Camunda History Stream For Human Task Activities

This project illustrates usage of Camunda "alternative" data store for managing Human Tasks outside of Camunda Core tables. The functionality doesn't remove the core features for saving data to historical tables just extends history events and store data additionally into custom tables. Those data can be used for reporting or showing task activities on custom dashboards etc.

Project use Spring Boot and embedded Camunda Engine and MySQL database.

Database table

For creating a database, you can use the query bellow or schema.sql file in root of the project.

CREATE DATABASE IF NOT EXISTS `cam-history` CHARSET utf8 COLLATE utf8_slovenian_ci;

CREATE TABLE `cam-history`.`task_event` (
  `id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
  `process_definition_key` VARCHAR(255) NOT NULL,
  `process_definition_name` VARCHAR(255) NOT NULL,
  `process_instance_id` VARCHAR(255) NOT NULL,
  `super_process_instance_id` VARCHAR(255) NULL DEFAULT NULL,
  `execution_id` VARCHAR(255) NOT NULL,
  `task_instance_id` VARCHAR(255) NOT NULL,
  `task_id` VARCHAR(255) NOT NULL,
  `task_name` VARCHAR(255) NOT NULL,
  `last_assignee` VARCHAR(255) NULL DEFAULT NULL,
  `candidate_users` TEXT NULL DEFAULT NULL,
  `customer_id` BIGINT NULL,
  `product_id` BIGINT NULL,
  `customer_general_data` JSON NULL,
  `product_general_data` JSON NULL,
  `start_time` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `end_time` DATETIME NULL DEFAULT NULL,
  PRIMARY KEY (`id`));
  
  
CREATE TABLE `cam-history`.`historic_variable_store` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `process_instance_id` varchar(255) COLLATE utf8_slovenian_ci NOT NULL,
  `customer_id` bigint(20) DEFAULT NULL,
  `product_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_historic_variable_store_process_inst_id` (`process_instance_id`)
);

Test process

In resources -> bpmn you can find the test process which can be used for testing the functionality. The process can be started using Camunda Web App. After process start, the token will wait in Human Task. At that time, you can check the table task_event - task will be registered with all additional data in it.

After completion of task, row in task_event table will be updated.

Updates...

In commit 35d0724 I was trying to solve the use case when there is a waiting state (signal or timer) before user task. In that case, if you restart the application when token is in a waiting state, the variable mapping (hash map) will disappear from memory and you cannot fetch customer and product references. Because of that, I decided to make a persistent variable store (as database table). If there are no references in hash map (memory) program will try to fetch references from store (database table).

First insert in historic_variable_store happened on variable updates. Also, the row for given process instance will be deleted when user task is created. Part of code:

variableMapping.remove(historicTaskInstance.getProcessInstanceId());
variableStoreService.deleteByProcessInstance(historicTaskInstance.getProcessInstanceId());

Running the project

• Execute schema.sql file
• Open pom.xml file and check the version of MySQL Driver (the 5.X.X is default version)
• Open application.yml and change driver-class-name (uncomment line)

Contribution/Suggestions

If someone is interested for contribution or have some suggestions please contact me on e-mail hedzaprog@gmail.com.

Author

Heril Muratović
Software Engineer

Mobile: +38269657962
E-mail: hedzaprog@gmail.com
Skype: hedza06
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LinkedIn: https://www.linkedin.com/in/heril-muratovi%C4%87-021097132/
StackOverflow: https://stackoverflow.com/users/4078505/heril-muratovic