= Data handling overview
:description: How to effectively use the different kinds of data available within Bonita Platform

How to effectively use the different kinds of data available within Bonita Platform

In a BPM-based application, use:

* xref:define-and-deploy-the-bdm.adoc[Business variables] for information that:
 ** is mostly used by Bonita
 ** has meaning after a process instance is archived
 ** is used at several places in the process
 ** is read by a process to orientate its flow
 ** is shared across several process instances
 ** is displayed in an application page
* Task-level xref:specify-data-in-a-process-definition.adoc[process variables] for:
 ** intermediate computation results (for example a connector result to be used as input of the next connector)
 ** information that is private to the process, not used elsewhere in the application
* Pool-level xref:specify-data-in-a-process-definition.adoc[process variables] for information that:
 ** can be read by the process to orientate its flow
 ** can be used at several places in the process
 ** is private to the process, not used elsewhere in the application
* External databases, with xref:connectivity-overview.adoc[connectors], for information that:
 ** is used by multiple applications besides Bonita

Key benefits of using business data:

* Control of indexing strategy
* Definition of custom queries to efficiently read the data
* Full control of lifecycle of the data through the set of processes that handle it (add, update and delete)
* Improved performance compared with process variables or external databases
* Easier application maintenance

An application page accesses business data using the {openApiUrl}/{openApiLatestVersion}/#tag/BDM[bdm REST API]. A page also contains page xref:variables.adoc[variables], which have no meaning outside the page.

The data that is passed from a form to a process is defined using a xref:contracts-and-contexts.adoc[contract]. Define a contract for process instantiation and for each human task.
These contracts are part of the process definition.
A form has access to business data and documents using the xref:contracts-and-contexts.adoc[context] and the xref:rest-api-overview.adoc[REST API].
A form also contains form xref:variables.adoc[variables], which have no meaning outside the form.
