爲什麼不是best practice? 只是想記下一些別人沒做好做對的地方.
1. 濫用/abuse ContextInstance.setVariable(String name, Object value)
CREATE TABLE `jbpm_variableinstance` (
`ID_` bigint(20) NOT NULL auto_increment,
`CLASS_` char(1) NOT NULL,
`NAME_` varchar(255) default NULL,
`CONVERTER_` char(1) default NULL,
`TOKEN_` bigint(20) default NULL,
`TOKENVARIABLEMAP_` bigint(20) default NULL,
`PROCESSINSTANCE_` bigint(20) default NULL,
`BYTEARRAYVALUE_` bigint(20) default NULL,
`DATEVALUE_` datetime default NULL,
`DOUBLEVALUE_` double default NULL,
`LONGIDCLASS_` varchar(255) default NULL,
`LONGVALUE_` bigint(20) default NULL,
`STRINGIDCLASS_` varchar(255) default NULL,
`STRINGVALUE_` text,
`TASKINSTANCE_` bigint(20) default NULL,
PRIMARY KEY (`ID_`),
KEY `FK_VARINST_TK` (`TOKEN_`),
KEY `FK_VARINST_TKVARMP` (`TOKENVARIABLEMAP_`),
KEY `FK_VARINST_PRCINST` (`PROCESSINSTANCE_`),
KEY `FK_VAR_TSKINST` (`TASKINSTANCE_`),
KEY `FK_BYTEINST_ARRAY` (`BYTEARRAYVALUE_`),
CONSTRAINT `FK_BYTEINST_ARRAY` FOREIGN KEY (`BYTEARRAYVALUE_`) REFERENCES `jbpm_bytearray` (`ID_`),
CONSTRAINT `FK_VARINST_PRCINST` FOREIGN KEY (`PROCESSINSTANCE_`) REFERENCES `jbpm_processinstance` (`ID_`),
CONSTRAINT `FK_VARINST_TK` FOREIGN KEY (`TOKEN_`) REFERENCES `jbpm_token` (`ID_`),
CONSTRAINT `FK_VARINST_TKVARMP` FOREIGN KEY (`TOKENVARIABLEMAP_`) REFERENCES `jbpm_tokenvariablemap` (`ID_`),
CONSTRAINT `FK_VAR_TSKINST` FOREIGN KEY (`TASKINSTANCE_`) REFERENCES `jbpm_taskinstance` (`ID_`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
我們可以看到對於date,long,double,string 類型我們直接是可以保存到variableinstance表的, 如果是串行化的對象就麻煩了.
jbpm_variableinstance.bytearrayvalue_ => jbpm_bytearray.id_ => jbpm_byteblock.processfile_,bytes_,index_.
jbpm_bytearray表只有id有用其餘兩列空, 更鬱悶的是串行化的對象放在jbpm_byteblock還分段保存, 用index_作爲分段的下標.
經驗是別輕易使用ContextInstance.setVariable()保存一些對象, 串行化對象關聯表太多啦;
ContextInstance.deleteVariable(String name)只能刪除jbpm_variableinstance的列, bytearray/byteblock刪不了的;
而且你更新的時候更要命, 調用ContextInstance.setVariable()再次更新的時候, jbpm_variableinstance相應列是更新了, 只是會創建新的bytearray/byteblock, 之前舊的byteblock一直留在數據庫沒外部引用了, 你使用JBPM API delete processinstance也找不到來刪了.
所以儘量使用原生的long,double,string,date等值傳到工作流裏面, 沒必要保存到數據庫的臨時變量又是在同一線程操作的話使用ContextInstance.setTransientVariable; 否則jbpm的數據庫很容易膨脹。
(To be continued)