运行接下来几节中的示例的软件要求如下：

第 5.2 节“安装 JavaScript 连接器”描述了所有这三个要求的安装过程。

示例数据库、表和数据。  所有示例都使用数据库中名为 tweet,的示例表test 。此表在以下 CREATE TABLE语句中定义：

CREATE TABLE IF NOT EXISTS tweet  (
    id CHAR(36) NOT NULL PRIMARY KEY,
    author VARCHAR(20),
    message VARCHAR(140),
    date_created TIMESTAMP,

    KEY idx_btree_date_created (date_created),
    KEY idx_btree_author(author)
)
ENGINE=NDB;

可以通过在 mysqltweet客户端中运行包含的 SQL 脚本来创建 该表。您可以通过在系统 shell 中调用 mysql来完成此操作，如下所示： create.sql

$> mysql < create.sql

所有示例还使用了文件中定义的两个模块lib.js，其内容在此处复制：

# FILE: lib.js

"use strict";

var udebug = unified_debug.getLogger("samples/lib.js");
var exec = require("child_process").exec;
var SQL = {};

/* Pseudo random UUID generator */

var randomUUID = function() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
    return v.toString(16);
    });
};

/* Tweet domain object model */

var Tweet = function(author, message) {
  this.id = randomUUID();
  this.date_created = new Date();
  this.author = author;
  this.message = message;
};

/* SQL DDL Utilities */

var runSQL = function(sqlPath, source, callback) {

  function childProcess(error, stdout, stderr) {
    udebug.log('harness runSQL process completed.');
    udebug.log(source + ' stdout: ' + stdout);
    udebug.log(source + ' stderr: ' + stderr);
    if (error !== null) {
      console.log(source + 'exec error: ' + error);
    } else {
      udebug.log(source + ' exec OK');
    }
    if(callback) {
      callback(error);
    }
  }

  var p = mysql_conn_properties;
  var cmd = 'mysql';
  if(p) {
    if(p.mysql_socket)     { cmd += " --socket=" + p.mysql_socket; }
    else if(p.mysql_port)  { cmd += " --port=" + p.mysql_port; }
    if(p.mysql_host)     { cmd += " -h " + p.mysql_host; }
    if(p.mysql_user)     { cmd += " -u " + p.mysql_user; }
    if(p.mysql_password) { cmd += " --password=" + p.mysql_password; }
  }
  cmd += ' <' + sqlPath;
  udebug.log('harness runSQL forking process...');
  var child = exec(cmd, childProcess);
};

SQL.create =  function(suite, callback) {
  var sqlPath = path.join(suite.path, 'create.sql');
  udebug.log_detail("createSQL path: " + sqlPath);
  runSQL(sqlPath, 'createSQL', callback);
};

SQL.drop = function(suite, callback) {
  var sqlPath = path.join(suite.path, 'drop.sql');
  udebug.log_detail("dropSQL path: " + sqlPath);
  runSQL(sqlPath, 'dropSQL', callback);
};


/* Exports from this module */
exports.SQL               = SQL;
exports.Tweet             = Tweet;

最后，文件中包含一个用于随机数据生成的模块ndb_loader/lib/RandomData.js，如下所示：

# FILE: RandomData.js

var assert = require("assert");


function RandomIntGenerator(min, max) {
  assert(max > min);
  var range = max - min;
  this.next = function() {
    var x = Math.floor(Math.random() * range);
    return min + x;
  };
}


function SequentialIntGenerator(startSeq) {
  var seq = startSeq - 1;
  this.next = function() {
    seq += 1;
    return seq;
  };
}


function RandomFloatGenerator(min, max, prec, scale) {
  assert(max > min);
  this.next = function() {
    var x = Math.random();
    /* fixme! */
    return 100 * x;
  };
}


function RandomCharacterGenerator() {
  var intGenerator = new RandomIntGenerator(32, 126);
  this.next = function() {
    return String.fromCharCode(intGenerator.next());
  };
}


function RandomVarcharGenerator(length) {
  var lengthGenerator = new RandomIntGenerator(0, length),
      characterGenerator = new RandomCharacterGenerator();
  this.next = function() {
    var i = 0,
        str = "",
        len = lengthGenerator.next();
    for(; i < len ; i++) str += characterGenerator.next();
    return str;
  }
}


function RandomCharGenerator(length) {
  var characterGenerator = new RandomCharacterGenerator();
  this.next = function() {
    var i = 0,
        str = "";
    for(; i < length ; i++) str += characterGenerator.next();
    return str;
  };
}


function RandomDateGenerator() {
  var generator = new RandomIntGenerator(0, Date.now());
  this.next = function() {
    return new Date(generator.next());
  };
}


function RandomGeneratorForColumn(column) {
  var g = {},
      min, max, bits;

  switch(column.columnType.toLocaleUpperCase()) {
    case "TINYINT":
    case "SMALLINT":
    case "MEDIUMINT":
    case "INT":
    case "BIGINT":
      if(column.isInPrimaryKey) {
        g = new SequentialIntGenerator(0);
      }
      else {
        bits = column.intSize * 8;
        max = column.isUnsigned ? Math.pow(2,bits)-1 : Math.pow(2, bits-1);
        min = column.isUnsigned ?                  0 : 1 - max;
        g = new RandomIntGenerator(min, max);
      }
      break;
    case "FLOAT":
    case "DOUBLE":
    case "DECIMAL":
      g = new RandomFloatGenerator(0, 100000); // fixme
      break;
    case "CHAR":
      g = new RandomCharGenerator(column.length);
      break;
    case "VARCHAR":
      g = new RandomVarcharGenerator(column.length);
      break;
    case "TIMESTAMP":
      g = new RandomIntGenerator(0, Math.pow(2,32)-1);
      break;
    case "YEAR":
      g = new RandomIntGenerator(1900, 2155);
      break;
    case "DATE":
    case "TIME":
    case "DATETIME":
      g = new RandomDateGenerator();
      break;
    case "BLOB":
    case "TEXT":
    case "BIT":
    case "BINARY":
    case "VARBINARY":
    default:
      throw("UNSUPPORTED COLUMN TYPE " + column.columnType);
      break;
  }

  return g;
}


function RandomRowGenerator(table) {
  var i = 0,
      generators = [];
  for(; i < table.columns.length ; i++) {
    generators[i] = RandomGeneratorForColumn(table.columns[i]);
  }

  this.newRow = function() {
    var n, col, row = {};
    for(n = 0; n < table.columns.length ; n++) {
      col = table.columns[n];
      row[col.name] = generators[n].next();
    }
    return row;
  };
}

exports.RandomRowGenerator = RandomRowGenerator;
exports.RandomGeneratorForColumn = RandomGeneratorForColumn;