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OpenLMIS Fulfillment Validator Extension Module

This example is meant to show an OpenLMIS 3.x Fulfillment Extension Module at work.

Prerequisites

  • Docker 1.11+

Quick Start

  1. Fork/clone this repository from GitHub.
git clone https://github.com/villagereach/selv-v3-fulfillment-extension.git
  1. Fork/clone openlmis-fulfillment repository from GitHub.
git clone https://github.com/OpenLMIS/openlmis-fulfillmentt.git
  1. To assemble the outputs of project and create jar file run docker-compose -f docker-compose.yml run builder.
  2. Edit configuration file extensions.properties from selv-v3-extensions-config repository to use your defined extension.
  3. Run builder for selv-v3-extensions-config and build image.
  4. Run selv-v3-ref-distro using docker-compose.selv-v3-fulfillment-extension.yml and check if your changes has been applied.

Example of extensions usage

General information

OpenLMIS allows extending or overriding certain behavior of service using extension points and extension modules. Every independent service can expose extension points that an extension module may utilize to extend its behavior. Extension point is a Java interface placed in the service. Every extension point has its default implementation that can be overridden. Extension modules can contain custom implementation of one or more extension points from main service.

Decision about which implementation should be used is made based on the configuration file extensions.properties. This configuration file specifies which modules (implementations) should be used for the Service's extension points. In selv-v3-extensions-configuration repository, there is an example of one such configuration file that specifies that a SequenceNumberGenerator module should be used for the extension point OrderNumberGenerator.

#Example extensions configuration
OrderNumberGenerator=SequenceNumberGenerator

The extension point OrderNumberGenerator is an ID defined by the interface OrderNumberGenerator.java, while the extension module SequenceNumberGenerator is an implementation of that interface whose name is a Spring Bean defined in SequenceNumberGenerator.java

Configuration file lives in independent service repository. Every extension module should be deployed as JAR. Example extension module and configuration file is published in the repository selv-v3-fulfillment-extension.

Following classes are example of extension points usage:

  • OrderNumberGenerator.java - sample extension point, that has Id defined in ExtensionPointId class.
  • Base36EncodedOrderNumberGenerator.java - default implementation of that interface, it has @Component annotation that contains its Id.
  • SequenceNumberGenerator.java - class extending AdjustmentReasonValidator interface from openlmis-fulfillment repository. It has @Component annotation that contains its Id.
  • ExtensionManager.java - class that has getExtensionByPointId method. It returns implementation of an extension class that is defined in configuration file for extension point with given Id.

Naming convention

The extension points' and extension modules' IDs should be unique and in UpperCamelCase. A situation where two extension modules have the same ID leads to undeterministic behavior - it is not possible to predict which bean will be used.

  • Extension points should be descriptive of the behavior that may be changed. For example "RequisitionOrderQuantityCalculation" instead of "OrderQuantity".
  • Extension Modules should describe the behaviour that is implemented, and the extension point that is being used. For example "RequisitionOrderQuantityCalculationAMC" and "RequisitionOrderQuantityCalculationISA".