Skip to main content

Developing an Application

 

OutSystems

Understand Strong and Weak Dependencies

Depending on the type of element exposed by a producer module, OutSystems will generate a strong dependency or a weak dependency between the producer module and its consumers.

Strong Dependencies

When a consumer module has a strong dependency to a producer, the producer logic is executed just as if it is defined in the consumer module. They run in the same request, share the same transaction, session variables, site properties, etc.

In runtime, the consumer module needs to know both the signature and the implementation of the element exposed by the producer to be able to reuse it. For this reason, when the producer changes the signature or the implementation of the exposed element, the consumer module becomes outdated and needs to be republished to start using the latest producer version.

Reusing the following elements, will make the consumer’s dependency to the producer a strong dependency:

  • Server Actions
  • Client Actions
  • Web and Mobile Blocks
  • Images
  • Resources
  • Scripts
  • Themes
  • Roles
  • Processes
  • Process Activities

If the consumer is reusing more than one element exposed by the same producer module, and at least one of the elements belongs to the list above, the consumer has a strong dependency to that producer.

Weak Dependencies

When a consumer module has a weak dependency to a producer, depending on the type of the producer’s element reused by the consumer, one of the following happens:

  • Elements having associated logic, such as actions or screens, run in the context of the producer’s request. Changes in the producer implementation take immediate effect in the consumer.

  • Data type elements, such as entities or structures, are defined only by the signature (there is no associated logic). Queries over reused entities run in the same transaction as the consumer logic. Changes in entities take immediate effect in the database.

In runtime, the consumer module only needs to know the signature of the element to be able to reuse it. For this reason, when the producer changes only the implementation of the exposed elements, the consumer module does not become outdated and the latest producer version is immediately available to the consumer in runtime.

Reusing the following elements, will make the consumer’s dependency to the producer a weak dependency:

  • Web Screens
  • Service Actions
  • Database Entities
  • Local Storage Entities
  • Static Entities
  • Structures

If the consumer is reusing more than one element exposed by the same producer module, the consumer has a weak dependency to that producer only if all the elements belong to the list above.

  • Was this article helpful?