Inbound Message Flow

These components are involved in the flow of messages from one Government to another. Specifically, the receiving side of the equation.

Channel Observer

There is one of these workers for each distinct channel.

They are like listening posts. They observe every message on the channel, filter out the ones that originate from this jurisdiction, and send the rest to the Private Message API for processing.

This way the rest of the system can know about new messages, and does not need to know about the configuration of channels.

@startuml component observer [ Observer ] usecase relay [ Relay Inbound Messages ] observer -- relay queue channel relay -- channel component pmapi [ Private Message API ] boundary post [ POST newly received message ] relay -- post post --pmapi @enduml

Private Message API

When a message is sent by another jurisdiction to this one, the Channel Observer component associated with that channel uses this private API to process the mesaages.

This is where many channels funnel into the one system.

The implementation is /intergov/apis/message_rx_api

The specific business logic code is in the class EnqueueMessageUseCase in the file /intergov/use_cases/enqueue_messages.py.

component rx_api [ Private Message Api ] usecase enqueue_message [ Enqueue Message ] boundary post [ post message ] database bc_inbox [ bc inbox ] rx_api -- enqueue_message enqueue_message -- post post -- bc_inbox

Object Spider

This worker process is a “spider” in the same sense of the word as used to describe the things that search engines use to maintain their index of web pages.

Unlike a search index spider this does not fetch web pages. It fetches the objects (files, documents, etc) that are the subject of G2G messages.

This component assumes the other Government is providing an interface that conforms with the edi3 Document API spec.

class intergov.processors.obj_spider.ObjectSpider[source]

Iterate over the RetrieveAndStoreForeignDocumentUseCase.

@startuml component spider [ Object Spider ] cloud internet usecase uc [ Retrieve And Store Foreign Documents ] spider -- uc uc -- internet database obj_lake [ object lake ] boundary lake_exists [ check if object exists ] uc -- lake_exists lake_exists -- obj_lake boundary lake_store [ store object ] uc -- lake_store lake_store -- obj_lake database obj_acl [ object ACL ] boundary allow_access [ allow access ] uc -- allow_access allow_access -- obj_acl database ret [ object retrieval ] boundary ret_get_job [ get job ] uc -- ret_get_job ret_get_job -- ret boundary ret_del_job [ delete job ] uc -- ret_del_job ret_del_job -- ret boundary ret_post_job [ post job ] uc -- ret_post_job ret_post_job -- ret @enduml

class intergov.use_cases.retrieve_and_store_foreign_documents.RetrieveAndStoreForeignDocumentsUseCase(jurisdiction, object_retrieval_repo, object_lake_repo, object_acl_repo)[source]

Processes single request from the queue to download some remote document.

The process is recursive. If an object has sub-objects, add more jobs to download them later.

Note

  • returns None if the object has already been downloaded

  • returns True in case of success

  • raises exceptions for errors