Shulou(Shulou.com)06/03 Report--

What is Nacos?

To quote the official introduction, he mainly provides the following functional points:

Dynamic configuration service discovery and management of dynamic DNS service

Dynamic configuration service

It is through a system to manage the configuration items in the system. When the configuration items need to be updated, you can operate the update through the management system. After the update is finished, it will actively push to the client that subscribes to this configuration.

Specific use scenarios, for example, in the system, there will be database link strings, account passwords and other configuration information, the general practice is to write in the configuration file, if you need to modify and update, you need to repackage and compile, if you are a distributed cluster, it is too expensive, usually we will extract it and store it in db, or a management system, Nacos, is this management system Nacos also provides the ability to notify actively. DB does not have it. In your own system code, you can monitor a configuration. If you modify the configuration item on the management system, the client's listening function will be executed immediately. Inside, you can get the latest configuration and execute your own business logic.

Service Discovery and Management

This is mainly aimed at the distributed micro-service cluster system, one A cluster provides services, other application clusters need to consume services to A cluster, need a system to manage the ip list of A cluster, other application clusters, go to this system to get the ip list of A cluster and call it. At the same time, the system needs to be able to automatically remove the ip that does not work in A cluster. This is the only way to ensure the success of the caller. Nacos is a system that provides this capability.

Dynamic DNS service

This is also easy to understand. We usually visit an api of a http in the code, usually with a domain name. When making a request, we usually go to the DNS domain name server to find the ip corresponding to the domain name, and then initiate a http request. What are the advantages that Nacos can play the role of this DNS domain name server? Nacos provides more convenient management capabilities than DNS domain name server. A new domain name only needs to be configured on the console of Nacos. At the same time, it also provides capabilities that DNS servers do not have, including weights, health checks, attributes, routing and other capabilities, which are much more powerful than DNS's product features, stability and flexibility.

In addition to solving some of the scenarios mentioned above, Nacos is free to play, anyway, its ability is there, as for how to use it, it depends on your smart head.

Next, we try to pull a copy from the official source code of Nacos and carry out a simple process of publishing and subscribing to the service, so that we can feel the function of Nacos more.

Download the source code

The code for Nacos is hosted on github, https://github.com/alibaba/nacos

Take a look at start before you start, plus watch, and the subsequent Nacos mailing list will also notify you to follow the latest real-time news from Nacos.

First of all, we directly download the source code of Nacos to the local address as shown below:

Then, to pull the code from github, the command is as follows:

Git clone git@github.com:alibaba/nacos.git

After execution, the progress shown below appears.

Compilation start

After downloading, there will be a nacos folder locally. After entering it, execute the command to compile and package:

Mvn-Prelease-nacos clean install-U-Dmaven.test.skip=true

After execution, the following project files will be generated in the nacos/distribution/target folder:

Ignore archive-tmp and copy nacos-server-0.2.0.zip or nacos-server-0.2.0.tar.gz directly to your server

Then unpack it and get a folder called nacos, which has the following structure:

Enter the bin file, where there is a script for starting and shutting down nacos server. Let's execute the startup script. Note that there are two ways to start nacos server. One is cluster mode and the other is stand-alone mode. Since cluster mode requires some other configurations to run, we need to add a special parameter to stand-alone mode today. The command is as follows:

Sh startup.sh-m standalone

After the command is executed, a prompt appears:

Nacos is starting,you can check the / home/caogu.wyp/test/nacos/logs/start.log

We can go to / nacos/logs/start.log to check the startup log to see if there is an error. If there is an error, we can analyze it ourselves. If we can't find the reason, contact the Nacos administrator @ Brother Chao, and he will be eager to help you solve the problem.

The log of successful startup is as follows:

At the same time, we can also check whether the port of server under check is listening successfully and execute

Netstat-ano | grep 8080

Publish a service

We now use the Java client to publish and subscribe to a service. The client can be run in two ways. One is downloaded from the maven coordinates in our own project, and the other is directly from the downloaded Nacos source code. The coordinates are as follows:

Com.alibaba.nacosnacos-client0.1.0

Since we have the code, I will operate directly in the project. The structure of the project is as follows. Create a new helloworld package in the test module:

In the Pub class, publish a piece of data with the following code:

Public class Pub {public static void main (String [] args) throws NacosException, InterruptedException {/ / published service name String serviceName = "helloworld.services"; / / construct a nacos instance with input parameters of nacos server ip and service port NamingService naming = NamingFactory.createNamingService ("100.81.0.34 NamingService naming 8080") / / publish a service with an ip of 127.0.0.1 and a port of 8888 naming.registerInstance (serviceName, "127.0.0.1", 8888); Thread.sleep (Integer.MAX_VALUE);}}

After startup, the service has been released.

Subscribe to a service

Here is the code for Sub:

Public class Sub {public static void main (String [] args) throws NacosException, InterruptedException {/ / subscribed service name String serviceName = "helloworld.services"; / / create a nacos instance NamingService naming = NamingFactory.createNamingService ("100.81.0.34) 8080") / subscribe to a service naming.subscribe (serviceName, event-> {if (event instanceof NamingEvent) {System.out.println ("subscribe to data"); System.out.println (NamingEvent) event) .getInstances ();}}); System.out.println ("subscription completed, ready, etc.") Thread.sleep (Integer.MAX_VALUE);}}

If we try to start it, we will subscribe to the data just released:

Summary

The above process is a helloworld service publication and subscription, which is simple enough. In the actual production environment, several ip services are often hung under a service. At the subscriber end, after getting all the address lists under the service, select an ip to call through the load balance strategy, such as random policy, so that a remote call is completed.

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