source-code-structure.md

Source code structure

• .NET
• Node.js
• Web

.NET

The .NET solution consists of 7 projects:

• The Models project defines all the model classes required by RideShare
• The Shared project contains all the services which are used by the functions to provide different functionality
• The Seeder project contains some integration tests to pump trips through the solution
• The Drivers Function App project contains the Drivers APIs
• The Trips Function App project contains the Trips APIs
• The Passengers Function App project contains the Passengers APIs
• The Orchestrators Function App project contains the Orchestrators

The following are some notes about the source code:

• The Factory pattern is used to create static singleton instances via the ServiceFactory:

private static ISettingService _settingService = null;

public static ISettingService GetSettingService()
{
    if (_settingService == null)
    _settingService = new SettingService();

    return _settingService;
}

• The ISettingService service implementation is used to read settings from environment variables:

var seconds = _settingService.GetTripMonitorIntervalInSeconds();
var maxIterations = _settingService..GetTripMonitorMaxIterations();

• The ILoggerService service implementation sends traces, exceptions, custom events and metrics to the Application Insights resource associated with the Function App:

    // Send a trace
    _loggerService.Log($"{LOG_TAG} - TripCreated - Error: {error}");

    // Send an event telemetry
    _loggerService.Log("Trip created", new Dictionary<string, string>
    {
        {"Code", trip.Code },
        {"Passenger", $"{trip.Passenger.FirstName} {trip.Passenger.LastName}" },
        {"Destination", $"{trip.Destination.Latitude} - {trip.Destination.Longitude}" },
        {"Mode", $"{trip.Type}" }
    });

    // Send a metric telemetry
    _loggerService.Log("Active trips", activeTrips);

• IPersistenceService has two implementations: CosmosPersistenceService and SqlPersistenceService. The Azure Cosmos DB implementation is complete and used in the APIs while the SQL implementation is partially implemented and only used in the TripExternalizations2PowerBI handler to persist trip summaries to SQL.
• The CosmosPersistenceService assigns Cosmos DB IDs manually, which is a combination of the collection type and some identifier. Cosmos DB's ReadDocumentAsync retrieves really fast if an id is provided.
• The IsPersistDirectly setting is used mainly by the orchestrators to determine whether to communicate with the storage directly (via the persistence layer) or whether to use the exposed APIs to retrieve and update. In the reference implementation, the IsPersistDirectly setting is set to true.

Node.js

The nodejs folder contains the Archiver Function App with the following folder structure:

• The serverless-microservices-functionapp-triparchiver folder contains the Archiver Function App.
• The EVGH_TripExternalizations2CosmosDB folder contains the function to send data to the Archiver Collection in Azure Cosmos DB:
  • function.json: Defines the function's in (eventGridTrigger) and out (documentDB) bindings.
  • index.js: The function code that defines the data to be sent.
• .gitignore: Local Git ignore file.
• host.json: This file can include global configuration settings that affect all functions for this function app.
• local.settings.json: This file can include configuration settings needed when running the functions locally.

Web

The web folder contains the Vue.js-based SPA website with the following folder structure:

• The public folder contains the index.html page, as well as js folder that contains important settings for the SPA. The settings.sample.js file is included and shows the expected settings for reference. The settings.js file is excluded to prevent sensitive data from leaking. This file is added via the Web App's debug console (Kudu) after deploying the website.
• The src folder contains the bulk of the files:
  • api: these files use the http helper (utils/http.js) to execute REST calls against the API Management endpoints.
  • assets: site images.
  • components: Vue.js components, including a SignalR component that contains the client-side functions called by the SignalR Service.
  • store: Vuex store, which represents the state management components for the SPA site.
  • utils: utilities for authentication (wraps the Microsoft Authentication Library (MSAL)) and HTTP (wraps the Axios library)
  • views: Vue.js files for each of the SPA "pages".