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IdentifierMapper

Primary Author: Thomas

Contents

  1. Overview
  2. Setup / Installation
  3. Exchange and Queue Settings
  4. Config
  5. Expectations
  6. Class Diagram

1. Overview

This service takes serialized Dicom file as DicomFileMessage messages and uses an ISwapIdentifiers to replace the top level DicomTag.PatientID tag for an anonymous representation. If there is no PatientID then the message is nacked. If the ISwapIdentifiers returns null then the message is nacked with the reason provided by string GetSubstitutionFor(string toSwap, out string reason).

2. Setup / Installation

  • Clone the project and build. Any NuGet dependencies should be automatically downloaded

  • Edit the yaml.default with the configuration for your environment

    • Pick an implementation of ISwapIdentifiers e.g. Microservices.IdentifierMapper.Execution.IdentifierSwapper and enter the full Type name into default.yaml IdentifierMapperOptions.SwapperType.
    • Specify the mapping table database details*
      • MappingConnectionString, the connection string to use to connect to the mapping server
      • MappingDatabaseType, either MicrosoftSQLServer or MYSQLServer
      • MappingTableName, the table on the mapping server that contains the identifier mapping table* (identifiable=>anonymous)
      • SwapColumnName, the column in the MappingTableName that will contain the expected (identifiable) input values to replace.
      • ReplacementColumnName, the column in the MappingTableName that contains the replacement values.

  • Decide if you want to use a Redis cache.

*The table/connection string details are at the disposal of the ISwapIdentifiers chosen. Some might ignore them completely or might manually create the mapping table themselves (e.g. ForGuidIdentifierSwapper)

3. Exchange and Queue Settings

Read/Write Type Config setting
Read DicomFileMessage IdentifierMapperOptions.QueueName
Write DicomFileMessage IdentifierMapperOptions.AnonImagesProducerOptions

Expects to receive control messages informing it to 'refresh' it's mapping table.

4. Config

YAML Section Purpose
RabbitOptions Describes the location of the rabbit server for sending messages to.
IdentifierMapperOptions Describes location of the mapping table (e.g. CHI=>EUPI), the Type responsible for mapping and all queue/exchange settings.
Command Line Options Purpose
CliOptions Allows overriding of which yaml file is loaded.

5. Redis

If you are using an ISwapper implementation that consults a large mapping database e.g. 10 million then you may benefit from using a Redis caching database. Install Redis and set the RedisHost option in the config file e.g.

IdentifierMapperOptions:
    SwapperType: "Microservices.IdentifierMapper.Execution.Swappers.TableLookupSwapper"
    RedisHost: localhost

All lookup results will be cached in the Redis server (both successful lookups and misses).

If you update your lookup table you will have to manually flush the Redis server (if desired).

6. Expectations

All identifier allocation is handled by the chosen ISwapIdentifiers. The only field considered is DicomTag.PatientID which should be the only patient identifier field loaded by any downstream processes.

You should ensure the integrity of your mapping table yourself through an appropriate schema (e.g. not null, primary keys) to prevent 1->Many mappings and blank mappings etc at data load time. It is not the job of the ISwapIdentifiers to handle this.

Data Failure States

  • Dicom file doesn't contain a DicomTag.PatientID
    • Nacked Test_BlankPatientIdentifier
  • PatientID not found by ISwapIdentifiers
    • Nacked Test_NoMatchingIdentifierFound

Environmental Failure States

  • Operation on loss of RabbitMQ connection:
    • No special logic
  • Operation on loss of access to mapping table:
    • Any Exception thrown by the ISwapIdentifiers will not be caught triggering a Fatal on the Consumer.

6. Class Diagram

Class Diagram