google-nomulus/docs/code-structure.md

Code structure

This document contains information on the overall structure of the code, and how particularly important pieces of the system are implemented.

Dagger dependency injection

Bazel build system

Flows

Commit logs and backups

Cursors

Mapreduces

Actions and servlets

Foreign key indexes

Point-in-time accuracy

Guava

EPP resource hierarchy

Poll messages

Poll messages are the mechanism by which EPP handles asynchronous communication between the registry and registrars. Refer to RFC 5730 Section 2.9.2.3 for their protocol specification.

Poll messages are stored by the system as entities in Datastore. All poll messages have an event time at which they become active; any poll request before that time will not return the poll message. For example, every domain when created speculatively enqueues a poll message for the automatic renewal of the domain a year later. This poll message won't be delivered until that year elapses, and if some change to the domain occurs prior to that point, such as it being deleted, then the speculative poll message will be deleted and thus never delivered. Other poll messages are effective immediately, e.g. the poll message generated for the owning registrar when another registrar requests the transfer of a domain. These messages are written out with an event time of when they were created, and will thus be delivered whenever the registrar next polls for messages.

PollMessage is the abstract base class for the two different types of poll messages that extend it:

• Autorenew - A poll message corresponding to an automatic renewal of a domain. It recurs annually.
• OneTime - A one-time poll message used for everything else.

Queries for poll messages by the registrar are handled in PollRequestFlow, and poll messages are ACKed (and thus deleted) in PollAckFlow.

Security