This sample implements a fictional e-commerce store. It is different from most samples in that it shows many features of NServiceBus working together.
Users can order products from the website. Once orders are submitted, there is a window of time allocated for handling cancellations due to buyer's remorse. Once the order has been accepted, it is provisioned and made available for download.
The web application hosts the ECommerce endpoint. When a user presses Place Order on the website, the ECommerce endpoint sends a
SubmitOrder command to the Sales endpoint. Upon receiving a
SubmitOrder command the Sales endpoint will immediately publish an
OrderPlaced event with a request to be called back in 20 seconds (
BuyersRemorseIsOver). If the user does not cancel the order before the end of the buyer's remorse period, the Sales endpoint will publish an
The ECommerce endpoint subscribes to the
OrderAccepted events in order to update the web page. It does this by forwarding events to the client using SignalR.
If the user presses Cancel before the buyer's remorse period ends, the ECommerce endpoint sends a
CancelOrder command to the Sales endpoint which publishes an
OrderCancelled event instead of an
OrderAccepted event. The ECommerce endpoint subscribes to
OrderCancelled and updates the UI via SignalR to mark the order as cancelled.
Once an order is accepted, it can be provisioned. The ContentManagement endpoint subscribes to the
OrderAccepted event and sends a
ProvisionDownloadRequest message to the Operations endpoint. When Operations handles
ProvisionDownloadRequest it responds with a
ProvisionDownloadResponse message. When the response is received by ContentManagement it publishes a
DownloadIsReady event. The ECommerce endpoint subscribes to
DownloadIsReady to update the UI via SignalR.
The CustomerRelations endpoint subscribes to
OrderAccepted events. When a customer order is accepted, the CustomerRelations endpoint publishes a
ClientBecamePreferred event. This event has only one subscriber, CustomerRelations itself, which will use send the customer a welcome pack and a limited time offer when a customer becomes preferred.
In implementing the above workflow various aspects are highlighted:
Illustrates the use of the saga pattern to handle the buyer's remorse scenario.
The request/response pattern is illustrated for the product provisioning between the ContentManagement endpoint and the Operations endpoint.
The e-commerce endpoint is implemented as an ASP.NET application which uses SignalR to show feedback to the user.
The use of message headers and message mutator is illustrated when the user clicks on the checkbox on the e-commerce web page, which stops at the predefined breakpoints in the message handler code on the endpoints.
The use of encryption is illustrated by passing in the credit card number and the expiration date from the web site. The UnobtrusiveConventions defined in the ECommerce endpoint show how to treat certain properties as encrypted. Both the ECommerce and the Sales endpoint use Rijndael encryption and the encryption key is provided in the config file. If the messages are inspected in the queue, both the credit card number and the expiration date will show the encrypted values.