+* A few unit tests should be added for a new feature or an important bugfix.
+
+* If no-one else is using your branch, please rebase it against the current master (or other target branch in the main project).
+
+* When writing a commit message please follow these conventions, if you are fixing an existing issue please add Fixes #XXX at the end of the commit message (where XXX is the issue number).
+
+### Contribution flow
+
+This is a rough outline of what a contributor's workflow looks like:
+
+* Fork the current repository
+* Create a topic branch from where to base the contribution. This is usually master.
+* Make commits of logical units.
+* Make sure commit messages are in the proper format (see below).
+* Push changes in a topic branch to your forked repository.
+* Follow the checklist in the [pull request template](https://github.com/apache/incubator-dubbo/blob/master/PULL_REQUEST_TEMPLATE.md)
+* Before you sending out the pull request, please sync your forked repository with remote repository, this will make your pull request simple and clear. See guide below:
+```
+git remote add upstream git@github.com:apache/incubator-dubbo.git
+git fetch upstream
+git rebase upstream/master
+git checkout -b your_awesome_patch
+... add some work
+git push origin your_awesome_patch
+```
+* Submit a pull request to apache/incubator-dubbo and wait for the reply.
+
+Thanks for contributing!
+
+### Code style
+
+We provide a template file [dubbo_codestyle_for_idea.xml](https://github.com/apache/incubator-dubbo/tree/master/codestyle/dubbo_codestyle_for_idea.xml) for IntelliJ idea, you can import it to you IDE. 
+If you use Eclipse you can config manually by referencing the same file.
+
+**NOTICE**
+
+It is very important to set the dubbo_codestyle_for_idea.xml, otherwise you will fail to pass the Travis CI. Steps to set the code style are as below:
+
+1. Enter `Editor > Code Style`
+2. To manage a code style scheme, in the Code Style page, select the desired scheme from the drop-down list, and click ![manage profiles](codestyle/manage_profiles.png).
+From the drop-down list, select `Import Scheme`, then select this option `IntelliJ IDEA code style XML` to import scheme
+3. In the Scheme field, type the name of the new scheme and press ⏎ to save the changes.
+

internal-dubbo/DISCLAIMER

+Apache Dubbo is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.
\ No newline at end of file

internal-dubbo/LICENSE

+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   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.
+
+
+Apache Dubbo Submodules:
+
+Apache Dubbo includes a number of submodules with separate copyright notices
+and license terms. Your use of these submodules is subject to the terms and
+conditions of the following licenses.
+
+For the package org.apache.dubbo.common.threadlocal and org.apache.dubbo.common.timer:
+
+This product contains a modified portion of 'Netty', an event-driven asynchronous network application framework also
+ under a "Apache License 2.0" license, see https://github.com/netty/netty/blob/4.1/LICENSE.txt:
+
+ * io.netty.util.concurrent.FastThreadLocal
+ * io.netty.util.internal.InternalThreadLocalMap
+ * io.netty.util.Timer
+ * io.netty.util.TimerTask
+ * io.netty.util.Timeout
+ * io.netty.util.HashedWheelTimer
+
+For the org.apache.dubbo.common.utils.CIDRUtils :
+
+This product contains a modified portion of 'edazdarevic.commons.net.CIDRUtils',
+ under a "MIT License" license, see https://github.com/edazdarevic/CIDRUtils/blob/master/CIDRUtils.java
+

internal-dubbo/NOTICE

+Apache Dubbo (incubating)
+Copyright 2018-2019 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+
+This product contains code form the Netty Project:
+
+The Netty Project
+=================
+Please visit the Netty web site for more information:
+  * http://netty.io/
+
+Copyright 2014 The Netty Project

internal-dubbo/PULL_REQUEST_TEMPLATE.md

+## What is the purpose of the change
+
+XXXXX
+
+## Brief changelog
+
+XXXXX
+
+## Verifying this change
+
+XXXXX
+
+Follow this checklist to help us incorporate your contribution quickly and easily:
+
+- [x] Make sure there is a [GITHUB_issue](https://github.com/apache/incubator-dubbo/issues) field for the change (usually before you start working on it). Trivial changes like typos do not require a GITHUB issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
+- [ ] Format the pull request title like `[Dubbo-XXX] Fix UnknownException when host config not exist #XXX`. Each commit in the pull request should have a meaningful subject line and body.
+- [ ] Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
+- [ ] Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add integration-test in [test module](https://github.com/apache/incubator-dubbo/tree/master/dubbo-test).
+- [ ] Run `mvn clean install -DskipTests=false` & `mvn clean test-compile failsafe:integration-test` to make sure unit-test and integration-test pass.
+- [ ] If this contribution is large, please follow the [Software Donation Guide](https://github.com/apache/incubator-dubbo/wiki/Software-donation-guide).

internal-dubbo/README.md

+# Apache Dubbo (incubating) Project
+
+[![Build Status](https://travis-ci.org/apache/incubator-dubbo.svg?branch=master)](https://travis-ci.org/apache/incubator-dubbo)
+[![codecov](https://codecov.io/gh/apache/incubator-dubbo/branch/master/graph/badge.svg)](https://codecov.io/gh/apache/incubator-dubbo)
+![maven](https://img.shields.io/maven-central/v/org.apache.dubbo/dubbo.svg)
+![license](https://img.shields.io/github/license/alibaba/dubbo.svg)
+[![Average time to resolve an issue](http://isitmaintained.com/badge/resolution/apache/incubator-dubbo.svg)](http://isitmaintained.com/project/apache/incubator-dubbo "Average time to resolve an issue")
+[![Percentage of issues still open](http://isitmaintained.com/badge/open/apache/incubator-dubbo.svg)](http://isitmaintained.com/project/apache/incubator-dubbo "Percentage of issues still open")
+[![Tweet](https://img.shields.io/twitter/url/http/shields.io.svg?style=social)](https://twitter.com/intent/tweet?text=Apache%20Dubbo%20(incubating)%20is%20a%20high-performance%2C%20java%20based%2C%20open%20source%20RPC%20framework.&url=http://dubbo.incubator.apache.org/&via=ApacheDubbo&hashtags=rpc,java,dubbo,micro-service)
+[![](https://img.shields.io/twitter/follow/ApacheDubbo.svg?label=Follow&style=social&logoWidth=0)](https://twitter.com/intent/follow?screen_name=ApacheDubbo)
+[![Gitter](https://badges.gitter.im/alibaba/dubbo.svg)](https://gitter.im/alibaba/dubbo?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+
+Apache Dubbo (incubating) is a high-performance, Java based open source RPC framework. Please visit [official site](http://dubbo.incubator.apache.org) for quick start and documentations, as well as [Wiki](https://github.com/apache/incubator-dubbo/wiki) for news, FAQ, and release notes.
+
+We are now collecting dubbo user info in order to help us to improve Dubbo better, pls. kindly help us by providing yours on [issue#1012: Wanted: who's using dubbo](https://github.com/apache/incubator-dubbo/issues/1012), thanks :)
+
+## Architecture
+
+![Architecture](http://dubbo.apache.org/img/architecture.png)
+
+## Features
+
+* Transparent interface based RPC
+* Intelligent load balancing
+* Automatic service registration and discovery
+* High extensibility
+* Runtime traffic routing
+* Visualized service governance
+
+## Getting started
+
+The following code snippet comes from [Dubbo Samples](https://github.com/apache/incubator-dubbo-samples/tree/master/dubbo-samples-api). You may clone the sample project and step into `dubbo-samples-api` sub directory before read on.
+
+```bash
+# git clone https://github.com/apache/incubator-dubbo-samples.git
+# cd incubator-dubbo-samples/dubbo-samples-api
+```
+
+There's a [README](https://github.com/apache/incubator-dubbo-samples/tree/master/dubbo-samples-api/README.md) file under `dubbo-samples-api` directory. Read it and try this sample out by following the instructions.
+
+### Maven dependency
+
+```xml
+<properties>
+    <dubbo.version>2.7.1</dubbo.version>
+</properties>
+    
+<dependencies>
+    <dependency>
+        <groupId>org.apache.dubbo</groupId>
+        <artifactId>dubbo</artifactId>
+        <version>${dubbo.version}</version>
+    </dependency>
+    <dependency>
+        <groupId>org.apache.dubbo</groupId>
+        <artifactId>dubbo-dependencies-zookeeper</artifactId>
+        <version>${dubbo.version}</version>
+        <type>pom</type>
+    </dependency>
+</dependencies>
+```
+
+### Define service interfaces
+
+```java
+package org.apache.dubbo.samples.api;
+
+public interface GreetingService {
+    String sayHello(String name);
+}
+```
+
+*See [api/GreetingService.java](https://github.com/apache/incubator-dubbo-samples/blob/master/dubbo-samples-api/src/main/java/org/apache/dubbo/samples/api/GreetingsService.java) on GitHub.*
+
+### Implement service interface for the provider
+
+```java
+package org.apache.dubbo.samples.provider;
+ 
+import org.apache.dubbo.samples.api.GreetingService;
+ 
+public class GreetingServiceImpl implements GreetingService {
+    @Override
+    public String sayHello(String name) {
+        return "Hello " + name;
+    }
+}
+```
+
+*See [provider/GreetingServiceImpl.java](https://github.com/apache/incubator-dubbo-samples/blob/master/dubbo-samples-api/src/main/java/org/apache/dubbo/samples/server/GreetingsServiceImpl.java) on GitHub.*
+
+### Start service provider
+
+```java
+package org.apache.dubbo.demo.provider;
+
+import org.apache.dubbo.config.ApplicationConfig;
+import org.apache.dubbo.config.RegistryConfig;
+import org.apache.dubbo.config.ServiceConfig;
+import org.apache.dubbo.samples.api.GreetingService;
+
+import java.io.IOException;
+ 
+public class Application {
+
+    public static void main(String[] args) throws IOException {
+        ServiceConfig<GreetingService> serviceConfig = new ServiceConfig<GreetingService>();
+        serviceConfig.setApplication(new ApplicationConfig("first-dubbo-provider"));
+        serviceConfig.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
+        serviceConfig.setInterface(GreetingService.class);
+        serviceConfig.setRef(new GreetingServiceImpl());
+        serviceConfig.export();
+        System.in.read();
+    }
+}
+```
+
+*See [provider/Application.java](https://github.com/apache/incubator-dubbo-samples/blob/master/dubbo-samples-api/src/main/java/org/apache/dubbo/samples/server/Application.java) on GitHub.*
+
+### Build and run the provider
+
+```bash
+# mvn clean package
+# mvn -Djava.net.preferIPv4Stack=true -Dexec.mainClass=org.apache.dubbo.demo.provider.Application exec:java
+```
+
+### Call remote service in consumer
+
+```java
+package org.apache.dubbo.demo.consumer;
+
+import org.apache.dubbo.config.ApplicationConfig;
+import org.apache.dubbo.config.ReferenceConfig;
+import org.apache.dubbo.config.RegistryConfig;
+import org.apache.dubbo.samples.api.GreetingService;
+
+public class Application {
+    public static void main(String[] args) {
+        ReferenceConfig<GreetingService> referenceConfig = new ReferenceConfig<GreetingService>();
+        referenceConfig.setApplication(new ApplicationConfig("first-dubbo-consumer"));
+        referenceConfig.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
+        referenceConfig.setInterface(GreetingService.class);
+        GreetingService greetingService = referenceConfig.get();
+        System.out.println(greetingService.sayHello("world"));
+    }
+}
+```
+
+### Build and run the consumer
+
+```bash
+# mvn clean package
+# mvn -Djava.net.preferIPv4Stack=true -Dexec.mainClass=org.apache.dubbo.demo.consumer.Application exec:java
+```
+
+The consumer will print out `Hello world` on the screen.
+
+*See [consumer/Application.java](https://github.com/apache/incubator-dubbo-samples/blob/master/dubbo-samples-api/src/main/java/org/apache/dubbo/samples/client/Application.java) on GitHub.*
+
+### Next steps
+
+* [Your first Dubbo application](http://dubbo.apache.org/en-us/blog/dubbo-101.html) - A 101 tutorial to reveal more details, with the same code above.
+* [Dubbo user manual](http://dubbo.apache.org/en-us/docs/user/preface/background.html) - How to use Dubbo and all its features.
+* [Dubbo developer guide](http://dubbo.apache.org/en-us/docs/dev/build.html) - How to involve in Dubbo development.
+* [Dubbo admin manual](http://dubbo.apache.org/en-us/docs/admin/install/provider-demo.html) - How to admin and manage Dubbo services.
+
+## Building
+
+If you want to try out the cutting-edge features, you can built with the following commands. (Java 1.8 is required to build the master branch)
+
+```
+  mvn clean install
+```
+
+## Contact
+
+* Mailing list: 
+  * dev list: for dev/user discussion. [subscribe](mailto:dev-subscribe@dubbo.incubator.apache.org), [unsubscribe](mailto:dev-unsubscribe@dubbo.incubator.apache.org), [archive](https://lists.apache.org/list.html?dev@dubbo.apache.org),  [guide](https://github.com/apache/incubator-dubbo/wiki/Mailing-list-subscription-guide)
+  
+* Bugs: [Issues](https://github.com/apache/incubator-dubbo/issues/new?template=dubbo-issue-report-template.md)
+* Gitter: [Gitter channel](https://gitter.im/alibaba/dubbo) 
+* Twitter: [@ApacheDubbo](https://twitter.com/ApacheDubbo)
+
+## Contributing
+
+See [CONTRIBUTING](https://github.com/apache/incubator-dubbo/blob/master/CONTRIBUTING.md) for details on submitting patches and the contribution workflow.
+
+### How can I contribute?
+
+* Take a look at issues with tag called [`Good first issue`](https://github.com/apache/incubator-dubbo/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) or [`Help wanted`](https://github.com/apache/incubator-dubbo/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22).
+* Join the discussion on mailing list, subscription [guide](https://github.com/apache/incubator-dubbo/wiki/Mailing-list-subscription-guide).
+* Answer questions on [issues](https://github.com/apache/incubator-dubbo/issues).
+* Fix bugs reported on [issues](https://github.com/apache/incubator-dubbo/issues), and send us pull request.
+* Review the existing [pull request](https://github.com/apache/incubator-dubbo/pulls).
+* Improve the [website](https://github.com/apache/incubator-dubbo-website), typically we need
+  * blog post
+  * translation on documentation
+  * use cases about how Dubbo is being used in enterprise system.
+* Improve the [dubbo-admin/dubbo-monitor](https://github.com/apache/incubator-dubbo-admin).
+* Contribute to the projects listed in [ecosystem](https://github.com/dubbo).
+* Any form of contribution that is not mentioned above.
+* If you would like to contribute, please send an email to dev@dubbo.incubator.apache.org to let us know!
+
+## Reporting bugs
+
+Please follow the [template](https://github.com/apache/incubator-dubbo/issues/new?template=dubbo-issue-report-template.md) for reporting any issues.
+
+## Reporting a security vulnerability
+
+Please report security vulnerability to [us](mailto:security@dubbo.incubator.apache.org) privately.
+
+## Dubbo ecosystem
+
+* [Dubbo Ecosystem Entry](https://github.com/dubbo) - A GitHub group `dubbo` to gather all Dubbo relevant projects not appropriate in [apache](https://github.com/apache) group yet
+* [Dubbo Website](https://github.com/apache/incubator-dubbo-website) - Apache Dubbo (incubating) official website
+* [Dubbo Samples](https://github.com/apache/incubator-dubbo-samples) - samples for Apache Dubbo (incubating)
+* [Dubbo Spring Boot](https://github.com/apache/incubator-dubbo-spring-boot-project) - Spring Boot Project for Dubbo
+* [Dubbo Admin](https://github.com/apache/incubator-dubbo-admin) - The reference implementation for Dubbo admin
+
+#### Language
+
+* [Node.js](https://github.com/dubbo/dubbo2.js)
+* [Python](https://github.com/dubbo/dubbo-client-py)
+* [PHP](https://github.com/dubbo/dubbo-php-framework)
+* [Go](https://github.com/dubbo/dubbo-go)
+* [Erlang](https://github.com/dubboerl/dubboerl)
+
+## License
+
+Apache Dubbo is under the Apache 2.0 license. See the [LICENSE](https://github.com/apache/incubator-dubbo/blob/master/LICENSE) file for details.

internal-dubbo/codestyle/checkstyle-suppressions.xml

+<?xml version="1.0"?>
+<!DOCTYPE suppressions PUBLIC
+        "-//Puppy Crawl//DTD Suppressions 1.1//EN"
+        "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
+<suppressions>
+    <suppress files="[\\/]src[\\/]main[\\/]java[\\/]com[\\/]alibaba[\\/]com[\\/]caucho[\\/]hessian" checks=".*"/>
+    <suppress files="Yylex\.java" checks="AvoidEscapedUnicodeCharacters"/>
+</suppressions>
\ No newline at end of file

internal-dubbo/codestyle/checkstyle.xml

+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+        "http://checkstyle.sourceforge.net/dtds/configuration_1_3.dtd">
+
+<module name="Checker">
+    <property name="charset" value="UTF-8"/>
+    <property name="fileExtensions" value="java"/>
+
+    <!-- TreeWalker Checks -->
+    <module name="TreeWalker">
+        <module name="SuppressWarningsHolder"/>
+
+        <module name="AvoidStarImport"/>
+        <module name="AvoidEscapedUnicodeCharacters">
+            <property name="allowEscapesForControlCharacters" value="true"/>
+            <property name="allowByTailComment" value="true"/>
+            <property name="allowNonPrintableEscapes" value="true"/>
+        </module>
+        <module name="NoLineWrap"/>
+        <module name="OuterTypeFilename"/>
+        <module name="UnusedImports"/>
+        <module name="RedundantImport"/>
+
+        <!--<module name="CustomImportOrder">-->
+        <!--<property name="specialImportsRegExp" value="org.apache.dubbo.*"/>-->
+        <!--<property name="sortImportsInGroupAlphabetically" value="false"/>-->
+        <!--<property name="customImportOrderRules" value="SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE###STANDARD_JAVA_PACKAGE###STATIC"/>-->
+        <!--</module>-->
+    </module>
+</module>
\ No newline at end of file

internal-dubbo/codestyle/dubbo_codestyle_for_idea.xml

+<code_scheme name="dubbo_codestyle">
+    <option name="CLASS_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99"/>
+    <option name="NAMES_COUNT_TO_USE_IMPORT_ON_DEMAND" value="99"/>
+    <option name="IMPORT_LAYOUT_TABLE">
+        <value>
+            <package name="org.apache.dubbo" withSubpackages="true" static="false"/>
+            <emptyLine/>
+            <package name="" withSubpackages="true" static="false"/>
+            <emptyLine/>
+            <package name="javax" withSubpackages="true" static="false"/>
+            <package name="java" withSubpackages="true" static="false"/>
+            <emptyLine/>
+            <package name="" withSubpackages="true" static="true"/>
+        </value>
+    </option>
+</code_scheme>
\ No newline at end of file

internal-dubbo/dubbo-bom/pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.apache.dubbo</groupId>
+        <artifactId>dubbo-parent</artifactId>
+        <version>${revision}</version>
+    </parent>
+
+    <artifactId>dubbo-bom</artifactId>
+    <packaging>pom</packaging>
+
+    <name>dubbo-bom</name>
+    <description>Dubbo dependencies BOM</description>
+    <url>https://github.com/apache/incubator-dubbo</url>
+    <inceptionYear>2011</inceptionYear>
+    <licenses>
+        <license>
+            <name>Apache License, Version 2.0</name>
+            <url>http://www.apache.org/licenses/LICENSE-2.0</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+
+    <scm>
+        <url>https://github.com/apache/incubator-dubbo</url>
+        <connection>scm:git:https://github.com/apache/incubator-dubbo.git</connection>
+        <developerConnection>scm:git:https://github.com/apache/incubator-dubbo.git</developerConnection>
+      <tag>HEAD</tag>
+  </scm>
+    <mailingLists>
+        <mailingList>
+            <name>Development List</name>
+            <subscribe>dev-subscribe@dubbo.apache.org</subscribe>
+            <unsubscribe>dev-unsubscribe@dubbo.apache.org</unsubscribe>
+            <post>dev@dubbo.apache.org</post>
+        </mailingList>
+        <mailingList>
+            <name>Commits List</name>
+            <subscribe>commits-subscribe@dubbo.apache.org</subscribe>
+            <unsubscribe>commits-unsubscribe@dubbo.apache.org</unsubscribe>
+            <post>commits@dubbo.apache.org</post>
+        </mailingList>
+        <mailingList>
+            <name>Issues List</name>
+            <subscribe>issues-subscribe@dubbo.apache.org</subscribe>
+            <unsubscribe>issues-unsubscribe@dubbo.apache.org</unsubscribe>
+            <post>issues@dubbo.apache.org</post>
+        </mailingList>
+    </mailingLists>
+    <developers>
+        <developer>
+            <id>dubbo.io</id>
+            <name>The Dubbo Project Contributors</name>
+            <email>dev-subscribe@dubbo.apache.org</email>
+            <url>http://dubbo.apache.org/</url>
+        </developer>
+    </developers>
+
+    <organization>
+        <name>The Apache Software Foundation</name>
+        <url>http://www.apache.org/</url>
+    </organization>
+
+    <issueManagement>
+        <system>Github Issues</system>
+        <url>https://github.com/apache/incubator-dubbo/issues</url>
+    </issueManagement>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-cluster</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-common</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-config-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-config-spring</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-filter-cache</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-filter-validation</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-netty</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-netty4</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-mina</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-grizzly</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-p2p</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-http</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-remoting-etcd3</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-dubbo</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-injvm</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-jsonrpc</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-rmi</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-hessian</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-http</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-webservice</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-thrift</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-memcached</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-redis</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-rpc-rest</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-default</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-multicast</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-zookeeper</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-redis</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-etcd3</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-consul</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-registry-sofa</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-monitor-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-monitor-default</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-container-spring</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-container-log4j</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-container-logback</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-qos</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-fastjson</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-fst</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-hessian2</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-jdk</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-kryo</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-protostuff</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-avro</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-serialization-gson</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-compatible</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-report-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-report-zookeeper</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-report-redis</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-report-consul</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-report-etcd</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-configcenter-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-configcenter-zookeeper</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-configcenter-apollo</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-configcenter-consul</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-configcenter-etcd</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.apache.dubbo</groupId>
+                <artifactId>dubbo-metadata-definition</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <profiles>
+        <profile>
+            <id>release</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-gpg-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>verify</phase>
+                                <goals>
+                                    <goal>sign</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+</project>

internal-dubbo/dubbo-cluster/pom.xml

+<!--
+  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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.apache.dubbo</groupId>
+        <artifactId>dubbo-parent</artifactId>
+        <version>${revision}</version>
+    </parent>
+    <artifactId>dubbo-cluster</artifactId>
+    <packaging>jar</packaging>
+    <name>${project.artifactId}</name>
+    <description>The cluster module of dubbo project</description>
+    <properties>
+        <skip_maven_deploy>false</skip_maven_deploy>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-rpc-api</artifactId>
+            <version>${project.parent.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-configcenter-api</artifactId>
+            <version>${project.parent.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.yaml</groupId>
+            <artifactId>snakeyaml</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.curator</groupId>
+            <artifactId>curator-framework</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.zookeeper</groupId>
+            <artifactId>zookeeper</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>
\ No newline at end of file

internal-dubbo/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/CacheableRouterFactory.java

+/*
+ * 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.rpc.cluster;
+
+import org.apache.dubbo.common.URL;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * If you want to provide a router implementation based on design of v2.7.0, please extend from this abstract class.
+ * For 2.6.x style router, please implement and use RouterFactory directly.
+ */
+public abstract class CacheableRouterFactory implements RouterFactory {
+    private ConcurrentMap<String, Router> routerMap = new ConcurrentHashMap<>();
+
+    @Override
+    public Router getRouter(URL url) {
+        routerMap.computeIfAbsent(url.getServiceKey(), k -> createRouter(url));
+        return routerMap.get(url.getServiceKey());
+    }
+
+    protected abstract Router createRouter(URL url);
+}

internal-dubbo/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/Cluster.java

+/*
+ * 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.rpc.cluster;
+
+import org.apache.dubbo.common.extension.Adaptive;
+import org.apache.dubbo.common.extension.SPI;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.support.FailoverCluster;
+
+/**
+ * Cluster. (SPI, Singleton, ThreadSafe)
+ * <p>
+ * <a href="http://en.wikipedia.org/wiki/Computer_cluster">Cluster</a>
+ * <a href="http://en.wikipedia.org/wiki/Fault-tolerant_system">Fault-Tolerant</a>
+ *
+ */
+@SPI(FailoverCluster.NAME)
+public interface Cluster {
+
+    /**
+     * Merge the directory invokers to a virtual invoker.
+     *
+     * @param <T>
+     * @param directory
+     * @return cluster invoker
+     * @throws RpcException
+     */
+    @Adaptive
+    <T> Invoker<T> join(Directory<T> directory) throws RpcException;
+
+}
\ No newline at end of file

internal-dubbo/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/Configurator.java

+/*
+ * 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.rpc.cluster;
+
+import org.apache.dubbo.common.Constants;
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.common.extension.ExtensionLoader;
+import org.apache.dubbo.common.utils.CollectionUtils;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Configurator. (SPI, Prototype, ThreadSafe)
+ *
+ */
+public interface Configurator extends Comparable<Configurator> {
+
+    /**
+     * Get the configurator url.
+     *
+     * @return configurator url.
+     */
+    URL getUrl();
+
+    /**
+     * Configure the provider url.
+     *
+     * @param url - old provider url.
+     * @return new provider url.
+     */
+    URL configure(URL url);
+
+
+    /**
+     * Convert override urls to map for use when re-refer. Send all rules every time, the urls will be reassembled and
+     * calculated
+     *
+     * URL contract:
+     * <ol>
+     * <li>override://0.0.0.0/...( or override://ip:port...?anyhost=true)&para1=value1... means global rules
+     * (all of the providers take effect)</li>
+     * <li>override://ip:port...?anyhost=false Special rules (only for a certain provider)</li>
+     * <li>override:// rule is not supported... ,needs to be calculated by registry itself</li>
+     * <li>override://0.0.0.0/ without parameters means clearing the override</li>
+     * </ol>
+     *
+     * @param urls URL list to convert
+     * @return converted configurator list
+     */
+    static Optional<List<Configurator>> toConfigurators(List<URL> urls) {
+        if (CollectionUtils.isEmpty(urls)) {
+            return Optional.empty();
+        }
+
+        ConfiguratorFactory configuratorFactory = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
+                .getAdaptiveExtension();
+
+        List<Configurator> configurators = new ArrayList<>(urls.size());
+        for (URL url : urls) {
+            if (Constants.EMPTY_PROTOCOL.equals(url.getProtocol())) {
+                configurators.clear();
+                break;
+            }
+            Map<String, String> override = new HashMap<>(url.getParameters());
+            //The anyhost parameter of override may be added automatically, it can't change the judgement of changing url
+            override.remove(Constants.ANYHOST_KEY);
+            if (override.size() == 0) {
+                configurators.clear();
+                continue;
+            }
+            configurators.add(configuratorFactory.getConfigurator(url));
+        }
+        Collections.sort(configurators);
+        return Optional.of(configurators);
+    }
+
+    /**
+     * Sort by host, then by priority
+     * 1. the url with a specific host ip should have higher priority than 0.0.0.0
+     * 2. if two url has the same host, compare by priority value；
+     */
+    @Override
+    default int compareTo(Configurator o) {
+        if (o == null) {
+            return -1;
+        }
+
+        int ipCompare = getUrl().getHost().compareTo(o.getUrl().getHost());
+        // host is the same, sort by priority
+        if (ipCompare == 0) {
+            int i = getUrl().getParameter(Constants.PRIORITY_KEY, 0);
+            int j = o.getUrl().getParameter(Constants.PRIORITY_KEY, 0);
+            return Integer.compare(i, j);
+        } else {
+            return ipCompare;
+        }
+    }
+}

internal-dubbo/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/ConfiguratorFactory.java

+/*
+ * 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.rpc.cluster;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.common.extension.Adaptive;
+import org.apache.dubbo.common.extension.SPI;
+
+/**
+ * ConfiguratorFactory. (SPI, Singleton, ThreadSafe)
+ *
+ */
+@SPI
+public interface ConfiguratorFactory {
+
+    /**
+     * get the configurator instance.
+     *
+     * @param url - configurator url.
+     * @return configurator instance.
+     */
+    @Adaptive("protocol")
+    Configurator getConfigurator(URL url);
+
+}

internal-dubbo/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/Directory.java

+/*
+ * 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.rpc.cluster;
+
+import org.apache.dubbo.common.Node;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcException;
+
+import java.util.List;
+
+/**
+ * Directory. (SPI, Prototype, ThreadSafe)
+ * <p>
+ * <a href="http://en.wikipedia.org/wiki/Directory_service">Directory Service</a>
+ *
+ * @see org.apache.dubbo.rpc.cluster.Cluster#join(Directory)
+ */
+public interface Directory<T> extends Node {
+
+    /**
+     * get service type.
+     *
+     * @return service type.
+     */
+    Class<T> getInterface();
+
+    /**
+     * list invokers.
+     *
+     * @return invokers
+     */
+    List<Invoker<T>> list(Invocation invocation) throws RpcException;
+
+}
\ No newline at end of file