1.2 Create the project

dotnet new web -n Shopfront
cd Shopfront

Package versions live in one place, Directory.Packages.props, beside the project file. Create it:

<Project>
  <PropertyGroup>
    <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
    <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
  </PropertyGroup>
 
  <ItemGroup>
    <PackageVersion Include="Trax.Core" Version="1.68.0" />
    <PackageVersion Include="Trax.Effect" Version="1.68.0" />
    <PackageVersion Include="Trax.Effect.Data.InMemory" Version="1.68.0" />
    <PackageVersion Include="Trax.Effect.Provider.Parameter" Version="1.68.0" />
    <PackageVersion Include="Trax.Mediator" Version="1.68.0" />
  </ItemGroup>
</Project>

Every Trax package releases at the same version, so they are pinned together, to an exact version. Then replace Shopfront.csproj with this:

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <!-- The tests live under tests/, in a project of their own. -->
    <DefaultItemExcludes>$(DefaultItemExcludes);tests/**</DefaultItemExcludes>
  </PropertyGroup>
 
  <ItemGroup>
    <PackageReference Include="Trax.Core" />
    <PackageReference Include="Trax.Effect" />
    <PackageReference Include="Trax.Effect.Data.InMemory" />
    <PackageReference Include="Trax.Effect.Provider.Parameter" />
    <PackageReference Include="Trax.Mediator" />
  </ItemGroup>
</Project>

Trax.Core holds the chain and the types it returns, Trax.Effect holds trains and junctions, Trax.Effect.Data.InMemory keeps a record of every run in memory, Trax.Effect.Provider.Parameter writes each run's input and output into that record, and Trax.Mediator finds our trains and hands them to whoever asks.

By the end of the chapter the project looks like this:

Shopfront/
├── Directory.Packages.props
├── Shopfront.csproj
├── Program.cs
├── Inventory/
│   └── Catalogue.cs
├── Payments/
│   ├── IPaymentProvider.cs
│   └── FakePaymentProvider.cs
└── Trains/
    └── PlaceOrder/
        ├── PlaceOrderInput.cs
        ├── PlaceOrderOutput.cs
        ├── IPlaceOrderTrain.cs
        ├── PlaceOrderTrain.cs
        ├── Junctions/
        │   ├── PriceCartJunction.cs
        │   ├── ReserveStockJunction.cs
        │   ├── TakePaymentJunction.cs
        │   └── ConfirmOrderJunction.cs
        └── Models/
            ├── OrderLine.cs
            ├── PricedCart.cs
            ├── PricedLine.cs
            ├── StockReservation.cs
            └── Payment.cs

The tests go in tests/, which chapter 2 fills.

Each train gets a folder under Trains/. Its top level is the train's contract: the input, the output, the interface and the train. Its junctions go in Junctions/, one file each, and every other type it uses goes in Models/. The shop itself, what it sells and how it is paid, lives outside Trains/, because more than one train will use it. Organize trains in a project has the layout on its own.

SDK Reference

Junctions | Chain | Run / RunEither | TrainException | AddTrax / AddEffects | UseInMemory | SaveTrainParameters | AddMediator

Next: 1.3 The shop