Extended Distributed Calling Package for Umbraco

  • Dan Lister

The Extended Distributed Calling package allows developers to create and use Distributed Calling providers to cater for different scenarios. Specifically where a hard coded list of server addresses is not possible to obtain for use within Umbraco's Distributed Calling configuration. For example, when hosting an Umbraco application in an Amazon Elastic Load Balanced application. The Extended Distributed Calling package uses a specified provider to obtain a collection of server addresses. Once obtained, a cache refresh request is sent to each server. You can download the Extended Distributed Calling package from our.umbraco.org.


Add the following configuration section to web.config to configure and enable Extended Distributed Calling. As default, we've set-up the below example configuration to use the Amazon Distributed Calling provider:

The enabled attribute can be used to turn Extended Distributed Calling on or off. The user attribute must contain the user id which will be used to authenticate any cache refresh request. The type attribute must contain the fully qualified class name. The assembly attribute must contain the assembly name where the type resides.


To write your own provider, create a new class which implements the IExtendedDistributedCallingProvider interface. The interface contains one method which requires a list of addresses to be returned. To use your provider, change your type and assembly configuration in web.config to the your new provider. To get you started, the Extended Distributed Calling assembly contains the following providers for use within your Umbraco applications:

Amazon Distributed Calling

For use on scalable Amazon Elastic Load Balanced applications. Type and assembly details are as follows:

  • Type
  • Assembly

The provider requires the following Application Settings via web.config. These can either be manually or dynamically added via the AWS console:

The AWS_ACCESS_KEY_ID app setting must contain a valid access key to access the AWS API. The AWS_SECRET_KEY app setting must contain a valid secret key to access the AWS API. The AWS_ENV_NAME app setting must contain the name of the current ELB's environment. The AWS_REGION must contain the region of the current ELB's environment. The follow region values are accepted:

  • us-east-1
  • us-west-1
  • us-west-2
  • eu-west-1
  • ap-northeast-1
  • ap-southeast-1
  • ap-southeast-2
  • sa-east-1
  • us-gov-west-1
  • cn-north-1

Note: For the Amazon Distributed Calling provider to work correctly, each EC2 instance attached to the load balancer must be able to communicate with all other attached EC2 instances. To allow this, the EC2 instance security group must allow incoming HTTP calls from the ELB security group on port 80. Allowing this rule does not open up each EC2 instance to the public.


To raise a new bug, create an issue on the Github repository. To fix a bug or add new features, fork the repository and send a pull request with your changes. Feel free to add ideas to the repository's issues list if you would to discuss anything related to the package.