Example and Problem Analysis of Using Coprocessor Proxy in Hbase Endpoint coprocessor

Example and Problem Analysis of Using Coprocessor Proxy in Hbase Endpoint coprocessor

1. Note the following:

1. There are three methods to start Coprocessor: configuration file, shell, and program. I use the program to specify:

 

    static {        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());        family.setInMemory(true);        family.setMaxVersions(1);        EP_TABLE_DISCRIPTOR.addFamily(family);        try {            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");        } catch (IOException ioe) {        }

In the code above, addCoprocessor specifies that the table starts the coprocessor operation. But the premise is that HBase must be restarted.To load the jar package.

 

2. If the following problem occurs after the client connection: No matching handler *** for protocol in *** region, it means that the jar package has not been loaded into elasticsearch and HBase has been restarted, in addition, check addCoprocessor ("ict. wde. test. rowCountServer "); is the class name" RowCountServer "correctly written?

Ii. Next steps

2.1 write the server code:

1) Interface Class (fixed format)

 

package ict.wde.test;import org.apache.hadoop.hbase.Coprocessor;import org.apache.hadoop.hbase.filter.Filter;import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;import java.io.File;import java.io.IOException;/** * Created by Michael on 2015/6/22. */public interface RowCountProtocol extends Coprocessor, CoprocessorProtocol {    public long getRowCount() throws IOException;    public long getRowCount(Filter filter) throws IOException;    public String getStr() throws IOException;    //public long getKeyValue() throws IOException;}

2) classes that actually work

package ict.wde.test;import org.apache.hadoop.hbase.CoprocessorEnvironment;import org.apache.hadoop.hbase.client.Scan;import org.apache.hadoop.hbase.filter.Filter;import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;import org.apache.hadoop.hbase.ipc.ProtocolSignature;import java.io.IOException;/** * Created by Michael on 2015/6/27. */public class RowCountServer implements RowCountProtocol {    @Override    public void start(CoprocessorEnvironment env) throws IOException {    }    @Override    public void stop(CoprocessorEnvironment env) throws IOException {    }    @Override    public ProtocolSignature getProtocolSignature(String protocol,                                                  long clientVersion, int clientMethodsHash) throws IOException {        return new ProtocolSignature(3, null);    }    @Override    public long getProtocolVersion(String protocol, long clientVersion) throws IOException {        return 3;    }    @Override    public long getRowCount() throws IOException {        return this.getRowCount(new FirstKeyOnlyFilter());    }    @Override    public long getRowCount(Filter filter) throws IOException {        return this.getRowCount(filter, false);    }    @Override    public String getStr() throws IOException {        String name = "Hello Doctor Michael Zhang, again!";        return name;    }//    @Override//    public long getKeyValueCount() {//        return 0;//    }    public long getRowCount(Filter filter, boolean countKeyValue) throws IOException {        Scan scan = new Scan();        scan.setMaxVersions(1);        if (filter != null) {            scan.setFilter(filter);        }        return 1;    }}

Package the jar files of the preceding two classes and put them in the lib directory of hbase.

 

2.2 client code

 

import ict.wde.test.RowCountProtocol;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.hbase.HColumnDescriptor;import org.apache.hadoop.hbase.HTableDescriptor;import org.apache.hadoop.hbase.client.HBaseAdmin;import org.apache.hadoop.hbase.client.HTable;import org.apache.hadoop.hbase.client.HTableInterface;import org.apache.hadoop.hbase.filter.Filter;import java.io.IOException;/** * Created by Michael on 2015/6/30. */public class EndpointTestClient {    private final HTableInterface table;    private final Configuration conf;    private final RowCountProtocol server;    private static final HTableDescriptor EP_TABLE_DISCRIPTOR;    static {        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());        family.setInMemory(true);        family.setMaxVersions(1);        EP_TABLE_DISCRIPTOR.addFamily(family);        try {            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");        } catch (IOException ioe) {        }    }    public EndpointTestClient(Configuration config) throws IOException {        conf = config;        table = initTidTable();        server = table.coprocessorProxy(RowCountProtocol.class, "0".getBytes());    }    private HTableInterface initTidTable() throws IOException {        HBaseAdmin admin = new HBaseAdmin(conf);        if (!admin.tableExists("epTest")) {            admin.createTable(EP_TABLE_DISCRIPTOR);        }        admin.close();        return new HTable(conf, "epTest");    }    public String getStr() throws IOException {        return server.getStr();    }}

Startup class:

import org.apache.hadoop.conf.Configuration;import java.io.IOException;/** * Created by Michael on 2015/6/22. */public class EndpointExample {//    private final HTableInterface table;//    private static final Configuration conf;//    private static final HTableDescriptor EP_TABLE_DISCRIPTOR;////    static {//        conf = new Configuration();//        conf.set("hbase.zookeeper.quorum", "ccf04:2181");////        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");//        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());//        family.setInMemory(true);//        family.setMaxVersions(1);//        EP_TABLE_DISCRIPTOR.addFamily(family);//        try {//            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");//        } catch (IOException ioe) {////        }////        table = initTidTable();//    }////    private HTableInterface initTidTable() throws IOException {//        HBaseAdmin admin = new HBaseAdmin(conf);//        if (!admin.tableExists("epTest")) {//            admin.createTable(EP_TABLE_DISCRIPTOR);//        }//        admin.close();//        return new HTable(conf, "epTest");//    }    public static void main(String[] agrs) throws IOException {        Configuration conf = new Configuration();        conf.set("hbase.zookeeper.quorum", "ccf04:2181");        EndpointTestClient client = new EndpointTestClient(conf);        String name = client.getStr();        System.out.println(name);    }}