Unique ID System Integration

Generally speaking, a unique ID system ensures that a person has only one unique ID for an organization even if the person is represented in multiple roles, such as an individual who is both a staff member and parent at a school. 

Many organizations have an existing implementation of a unique ID system. The Ed-Fi ODS / API does not replace an organization’s unique ID system. Instead, it provides clear extension points for platform developers to integrate with their existing system, while also providing clients with a standardized API for integrating identity management into their applications.

The Ed-Fi ODS / API provides two points of integration with unique ID systems. The first integration point provides a means for the API to validate the unique ID values being supplied by clients, and the second is an optional set of endpoints for clients to create and retrieve unique IDs for person records including students, staff, and parents.

The Ed-Fi ODS / API ships without unique ID validation. In the as-shipped distribution, its identity management endpoints are configured to return a 501 - Not Implemented response. Integration development work is required to connect to an enterprise unique ID system. This documentation contains conceptual and how-to material about connecting to an existing unique ID system.

Unique ID System Integration Models

When planning an API implementation, platform hosts must select an approach that best serves their enterprise's needs: an integrated unique ID system model (shortened to "integrated model," below), or a non-integrated unique ID system model ("non-integrated," below).

Within the integrated model, there are two facets: unique ID validation and identity management. Minimally, support for validation is expected. Optionally, the platform host may also choose to support the identity management endpoints.

Model 1. Integrated Unique ID System Model

This model is suitable when an external system, often a commercial product, is the authoritative source for unique IDs and can be wired into the ODS / API. In this model, an external unique ID system always defines the unique ID for students, staff, and parent entities and clients are expected to pass valid unique IDs to the ODS / API.

Distinguishing characteristics of this model include:

• Unique IDs are established outside the context of the ODS / API by the external unique ID system.
• Client applications are expected to supply valid unique IDs to the ODS / API. To accomplish this they may either:
  • Use the Ed-Fi /identities endpoint to search identities and create new unique IDs as necessary.
  • Follow a process defined outside the scope of the ODS / API to obtain appropriate unique ID values.
• When new person-entities are created in the ODS / API, the existence of the unique ID is validated against the external system automatically. Client applications do not define the unique ID values.

This model can support fully integrated unique ID management, but it does make some assumptions about the system flow. An outline of an expected system flow follows.

Client-Side ID Lookup in the Integrated Model

When the ODS / API platform supports an integrated model with identity management for establishing a unique ID, client applications will need some process for looking up that unique ID value. This section provides a system flow that most clients will follow to look up a unique ID through the Ed-Fi ODS / API. 

The unique ID for a person can be obtained from the /identities endpoints in the Ed-Fi ODS / API. The workflow for clients to create and obtain IDs are described below. For the purposes of this example, the workflow will focus on the use case of creating a new student record, but the same general flow applies to staff and parent records.

It is assumed that once a unique ID is obtained by a client, it will be stored in client applications as a way to easily sync data between the client and platform from that point forward.

A description of each step follows.

• Step 1. Execute a GET /identities with the first name, last name, sex, and date of birth.
• Step 2. Show the scored results to the user to let them select the correct identity.
• Step 3. Create a new identity using POST /identities if the user indicates an appropriate match does not already exist.
• Step 4. Save the resulting unique ID value in the client application for use when sending the person's data to the Ed-Fi ODS / API.

Now that a unique ID has been obtained, it can be used by clients when referring to that student.

Model 2. Non-Integrated Unique ID System Model

This model is suitable when platform hosts choose not to wire in or link to an external unique ID system. In this model, platform hosts provide guidance to clients on how to acquire or assign a unique ID out of band. A common approach is to instruct clients to acquire a unique ID from an enterprise system and subsequently pass that value to the ODS / API when creating new person entities.

Distinguishing characteristics of this model include:

• Client applications are responsible for populating the unique ID for person entities.
• The API performs no validation on the incoming unique IDs during person entity creation — unique ID values are treated as just another data element for the purposes of creation (though uniqueness is enforced by the API).

This model requires no system integration work from a platform host, but it relies on specific guidance being provided to client application developers.

Integration Model Comparison

The above models are fundamentally different for the platform host. But, from a client system perspective, the change is limited to whether or not the values that the client application supplies for the unique IDs are validated against an external system. In some scenarios, the client could conceivably be responsible for assigning the unique ID value, but exactly how that value should be derived should be agreed upon with the host.

Key Integration Steps for Unique ID Validation

Implement the Unique ID to Id Value Mapper

The IUniqueIdToIdValueMapper interface enables the API to use the supplied unique ID value to resolve and assign the resource identifier (Id) property of the person entity appropriately. Implicit in that interaction with the external system is a validation that the supplied unique ID already exists.

public interface IUniqueIdToIdValueMapper
{
    PersonIdentifiersValueMap GetId(string personType, string uniqueId);
    PersonIdentifiersValueMap GetUniqueId(string personType, Guid id);
}

public class PersonIdentifiersValueMap
{
    public int Usi { get; set; }
    public Guid Id { get; set; }
    public string UniqueId { get; set; }
}

The personType argument in the two methods defined by the interface will contain one of the following values upon invocation: Student, Staff, or Parent. In some integrations, this distinction may not be relevant and the argument can be ignored.

Upon return, the PersonIdentifiersValueMap's Usi property is not used and can be left as the default value (0).

Enabling the Unique Id Integration for Validation

The unique ID system integration feature is enabled using the ApiSettings:Features:UniqueIdValidation configuration setting in the appsettings.json file of the EdFi.Ods.WebApi project. While this registers and configures all the supporting components for performing unique ID validation, the custom implementation of the IUniqueIdToIdValueMapper will still need to be registered with the container. To register custom implementation, add registration to ApplyConfigurationSpecificRegistrations method in the UniqueIdIntegrationModule class as shown below: 

namespace EdFi.Ods.Features.Container.Modules
{
    public class UniqueIdIntegrationModule : ConditionalModule
    {
        ...
        public override void ApplyConfigurationSpecificRegistrations(ContainerBuilder builder)
        {
            ...  
            //Add registration of custom implementation
            builder.RegisterType<My.Custom.UniqueIdToIdValueMapper>()
                .As<IUniqueIdToIdValueMapper>()
                .SingleInstance()
        }
    }
}

Sample custom implementation could be: 

    public class My.Custom.UniqueIdToIdValueMapper : IUniqueIdToIdValueMapper
    {
        public PersonIdentifiersValueMap GetId(string personType, string uniqueId)
        {
            return Get(personType, uniqueId);
        }

        public PersonIdentifiersValueMap GetUniqueId(string personType, Guid id)
        {
            return Get(personType, id);
        }

        private PersonIdentifiersValueMap Get(string personTypeName, string uniqueId)
        {
            var results = new PersonIdentifiersValueMap { UniqueId = uniqueId };

            ValidatePersonType(personTypeName);

            using (var db = new UniqueIdIntegrationContext())
            {
                var uniqueIdMapping = db.UniqueIdPersonMappings.FirstOrDefault(mapping => mapping.UniqueId == uniqueId);

                if (uniqueIdMapping == null)
                    return results;

                results.Id = uniqueIdMapping.Id;
            }

            return results;
        }

        private PersonIdentifiersValueMap Get(string personTypeName, Guid id)
        {
            var results = new PersonIdentifiersValueMap { Id = id };

            ValidatePersonType(personTypeName);

            using (var db = new UniqueIdIntegrationContext())
            {
                var uniqueIdMapping = db.UniqueIdPersonMappings.FirstOrDefault(mapping => mapping.Id == id);

                if (uniqueIdMapping == null)
                    return results;

                results.UniqueId = uniqueIdMapping.UniqueId;
            }

            return results;
        }

        private static void ValidatePersonType(string personTypeName)
        {
            if (!PersonEntitySpecification.IsPersonEntity(personTypeName))
                throw new ArgumentException(
                    string.Format("Invalid person type '{0}'. Valid person types are: {1}", personTypeName,
                                  "'" + String.Join("','", PersonEntitySpecification.ValidPersonTypes) + "'"));
        }
    }
    public class UniqueIdIntegrationContext : System.Data.Entity.DbContext
    {
        public UniqueIdIntegrationContext(string connectionString)
            : base(connectionString)
        {
        }

        public UniqueIdIntegrationContext()
            : base()
        {
        }

        public DbSet<UniqueIdPersonMapping> UniqueIdPersonMappings { get; set; }
    }


    public class UniqueIdPersonMapping
    {
        [Key]
        public Guid Id { get; set; }

        [StringLength(32)]
        public string UniqueId { get; set; }
    }

This approach resolves supplied unique ID values to resource identifier (Id) records in the ODS using UniqueIdPersonMapping table: 

-- 
IF (NOT EXISTS (SELECT * FROM sys.schemas WHERE name = 'uid'))  
BEGIN 
    EXEC ('CREATE SCHEMA [uid] AUTHORIZATION [dbo]') 
END 
GO

CREATE TABLE [uid].UniqueIdPersonMapping
(
       Id uniqueidentifier NOT NULL,
       UniqueId nvarchar(32) NOT NULL,
);
GO

ALTER TABLE [uid].UniqueIdPersonMapping ADD CONSTRAINT PK_UniqueIdMapping PRIMARY KEY CLUSTERED (Id);
ALTER TABLE [uid].UniqueIdPersonMapping ADD CONSTRAINT UI_UniqueIdPersonMapping_UniqueId UNIQUE NONCLUSTERED (UniqueId);
GO

Technical Details of How Unique ID Integration Works

The UniqueIdIntegrationModule class makes the necessary modifications to adjust the API to operate in an integrated fashion with the external Unique ID system. Specifically, that installer performs the following tasks:

• Registers the IUniqueIdToIdValueMapper so that IDs and Unique IDs can be retrieved from the external system.
• Registers the IPersonUniqueIdToIdCache with an implementation that caches the UniqueId-to-Id mappings and calls the value mapper only when needed (for performance reasons).
• Registers a decorator for the IUpsertPipelineStepsProvider which inserts a PopulateIdFromUniqueIdOnPeople step in the processing of all PUT/POST requests just prior to persisting the entity model. This step only engages on person-type entities, but then it looks for an uninitialized Id property on the entity and calls the aforementioned IPersonUniqueIdCache to obtain the corresponding Id for the supplied UniqueId value. It then marks this Id as server-assigned to allow the API to create the resource if needed. (This is because v3.x of the Ed-Fi ODS / API no longer allows clients to assign IDs — they are now either assigned via UniqueId integration or they are initialized automatically during NHibernate persistence).
• Registers two entity validators (which are executed just prior to NHibernate persistence):
  • EnsureUniqueIdAlreadyExistsEntityValidator. This validator relies on the presence of the PopulateIdFromUniqueIdOnPeople step (which ensures the Id property is properly initialized even if the entity hasn't been persisted yet). When UniqueId integration is configured, if the Id hasn't been assigned by the time the entity is being validated (just prior to NHibernate persistence), then it is an indication that the UniqueId could not be resolved in the PopulateIdFromUniqueIdOnPeople step and a validation error is raised.
  • UniqueIdNotChangedEntityValidator. This validator also relies on the presence of the PopulateIdFromUniqueIdOnPeople step (which ensures the Id property has a relevant value before the entity is persisted the first time), and looks up the UniqueId using the IPersonUniqueIdCache. The UniqueId value returned from the cache should match the value actually assigned on the incoming entity. If it doesn't match, it indicates that the client is effectively trying to change the UniqueId value (through a PUT request), and a validation error is raised.

Key Integration Steps for Identity Management

Implement IIdentityService

Integrating your unique ID system with the Ed-Fi ODS / API requires a custom implementation of the IIdentityService interface. When properly registered, this code is called for each of the /identities API calls received by the Ed-Fi ODS / API.

The EdFi.Ods.Features.IdentityManagement project contains the definitions for all artifacts (e.g., interfaces, requests, responses) related to identity management integration. The placeholder implementation of the IIdentityService interface is located in the EdFi.Ods.Features project in the EdFi.Ods.Features.IdentityManagement namespace.

public interface IIdentityService<in TCreateRequest, in TSearchRequest, TSearchResponse, TIdentityResponse>
    where TCreateRequest : IdentityCreateRequest
    where TSearchRequest : IdentitySearchRequest
    where TSearchResponse : IdentitySearchResponse<TIdentityResponse>
    where TIdentityResponse : IdentityResponse
{
    IdentityServiceCapabilities IdentityServiceCapabilities { get; }

    Task<IdentityResponseStatus<string>> Create(TCreateRequest createRequest);

    Task<IdentityResponseStatus<TSearchResponse>> Find(params string[] findRequest);

    Task<IdentityResponseStatus<TSearchResponse>> Search(params TSearchRequest[] searchRequest);
}

The identities are represented by a generic type argument that is based on the IdentityResponse class, which is defined as follows:

public class IdentityResponse
{
	public string UniqueId { get; set; }
	public decimal Score { get; set; }
	public string LastSurname { get; set; }
	public string FirstName { get; set; }
	public string MiddleName { get; set; }
	public string GenerationCodeSuffix { get; set; }
	public string SexType { get; set; }
	public DateTime? BirthDate { get; set; }
	public int? BirthOrder { get; set; }
	public Location BirthLocation { get; set; }
}

Enabling the Identity Management API Endpoints

The identity management feature is enabled using the "ApiSettings:Features:IdentityManagement" configuration setting in the appsettings.json file of the EdFi.Ods.WebApi project. While this registers and configures all the supporting components for the API endpoints, the custom implementation of the IIdentityService will need to be registered with the container separately.

using Autofac;
using EdFi.Common.Configuration;
using EdFi.Ods.Common.Configuration;
using EdFi.Ods.Common.Container;
using My.Custom.IdentityService
  
namespace EdFi.Ods.Features.Container.Modules
{
    public class IdentityModule : ConditionalModule
    {
        public IdentityModule(ApiSettings apiSettings) : base(apiSettings, nameof(IdentityModule)) { }
  
        public override bool IsSelected() => IsFeatureEnabled(ApiFeature.UniqueIdValidation);
  
        public override void ApplyConfigurationSpecificRegistrations(ContainerBuilder builder)
        {
            builder.RegisterType<IdentitiesControllerOverrideConvention>()
                .As<IApplicationModelConvention>()
                .SingleInstance();

            // Register your implementation using the default models here
            //     (or see the article How To: Extend the Ed-Fi Identities API).
            builder.RegisterType<UnimplementedIdentityService>()
                .AsImplementedInterfaces()
                .SingleInstance();
        }
    }
}