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JPA View

Purpose#

The JPA View is component responsible for creating read-projections of tasks and business data entries. It currently implements Datapool View API and Taskpool API and persists the projection as entities and relations in a RDBMS using JPA. It is useful if the JPA persistence is already used in the project setup.

Features#

  • stores representation of business data entries
  • stores representation of process definitions
  • stores representation of process instances
  • provides single query API supporting single and subscription queries

Configuration options#

In order to activate the JPA View implementation, please include the following dependency on your classpath:

<dependency>
  <groupId>io.holunda.polyflow</groupId>
  <artifactId>polyflow-view-jpa</artifactId>
  <version>${polyflow.version}</version>
</dependency>

The implementation relies on Spring Data JPA and needs to activate those. 

@Configuration
@EnablePolyflowJpaView
public class MyViewConfiguration {

}

In addition, configure a database connection to database using application.properties or application.yaml:

spring:
  jpa:
    show-sql: false
    open-in-view: true # disable JPA warning
  datasource:
    url: <jdbc-connnection-string>
    username: <db-user>
    password: <db-password>

The JPA view uses a special facility for creating search indexes on unstructured payload. For this purpose it converts the payload into a recursive map structure (in which every primitive type is a leaf and every complex type is decomposed via the map) using Jackson ObjectMapper and then create search indexes for all property paths (myObj1.myProperty2.myOtherEmbeddedProperty3) and their values. You can provide some configuration of this indexing process by the following configuration options:

polyflow.view.jpa:
  stored-items: task, data-entry, process-instance, process-definition
  payload-attribute-level-limit: 2
  data-entry-filters:
    include: myProperty2.myOtherEmbeddedProperty3, myProperty2.myOtherEmbeddedProperty2
#    exclude: myProperty
  task-filters:
    exclude: processVariableWithVeryLongText

In the example above you see the configuration of the limit of keying depth and usage of include/exclude filters of the keys. In addition, the stored-items property is holding a set of items to be persisted to the database. The possible values of stored items are: task, data-entry, process-instance and process-definition. By setting this property, you can disable storage of items not required by your application and save space consumption of your database. The property defaults to data-entry.

The attributes data-entry-filters and task-filters hold include / exclude lists of property paths which will be taken in consideration during the search index creation.

Note

Please make sure you understand that the payload enrichment performed during collection and indexing for search are two different operations. It is perfectly fine to have a large JSON payload attached to the task, but it makes no sense to make the entire payload searchable, at lease using JPA View.

Entity Scan#

The JPA View utilizes Spring Data repositories and Hibernate entities inside the persistence layer. As a result, it declares a @EntityScan and @EnableJpaRepositories annotations pointing at the corresponding locations. If you are using Spring Data JPA on your own, you will need to add the @EntityScan and @EnableJpaRepositores annotation pointing at your packages. In addition, please check Persistence configuration.

Logging#

The view implementation provides runtime details using standard logging facility. If you want to increase the logging level, please setup it e.g. in your application.yaml:

logging.level:
  io.holunda.polyflow.view.jpa: DEBUG

DB Tables#

The JPA View uses several tables to store the results. These are:

  • PLF_DATA_ENTRY: table for business data entries
  • PLF_DATA_ENTRY_AUTHORIZATIONS: table for authorization information of data entries
  • PLF_DATA_ENTRY_PAYLOAD_ATTRIBUTES: table for data entry attribute search index
  • PLF_DATA_ENTRY_PROTOCOL: table for data entry protocol entry (users, groups)
  • PLF_PROC_DEF: table for process definitions
  • PLF_PROC_DEF_AUTHORIZATIONS: table for authorization information of process definitions
  • PLF_PROC_INSTANCE: table for process instances
  • PLF_TASK: table for user tasks
  • PLF_TASK_AUTHORIZATIONS: table for authorization information of user tasks
  • PLF_TASK_CORRELATIONS: table for user task correlation information
  • PLF_TASK_PAYLOAD_ATTRIBUTES: table for user task attribute search index
  • TRACKING_TOKEN: table for Axon Tracking Tokens

If you are interested in DDLs for the view, feel free to generate one using the following call of Apache Maven mvn -Pgenerate-sql -f view/jpa. Currently, DDLs for the databases H2, MSSQL and PostgreSQL are generated into target/ directory.