Flink-SQL Windowed-Table联接？

Question

由于限制，我只能使用Flink v 1.4.2。我正在研究窗口联接。

CustomObj.java（POJO）

class CustomObj{
   public long timestampVal; 
   public int value;
}

我有2个数据流，例如：

StreamExecutionEnvironment currentEnv = getEnv();
currentEnv.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
StreamTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(currentEnv); TableEnvironment.getTableEnvironment(currentEnv);
DataStream<CustomObj> s1 = ...assignTimeStampsAndWatermarks(...)...
DataStream<CustomObj> s2 = ...assignTimeStampsAndWatermarks(...)...

tableEnv.registerDataStream("s1", s1);
tableEnv.registerDataStream("s2", s2);

我想做：

SELECT * FROM s1 INNER JOIN s2 ON s1.timestampVal = s2.timestampVal

但是，INNER JOIN中不支持Flink V 1.4.2进行流传输，因此我想知道是否可以进行某种TimeWindow连接？究竟如何运作？