Use events between BCs

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I would recommend against sending the PlaceOrder command from the Basket BC to the Orders BC. Commands between BCs introduce behavioral coupling. Instead, use an event that represents what happened in the Basket BC (e.g. "OrderPlaced" if that's how it's described in the domain).

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* ID: c5ab515b-a39a-983d-2a09-13ca5ccf5125
* Version Independent ID: 82f66a0e-6ad3-c419-36cb-ecc985b9b192
* Content: [Asynchronous message-based communication](https://docs.microsoft.com/en-us/dotnet/architecture/microservices/architect-microservice-container-applications/asynchronous-message-based-communication)
* Content Source: [docs/architecture/microservices/architect-microservice-container-applications/asynchronous-message-based-communication.md](https://github.com/dotnet/docs/blob/main/docs/architecture/microservices/architect-microservice-container-applications/asynchronous-message-based-communication.md)
* Product: **dotnet-architecture**
* Technology: **microservices**
* GitHub Login: @nishanil
* Microsoft Alias: **nanil**