Zookeeper--java Client

I. Zookeeper INTRODUCTION

A coordinated service system for managing distributed Applications

Two. Zookeeper Application scenario

There are also many introductions on the internet, see http://blog.csdn.net/xinguan1267/article/details/38422149

This article mainly introduces the Java-based client development

Three. Based on Java client combat

3.1Client

  Create a connection to the server   needs ( ip+ port number on the service side) (Session Expiration Time) (Watcher Monitor Registration)   zookeeper zk =  new zookeeper ("10.154.156.180:2181",          3000,  new watcher ()  {             / /  monitors all triggered events public void process (watchedevent event)  {// todo auto-generated  method stubsystem.out.println ("has triggered"  + event.gettype ()  +  "Event! ");  }   }); //  Create a directory node  /**  * createmode:  *  PERSISTENT  (persistent, relative to ephemeral, does not disappear with the disconnection of the client)   *persistent_sequential (persistent and sequential)    *EPHEMERAL  (short, life cycle dependent on client session)   *EPHEMERAL_SEQUENTIAL   (short, sequential)   */ zk.create ("/testrootpath",  "Testrootdata". GetBytes (),  ids.open_acl_unsafe, Createmode.persistent);   // Create a subdirectory node  zk.create ("/testrootpath/testchildpathone",  "Testchilddataone". GetBytes (), Ids.open_acl_ unsafe,createmode.persistent);   system.out.println (New string (Zk.getdata ("/testRootPath", false, NULL));   //  Remove the subdirectory node list  system.out.println (Zk.getchildren ("/testrootpath", true));    //  Create another subdirectory node  zk.create ("/testrootpath/testchildpathtwo",  "Testchilddatatwo" . GetBytes (),  ids.open_acl_unsafe,createmode.persistent);    system.out.println ( Zk.getchildren ("/testrootpath", true));  //  modifies the subdirectory node data  zk.setdata ("/testrootpath/ Testchildpathone "," Hahahahaha ". GetBytes (), -1);     byte[] datas = zk.getdata ("/testrootpath/testchildpathone",  true, null);  string str = new string ( Datas, "Utf-8");  system.out.println (str);    //Delete entire subdirectory    -1 represents version number,- 1 is to remove all versions of  zk.delete ("/testrootpath/testchilDpathone ",  -1);   system.out.println (Zk.getchildren ("/testrootpath ", True);   System.out.println (str);

Some examples can be found in the official website api:http://zookeeper.apache.org/doc/r3.2.2/api/org/apache/zookeeper/zookeeper.html#create% 28java.lang.string,%20byte%5b%5d,%20java.util.list,%20org.apache.zookeeper.createmode%29

3.2 curator

The Curator Framework provides an advanced set of APIs that simplifies the operation of zookeeper. It adds a lot of features developed using zookeeper to handle complex connection management and retry mechanisms for zookeeper clusters. These features include:

• Encapsulates the connection processing between the zookeeper client and the zookeeper server;

• Provides a set of fluent style of Operation API;

• Abstract encapsulation of zookeeper various application scenarios (recipe, such as shared Lock service, cluster leader election mechanism) is provided.

• The fluent style can be viewed in one of my blog (builder mode), I look at ES search source found that also used the fluent style.

• Here's how to create an object using curator

• public static curatorframework  Createwithoptions (string connectionstring, retrypolicy retrypolicy, int  CONNECTIONTIMEOUTMS, INT SESSIONTIMEOUTMS)  {                 return curatorframeworkfactory.builder (). ConnectString ( connectionString)                  .retrypolicy (Retrypolicy)                  .connectiontimeoutms (CONNECTIONTIMEOUTMS)                  .sessiontimeoutms (SESSIONTIMEOUTMS)                  .build ();     } 

The calling code is as follows:

Client = Createwithoptions ("10.154.156.180:2181", New Exponentialbackoffretry (3), +, +); Client.start ();

If you need to create a new directory node is still a fluent style

Client.create (). Forpath ("/curator", New Byte[0]), Client.create (). Withmode (createmode.persistent). ForPath ("/ Curator/childone ", new byte[0]);

Of course create ZK can also not use fluent style

public static Curatorframework Createsimple (String connectionString) {exponentialbackoffretry retrypolicy                = new Exponentialbackoffretry (1000, 3); Return Curatorframeworkfactory.newclient (connectionString, retrypolicy);}

Other ways to explain:

• Create (): Initiates a create operation. You can combine other methods (such as mode or background) and end with the Forpath () method

• Delete (): Initiates a delete operation. You can combine other methods (version or background) and end with the Forpath () method

• Checkexists (): Initiates an action to check whether the Znode exists. You can combine other methods (watch or background) and end with the Forpath () method

• GetData (): Initiates an operation to get Znode data. You can combine other methods (watch, background, or get stat) and end with the Forpath () method

• SetData (): Initiates an operation to set Znode data. You can combine other methods (version or background) and end with the Forpath () method

• GetChildren (): Initiates an operation to get the Znode child node. You can combine other methods (watch, background, or get stat) and end with the Forpath () method

• Intransaction (): Initiates a zookeeper transaction. You can combine create, setData, check, and/or delete as an action, and commit () commit

Zookeeper--java Client