About the Replication Assurance Policy

Assured replication uses a Replication Assurance Policy to define the properties needed to ensure that replication has completed before the update response is returned to the client. Multiple policies can be defined, but only one policy is matched with a client update request. Each policy contains an evaluation order index that, together with an optional request and connection criteria, provides flexibility in matching a policy to request.

The Replication Assurance Policy defines local and remote assurance levels. A level defines how rigorous the policy should be when waiting for propagation of updates while local and remote distinguish servers in the same location versus servers in remote locations. Although optional, you should associate request or connection criteria with a policy to apply replication assurance appropriately.

PingDirectory server contains a default Replication Assurance Policy that is enabled with the local-level processed-all-servers assurance level. In addition to using the Default Replication Assurance Policy, any number of policies can be created and enabled. When a client request is received, the server iterates through the list of enabled policies according to each policy’s evaluation-order-index property. A smaller evaluation-order-index value (such as 1) has precedence over policies with larger evaluation-order-index values (such as 2, 3, 4, and so forth). The evaluation-order-index values do not need to be contiguous. The first policy that matches a request is associated with the operation.

The Replication Assurance Policy, which is defined on the PingDirectory server and not on the PingDirectoryProxy server, has the following properties:

Servers in a replication topology are not required to share a homogeneous set of policies. You can configure the Replication Assurance Policies differently on the replicas in a topology. For example, if you configure server A to match add operations to a processed-all-servers assurance level, and server B to match add operations to a local received-any-server level, then add operations received on server A have the assurance level of processed-all-servers and add operations received on server B have the assurance level of received-any-server.