基于Thrift实现跨语言服务

悠悠 2022-06-16 06:38 201阅读 0赞

假设，现在我们有这样一个需求：   
要通过一个代理平台，将查询请求转发到后端服务器进行查询。后端存在多种查询服务器，查询方式也不同，比如，有基于SQL的关系数据库查询，也有基于搜索引擎Solr的查询。通过代理平台，将服务暴露给具有任何编程语言技能的开发人员进行调用。   
我们可以选择Thrift来定义语言中性的服务接口，然后通过Thrift编译器将定义生成多种编程语言的客户端代码框架，服务器端使用指定语言进行开发，如Java，最后通过连接Thrift服务器来进行查询调用。   
根据我们的需求，后端服务使用Java实现，而外部使用C\#进行调用返回结果，再执行进一步的处理。

Thrift服务定义

首先，看一下，我们给出的示例服务定义，文件命名为queryproxy.thrift，内容如下所示：

namespace java org.shirdrn.queryproxy.thrift.protocol
    namespace csharp Query.Proxy.Thrift.Protocol
    namespace py queryproxy.thrift.protocol
    
    typedef i16 short
    typedef i32 int
    typedef i64 long
    
    enum QueryType {
         SOLR = 1,
         SQL = 2
    }
    
    struct QueryParams {
         1:QueryType type,
         2:string table,
         3:list<string> paramList
    }
    
    struct QueryResult {
         1:int offset,
         2:int length
         3:list<string> results
    }
    
    exception QueryFailureException {
      1:string message
    }
    
    service QueryProxyService {
    
         QueryResult query(1:QueryParams paramList) throws (1:QueryFailureException qe)
         
    }

上面定义的内容的含义如下所示：

*  QueryType 指定查询类型，包括两种类型：查询Solr服务器，或SQL查询
 *  QueryParams 用来设置请求参数
 *  QueryResult 是返回结果对象，封装了查询结果列表，我们将查询结果以JSON列表形式返回
 *  QueryFailureException 如果查询失败，返回该异常
 *  QueryProxyService 定义了服务调用接口

编译Thrift服务定义

根据上面定义的服务，使用Thrift编译器生成不同编程语言的代码，我们生成用于服务器端的Java代码，和客户端服务调用的C\#代码，执行命令如下所示：

thrift --gen java queryproxy.thrift
    thrift --gen csharp queryproxy.thrift

然后可以在当前目录下面查看到编译生成的代码目录：

ls
    gen-csharp  gen-java

可以直接基于这些代码进行开发服务器端和客户端代码，详见后面说明。

Thrift服务实现

我们使用Java语言实现服务器端的Thrift服务。首先，需要从Thrift的发行包中给出的jar文件，添加到classpath中，基于该库文件进行服务开发。   
通过上一步使用Thrift编译器编译生成的Java代码，可以看到一个服务接口：

org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Iface

我们要对两种类型的查询服务（Solr和SQL）给出实现，首先基于该服务接口来抽象出一层，在抽象类中定义了服务配置对象（读取Properties文件），其中配置文件内容大概如下所示：

query.proxy.thrift.port=9966
    query.proxy.thrift.worker.thread.minCount=1
    query.proxy.thrift.worker.thread.maxCount=200
    query.proxy.solr.zkHost=master:2181

抽象服务类如下所示：

package org.shirdrn.queryproxy.common;
    
    import java.io.Closeable;
    
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Iface;
    
    public abstract class ConfiguredQueryService implements Iface, Closeable {
         
         protected final Configurable context;
         
         public ConfiguredQueryService(Configurable context) {
              super();
              this.context = context;
         }
    }

然后实现上面提到的两种类型的服务，都基于该抽象类进行开发。

*  Solr查询服务实现

因为后端已经存在一个Solr查询服务器集群（SolrCloud），我们实际上是通过solrj客户端调用来执行查询，所以Thrift服务端的查询也是基于这个原理。下面，看一下Solr查询服务实现类SolrQueryService的实现内容，代码如下所示：

package org.shirdrn.queryproxy.thrift.service.solr;
    
    import java.io.IOException;
    import java.net.MalformedURLException;
    import java.util.HashMap;
    import java.util.Iterator;
    import java.util.Map;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.solr.client.solrj.SolrServerException;
    import org.apache.solr.client.solrj.impl.CloudSolrServer;
    import org.apache.solr.client.solrj.response.QueryResponse;
    import org.apache.solr.common.params.CommonParams;
    import org.apache.solr.common.params.MapSolrParams;
    import org.apache.solr.common.params.SolrParams;
    import org.apache.thrift.TException;
    import org.shirdrn.queryproxy.common.Configurable;
    import org.shirdrn.queryproxy.common.ConfiguredQueryService;
    import org.shirdrn.queryproxy.thrift.protocol.QueryFailureException;
    import org.shirdrn.queryproxy.thrift.protocol.QueryParams;
    import org.shirdrn.queryproxy.thrift.protocol.QueryResult;
    import org.shirdrn.queryproxy.utils.ResultUtils;
    
    public class SolrQueryService extends ConfiguredQueryService {
    
         private static final Log LOG = LogFactory.getLog(SolrQueryService.class);
         private CloudSolrServer solrServer;
         private static final String writerType = "json";
         
         public SolrQueryService(Configurable context) {
              super(context);
              String zkHost = context.get("query.proxy.solr.zkHost");
              try {
                   solrServer = new CloudSolrServer(zkHost);
              } catch (MalformedURLException e) {
                   throw new RuntimeException(e);
              }
         }
         
         @Override
         public QueryResult query(QueryParams params) throws QueryFailureException, TException {
              int offset = 0;
              int length = 10;
              Map<String,String> map = new HashMap<>();
              Iterator<String> iter = params.getParamListIterator();
              while(iter.hasNext()) {
                   String kv = iter.next();
                   if(kv != null) {
                        String[] items = kv.split("=");
                        if(items.length == 2) {
                             String key = items[0].trim();
                             String value = items[1].trim();
                             map.put(key, value);
                             if(key.equals(CommonParams.START)) {
                                  offset = Integer.parseInt(value);
                             }
                             if(key.equals(CommonParams.ROWS)) {
                                  length = Integer.parseInt(value);
                             }
                        }
                   }
              }
              map.put("collection", params.getTable());
              map.put("wt", writerType);
              LOG.info("Solr params: " + map);
              
              // query using Solr
              QueryResponse response = null;
              SolrParams solrParams = new MapSolrParams(map);
              try {
                   response = solrServer.query(solrParams);
              } catch (SolrServerException e) {
                   LOG.error("Failed to query solr server: ", e);
                   throw new QueryFailureException(e.toString());
              }
              
              // process result
              QueryResult result = new QueryResult();
              result.setOffset(offset);
              result.setLength(length);
              if(response != null) {
                   result.setResults(ResultUtils.getJSONResults(response));
              }
              return result;
         }
    
         @Override
         public void close() throws IOException {
              solrServer.shutdown();     
         }
         
    }

为简单起见，上面只是使用了一个CloudSolrServer客户端来连接Solr服务器集群（通过ZooKeeper集群）。在query方法中，首先解析查询参数数据，然后构建成Solr查询支持的参数格式，提交到Solr查询服务器集群，然后等待返回结果QueryResponse ，接着从返回的QueryResponse对象中提取查询命中的结果文档集合，然后转换成Thrift服务定义中满足的返回结果对象形式，通过下面的累ResultUtils类来实现转换操作，getJSONResults(response)实现如下所示：

private static final String KEY_VERSION = "_version_";
         private static final DateFormat DF = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
         
         public static List<String> getJSONResults(QueryResponse response) {
              ListIterator<SolrDocument> iter = response.getResults().listIterator();
              List<String> resultDocs = new ArrayList<String>();
              while(iter.hasNext()) {
                   SolrDocument doc = iter.next();
                   JSONObject jDoc = new JSONObject();
                   Set<String> ks = doc.keySet();
                   if(ks.contains(KEY_VERSION)) {
                        ks.remove(KEY_VERSION);
                   }
                   for(String key : ks) {
                        Object v = doc.getFieldValue(key);
                        if(v instanceof Date) {
                             jDoc.put(key, DF.format((Date) v));
                             continue;
                        }
                        jDoc.put(key, v);
                   }
                   resultDocs.add(jDoc.toString());
              }
              return resultDocs;
         }

一条结果，构建一个JSON对象，返回一个JSON对象列表。这样，Solr查询服务的Thrift服务就实现了。

*  SQL查询服务

基于关系数据库的SQL查询就比较容易了，我们简单地使用JDBC来直接进行。我们基于MysQL数据库，实现SQL查询的JDBC配置文件内容，如下所示：

jdbc.jdbcUrl=jdbc:mysql://localhost:3306/wordpress?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&transformedBitIsBoolean=true
    jdbc.driverClass=com.mysql.jdbc.Driver
    jdbc.user=shirdrn
    jdbc.password=shiyanjun

Thrift查询服务实现类为SQLQueryService，实现代码，如下所示：

package org.shirdrn.queryproxy.thrift.service.sql;
    
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.thrift.TException;
    import org.shirdrn.queryproxy.common.Configurable;
    import org.shirdrn.queryproxy.common.ConfiguredQueryService;
    import org.shirdrn.queryproxy.thrift.protocol.QueryFailureException;
    import org.shirdrn.queryproxy.thrift.protocol.QueryParams;
    import org.shirdrn.queryproxy.thrift.protocol.QueryResult;
    import org.shirdrn.queryproxy.utils.PropertiesConfig;
    import org.shirdrn.queryproxy.utils.ResultUtils;
    
    public class SQLQueryService extends ConfiguredQueryService {
    
         private static final Log LOG = LogFactory.getLog(SQLQueryService.class);
         private static String JDBC_PROPERTIES = "jdbc.properties";
         Configurable jdbcConf;
         private String jdbcUrl;
         private String user;
         private String password;
         Connection connection;
         
         public SQLQueryService(Configurable context) {
              super(context);
              jdbcConf = new PropertiesConfig(JDBC_PROPERTIES);
              String driverClass = jdbcConf.get("jdbc.driverClass");
              try {
                   Class.forName(driverClass);
                   jdbcUrl = jdbcConf.get("jdbc.jdbcUrl");
                   user = jdbcConf.get("jdbc.user");
                   password = jdbcConf.get("jdbc.password");
              } catch (ClassNotFoundException e) {
                   throw new RuntimeException(e);
              } finally {
                   LOG.info("JDBC: driver=" + driverClass + ", url=" + jdbcUrl + ", user=" + user + ", password=******");
              }
         }
    
         @Override
         public QueryResult query(QueryParams params) throws QueryFailureException, TException {
              QueryResult result = new QueryResult();
              if(!params.getParamList().isEmpty()) {
                   // get SQL statement
                   String sql = params.getParamList().remove(0);
                   Connection conn = getConnection();
                   Statement stmt = null;
                   ResultSet rs = null;
                   try {
                        stmt = conn.createStatement();
                        rs = stmt.executeQuery(sql);
                        result.setResults(ResultUtils.getJSONResults(rs, params.getParamList()));
                   } catch (SQLException e) {
                        throw new QueryFailureException(e.toString());
                   }
              }
              return result;
         }
         
         private synchronized final Connection getConnection() {
              try {
                   if(connection == null || connection.isClosed()) {
                        if(user != null) {
                             connection = DriverManager.getConnection(jdbcUrl, user, password);
                        } else {
                             connection = DriverManager.getConnection(jdbcUrl);
                        }
                   }
              } catch (SQLException e) {
                   e.printStackTrace();
              }
              return connection;
         }
    
         @Override
         public void close() throws IOException {
              if(connection != null) {
                   try {
                        connection.close();
                   } catch (SQLException e) {
                        throw new IOException(e);
                   }
              }
         }
    }

上面也使用了ResultUtils类实现了结果的转换方法，实现如下所示：

public static List<String> getJSONResults(ResultSet rs, List<String> fields) throws SQLException {
              List<String> results = new ArrayList<String>();
              while(rs.next()) {
                   JSONObject jo = new JSONObject();
                   for(String field : fields) {
                        jo.put(field, rs.getObject(field).toString());
                   }
                   results.add(jo.toString());
              }
              return results;
         }

返回一组JSON对象，客户端只需要单个解析每一个对象即可。这样基于SQL的Thrift服务也实现完成了。

上面的两类服务都已经实现了，我们最终还要组合成一个服务，然后通过Thrift协议暴露给外部。组合服务的实现类同样实现了org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Iface接口，实现代码如下所示：

package org.shirdrn.queryproxy;
    
    import java.io.Closeable;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.Map;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.thrift.TException;
    import org.shirdrn.queryproxy.common.Configurable;
    import org.shirdrn.queryproxy.thrift.protocol.QueryFailureException;
    import org.shirdrn.queryproxy.thrift.protocol.QueryParams;
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Iface;
    import org.shirdrn.queryproxy.thrift.protocol.QueryResult;
    import org.shirdrn.queryproxy.thrift.protocol.QueryType;
    import org.shirdrn.queryproxy.utils.ReflectionUtils;
    
    public class ThriftQueryService implements Iface {
    
         private static final Log LOG = LogFactory.getLog(ThriftQueryService.class);
         private Configurable context;
         static Map<QueryType, Iface> SERVICES = new HashMap<QueryType, Iface>(0);
         static {
              Runtime.getRuntime().addShutdownHook(new Thread() {
                   @Override
                   public void run() {
                        for(Map.Entry<QueryType, Iface> entry : SERVICES.entrySet()) {
                             try {
                                  ((Closeable) entry.getValue()).close();
                             } catch (IOException e) {
                                  e.printStackTrace();
                             } finally {
                                  LOG.info("Closed: type=" + entry.getKey() + ", service=" + entry.getValue());
                             }
                        }
                   }
              });
         }
         
         @Override
         public QueryResult query(QueryParams params) throws QueryFailureException, TException {
              int type = params.getType().getValue();
              Iface service = SERVICES.get(QueryType.findByValue(type));
              if(service == null) {
                   throw new QueryFailureException("Unknown service: type=" + params.getType().name());
              }
              return service.query(params);
         }
    
         public void register(QueryType queryType, Class<?> serviceClass) {
              Iface service = (Iface) ReflectionUtils.getInstance(serviceClass, new Object[] {context});
              SERVICES.put(queryType, service);
         }
         
         public void setContext(Configurable context) {
              this.context = context;
         }
    }

上面实现，就是通过一个注册方法，将前面实现的两类服务注册管理起来。   
下面，我们看一下，基于Thrift的库将组合后的服务以Thrift协议暴露给外部，实际上就是单独启动了一个Thrift服务（关联一个端口），实现的Thrift服务器代码，如下所示：

package org.shirdrn.queryproxy;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.thrift.TProcessor;
    import org.apache.thrift.protocol.TBinaryProtocol;
    import org.apache.thrift.protocol.TBinaryProtocol.Factory;
    import org.apache.thrift.server.TServer;
    import org.apache.thrift.server.TThreadPoolServer;
    import org.apache.thrift.server.TThreadPoolServer.Args;
    import org.apache.thrift.transport.TServerSocket;
    import org.apache.thrift.transport.TTransportException;
    import org.shirdrn.queryproxy.common.Configurable;
    import org.shirdrn.queryproxy.thrift.protocol.QueryType;
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Iface;
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService.Processor;
    import org.shirdrn.queryproxy.thrift.service.solr.SolrQueryService;
    import org.shirdrn.queryproxy.thrift.service.sql.SQLQueryService;
    import org.shirdrn.queryproxy.utils.PropertiesConfig;
    
    public class QueryProxyServer {
    
         private static final Log LOG = LogFactory.getLog(QueryProxyServer.class);
         static final String config = "config.properties";
         private final Configurable context;
         
         public QueryProxyServer() {
              super();
              context = loadContext();
         }
         
         private Configurable loadContext() {
              return new PropertiesConfig(config);
         }
         
         public void startUp() throws TTransportException {
              int port = context.getInt("query.proxy.thrift.port", 9966);
              LOG.info("Thrift service port: port=" + port);
              TServerSocket serverTransport = new TServerSocket(port);
              
              ThriftQueryService service = new ThriftQueryService();
              service.setContext(context);
              service.register(QueryType.SOLR, SolrQueryService.class);
              service.register(QueryType.SQL, SQLQueryService.class);
              
              int minWorkerThreads = context.getInt("query.proxy.thrift.worker.thread.minCount", 1);
              int maxWorkerThreads = context.getInt("query.proxy.thrift.worker.thread.maxCount", 1);
              LOG.info("Thrift thread pool: minWorkerThreads=" + minWorkerThreads + ", maxWorkerThreads=" + maxWorkerThreads);
              
              TProcessor processor = new Processor<Iface>(service);
              Factory factory = new TBinaryProtocol.Factory(true, true);
              Args tArgs = new Args(serverTransport);
              tArgs
                   .minWorkerThreads(minWorkerThreads)
                   .maxWorkerThreads(maxWorkerThreads)
                   .processor(processor)
                   .protocolFactory(factory);
              TServer server = new TThreadPoolServer(tArgs);
              server.serve();
         }
         
         public static void main(String[] args) throws Exception {
              QueryProxyServer server = new QueryProxyServer();
              server.startUp();
         }
    
    }

启动该服务以后，外部客户端连接我们配置的9966端口，就可以进行查询调用。

Thrift服务调用

Thrift服务已经发布，我们可以基于Thrift协议进行调用，这里基于Java和C\#语言来实现客户端查询调用。

*  Java查询客户端实现

我们以测试用例的形式展示客户端如何调用。   
查询关系数据的SQL调用，客户端实现代码如下所示：

package org.shirdrn.queryproxy.thrift.service.sql;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.thrift.TException;
    import org.apache.thrift.protocol.TBinaryProtocol;
    import org.apache.thrift.protocol.TProtocol;
    import org.apache.thrift.transport.TSocket;
    import org.apache.thrift.transport.TTransport;
    import org.junit.Test;
    import org.shirdrn.queryproxy.thrift.protocol.QueryFailureException;
    import org.shirdrn.queryproxy.thrift.protocol.QueryParams;
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService;
    import org.shirdrn.queryproxy.thrift.protocol.QueryResult;
    import org.shirdrn.queryproxy.thrift.protocol.QueryType;
    
    public class TestSQLQueryService {
    
    private static final Log LOG = LogFactory.getLog(TestSQLQueryService.class);
         
         @Test
         public void query() throws QueryFailureException, TException {
              String host = "server.query-proxy.local";
              TTransport transport = new TSocket(host, 9966);
              TProtocol protocol = new TBinaryProtocol(transport, true, true);
              transport.open();
              QueryProxyService.Client client = new QueryProxyService.Client(protocol);
              
              QueryParams params = new QueryParams();
              params.setTable("wp_posts");
              params.setType(QueryType.SQL);
              params.addToParamList("select id, post_author from wordpress.wp_posts");
              params.addToParamList("id");
              params.addToParamList("post_author");
              
              QueryResult result = client.query(params);
              LOG.info("result=" + result.getResults());
              transport.close();
         }
    }

运行结果输出，大概如下格式：

result=[{
      "id":"1","post_author":"2"}, {
      "id":"4","post_author":"2"}, {
      "id":"57","post_author":"2"}, {
      "id":"66","post_author":"2"}, {
      "id":"72","post_author":"2"}, {
      "id":"75","post_author":"2"}, {
      "id":"78","post_author":"2"}, {
      "id":"94","post_author":"2"}, {
      "id":"100","post_author":"2"}, {
      "id":"107","post_author":"2"}]

查询Solr服务器的调用，客户端实现代码如下所示：

package org.shirdrn.queryproxy.thrift.service.solr;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.thrift.TException;
    import org.apache.thrift.protocol.TBinaryProtocol;
    import org.apache.thrift.protocol.TProtocol;
    import org.apache.thrift.transport.TSocket;
    import org.apache.thrift.transport.TTransport;
    import org.junit.Test;
    import org.shirdrn.queryproxy.thrift.protocol.QueryFailureException;
    import org.shirdrn.queryproxy.thrift.protocol.QueryParams;
    import org.shirdrn.queryproxy.thrift.protocol.QueryProxyService;
    import org.shirdrn.queryproxy.thrift.protocol.QueryResult;
    import org.shirdrn.queryproxy.thrift.protocol.QueryType;
    
    public class TestSolrQueryProxy {
    
         private static final Log LOG = LogFactory.getLog(TestSolrQueryProxy.class);
         
         @Test
         public void query() throws QueryFailureException, TException {
              String host = "server.query-proxy.local";
              TTransport transport = new TSocket(host, 9966);
              TProtocol protocol = new TBinaryProtocol(transport, true, true);
              transport.open();
              QueryProxyService.Client client = new QueryProxyService.Client(protocol);
              
              QueryParams params = new QueryParams();
              params.setTable("collection1");
              params.setType(QueryType.SOLR);
              params.addToParamList("q=上海");
              params.addToParamList("fl=*");
              params.addToParamList("fq=building_type:1");
              params.addToParamList("start=50");
              params.addToParamList("rows=10");
              params.addToParamList("wt=json");
              
              QueryResult result = client.query(params);
              LOG.info("offset=" + result.getOffset());
              LOG.info("length=" + result.getLength());
              LOG.info("result=" + result.getResults());
              transport.close();
         }
         
    }

调用Thrift服务查询结果输出，大概如下格式：

result=[{
      "area":"上海","building_type":1,"floor":28,"category":"住宅","temperature":18,"code":576546387,"latitude":63.054478,"longitude":77.491035,"when":"2013-10-15 02:21:12","id":"0ca9ff70-6b33-42fd-a4e1-23a534b739f5"}, {
      "area":"上海","building_type":1,"floor":45,"category":"办公建筑","temperature":-71,"code":824153427,"latitude":6.464198,"longitude":14.567751,"when":"2013-10-15 02:21:20","id":"25f46be0-f875-48b7-9f33-077602b2e820"}, {
      "area":"上海","building_type":1,"floor":21,"category":"工业建筑","temperature":16,"code":215543388,"latitude":66.565796,"longitude":34.4735,"when":"2013-10-15 02:21:36","id":"0b32cd10-ea40-4cdc-b23b-c6edccd7505d"}, {
      "area":"上海","building_type":1,"floor":53,"category":"工业建筑","temperature":-23,"code":435344533,"latitude":24.783417,"longitude":119.01849,"when":"2013-10-15 02:21:37","id":"f324b65d-f3be-485a-9ed1-2f12a70b5d87"}, {
      "area":"上海","building_type":1,"floor":78,"category":"教育建筑","temperature":-76,"code":298014795,"latitude":9.153033,"longitude":8.273011,"when":"2013-10-15 02:21:39","id":"7a9ea8d8-fad1-4c0b-bdb4-09851eee1432"}, {
      "area":"上海","building_type":1,"floor":35,"category":"办公建筑","temperature":-3,"code":228287827,"latitude":13.038927,"longitude":62.056316,"when":"2013-10-15 02:21:42","id":"d6ed8172-a5e6-4391-b039-3b4465eabe9b"}, {
      "area":"上海","building_type":1,"floor":77,"category":"公寓","temperature":28,"code":942108396,"latitude":61.970222,"longitude":4.418831,"when":"2013-10-15 02:21:42","id":"85a76085-90e9-4f62-b10c-5a4895a4d08b"}, {
      "area":"上海","building_type":1,"floor":40,"category":"办公建筑","temperature":50,"code":175416908,"latitude":38.17303,"longitude":148.83298,"when":"2013-10-15 02:21:51","id":"1496f73b-8057-4c7b-8ba9-bff4a4ee5189"}, {
      "area":"上海","building_type":1,"floor":32,"category":"办公建筑","temperature":-52,"code":299718959,"latitude":30.68149,"longitude":54.327663,"when":"2013-10-15 02:22:05","id":"216a0b93-4872-45aa-baec-2f11e128f76e"}, {
      "area":"上海","building_type":1,"floor":78,"category":"住宅","temperature":5,"code":586785207,"latitude":36.27908,"longitude":143.60094,"when":"2013-10-15 02:22:06","id":"10065088-02bf-422e-8761-54635668e1fe"}]

*  C\#查询客户端实现

使用C\#实现查询服务的调用，首先从Thrift发行包的thrift-0.9.1\\lib\\csharp目录下C\#相关的Thrift库文件导入到开发环境，然后还要将Thrift编译器编译生成的C\#代码也加入到开发环境，然后就可以实现客户端调用查询的代码，我们实现的如下所示：

using System;
    using System.Collections.Generic;
    
    using Thrift.Transport;
    using Thrift.Protocol;
    using Query.Proxy.Thrift.Protocol;
    
    namespace CSharpQueryClient
    {
        class QueryClient
        {
            static void Main(string[] args)
            {
                string host = "server.query-proxy.local";
                TTransport transport = new TSocket(host, 9966);
                TProtocol protocol = new TBinaryProtocol(transport, true, true);
                transport.Open();
                QueryProxyService.Client client = new QueryProxyService.Client(protocol);
    
                QueryParams queryParams = new QueryParams();
                queryParams.Table = "collection1";
                queryParams.Type = QueryType.SOLR;
                queryParams.ParamList = new List<string>();
                queryParams.ParamList.Add("q=上海");
                queryParams.ParamList.Add("fl=*");
                queryParams.ParamList.Add("fq=building_type:1");
                queryParams.ParamList.Add("start=50");
                queryParams.ParamList.Add("rows=10");
                queryParams.ParamList.Add("wt=json");
    
                QueryResult result = client.query(queryParams);
                Console.WriteLine("offset=" + result.Offset);
                Console.WriteLine("length=" + result.Length);
                foreach (string record in result.Results)
                {
                    Console.WriteLine("record=" + record);
                }
                
                Console.Read();
            }
        }
    }

执行结果，与前面Java客户端的结果一致。