Custom Variable Design

1. Support variable substitution of task code

2. During the execution of the Linkis task, the custom variables are carried out in Entrance, mainly through the interceptor of Entrance before the task is submitted and executed. The variable and the defined variable, and complete the code replacement through the initial value of the custom variable passed in by the task, and become the final executable code.

   The overall structure of custom variables is as follows. After the task is submitted, it will go through the variable replacement interceptor. First, all variables and expressions used in the code will be parsed, and then replaced with the system and user-defined initial values ​​of variables, and finally the parsed code will be submitted to EngineConn for execution. So the underlying engine is already replaced code.

The currently supported built-in variables are as follows:

details:

1. Definition of other derived built-in date variables: other date built-in variables are calculated relative to run_date. Once run_date changes, other variable values ​​will also change automatically. Other date variables do not support setting initial values ​​and can only be modified by modifying run_date. .

The use is directly used in the code through