multiple engines on single database - tenant question

btomas — Wed, 04 Nov 2015 16:39:04 GMT

Activiti engine A and engine B (v.5.17) are running on single database. To distinguish data content per engine tenancy is used - A has tenantId=tenant_A and B has tenantId=tenant_B. The situation similar to Shared Database Multi-tenancy but here i've got separate applications running Activiti en

Re: multiple engines on single database - tenant question

martin_grofcik — Thu, 05 Nov 2015 10:31:13 GMT

Hi,

* how tenancy could be applied when acquiring for async jobs?

Multitenancy was not meant to distinguish between nodes (A,B). You can implement your own job executor.

The second question -> I do not have any good proposal.

Regards
Martin

Re: multiple engines on single database - tenant question

btomas — Fri, 06 Nov 2015 14:38:15 GMT

It doesn't look that i need providing my own JobExecutor to make different Activiti engine apps to poll their own jobs by tenantId.
There were some threads already started regarding "multiple engines - single database" (Could multiple Activiti engines share one Repository?, Usage of more than one Activiti Engines on one database ) but i didn't find particular answer to my question.
I'll describe how i made polling jobs by tenantId per multiple Activiti engines running on single DB:

1. Provide custom engine configuration
<code>
public class CustomSpringProcessEngineConfiguration extends SpringProcessEngineConfiguration {

 public static final String CUSTOM_MYBATIS_MAPPING_FILE = "com/custom/activiti/query/custom-mappings.xml";

 @Override
 protected InputStream getMyBatisXmlConfigurationSteam() {
 return ReflectUtil.getResourceAsStream(CUSTOM_MYBATIS_MAPPING_FILE);
 }
}
</code>

The custom-mappings.xml actually is a copy of Activiti mappings.xml with my customizations and overriding the Activiti Job.xml implementation.

2. Create my custom job entity manager
<code>
import org.activiti.engine.impl.interceptor.Session;
import org.activiti.engine.impl.interceptor.SessionFactory;
import org.activiti.engine.impl.persistence.entity.JobEntityManager;

public class CustomJobEntityManagerFactory implements SessionFactory {

@Override
public Class<?> getSessionType() {
return JobEntityManager.class;
}

@Override
public Session openSession() {
return new CustomJobEntityManager();
}
}
</code>

provide the implementation for the custom job entity manager:
<code>
public class CustomJobEntityManager extends JobEntityManager {

@Override
public List<JobEntity> findNextJobsToExecute(Page page) {
 ProcessEngineConfiguration processEngineConfig = Context.getProcessEngineConfiguration();
 Map<String, Object> parameter = Maps.newHashMap();
 Date now = processEngineConfig.getClock().getCurrentTime();
 parameter.put("tenantId", retrieveCustomTenantId());
 parameter.put("dueDate", now);
 return getDbSqlSession().selectList("selectNextJobsToExecute", parameter, page);
}

// TODO override other queries by duedate …
}
</code>

3. Add custom job entity manager to custom session list in Spring process engine configuration based on my CustomSpringProcessEngineConfiguration with overriden getMyBatisXmlConfigurationSteam
<code>
<bean id="customPocessEngineConfiguration" class="com.custom.activiti.engine.CustomSpringProcessEngineConfiguration">
 <property name="dataSource" ref="dataSource" />
 <property name="transactionManager" ref="transactionManager" />
 <property name="customSessionFactories">
….
….
….
 <list>
 <ref bean="activitiCustomJobEntiyManagerFactory"/>
 </list>
 </property>

<bean id="activitiCustomJobEntiyManagerFactory" class="com.custom.activiti.job.CustomJobEntityManagerFactory"/>
</code>

4. create a mirror of Activiti Job.xml -> CustomJob.xml with same queries appended with tenantId in WHERE clause and include it in my com/custom/activiti/query/custom-mappings.xml specified in my overriden process engine configuration CustomSpringProcessEngineConfiguration :
<code>
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.activiti.engine.impl.persistence.entity.JobEntity">

….
….

<select id="selectNextJobsToExecute" parameterType="org.activiti.engine.impl.db.ListQueryParameterObject" resultMap="jobResultMap">
 ${limitBefore}
 select
 RES.* ${limitBetween}
 from ${prefix}ACT_RU_JOB RES
 LEFT OUTER JOIN ${prefix}ACT_RU_EXECUTION PI ON PI.ID_ = RES.PROCESS_INSTANCE_ID_
 where (RES.RETRIES_ > 0)
 and (RES.DUEDATE_ is null or RES.DUEDATE_ <= #{parameter.dueDate, jdbcType=TIMESTAMP})
 and (RES.LOCK_OWNER_ is null or RES.LOCK_EXP_TIME_ <= #{parameter.dueDate, jdbcType=TIMESTAMP})
 and (
 (RES.EXECUTION_ID_ is null)
 or
 (PI.SUSPENSION_STATE_ = 1)
 )
 <include refid="tenantIdCriteria"/>
 ${limitAfter}
</select>

<sql id="tenantIdCriteria">
<if test="parameter.tenantId != null">
 and RES.TENANT_ID_ = #{parameter.tenantId}
</if>
</sql>

….
….

</code>

Thats it.

Couldn't get to a cleaner solution at the moment. What i don't like here - i keep a copy of mappings.xml and override Job.xml. Such implementation complicates upgrading to new Activiti versions and it may introduce new bugs.

Questions:

The ACT_RU_JOB contains TENANT_ID_ and it is filled when job created. Why tenantId is not used in job polling? Maybe there are some threats for which polling by tenantId was not introduced?
org.activiti.engine.impl.persistence.entity.JobEntityManager works with the default job executor. If i want the new async job executor to use tenantId - would it be enough to override org.activiti.engine.impl.persistence.entity.data.impl.MybatisJobDataManager the same way as the JobEntityManager?
Is there any other solution to make polling jobs by tenantId without copying Job.xml as described above?
Would JobEntityManager/MybatisJobDataManager cover all job executions polling that occur in BPMN asynchronously (timers, parallel gateway, async…)?

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multiple engines on single database - tenant question

Re: multiple engines on single database - tenant question

Re: multiple engines on single database - tenant question