| To illustrate Espresso, we have created an instance of the familiar Northwind database at our site.
When you first use Espresso, we use this database to illustrate the Connect process, the resulting API and UI that are created through Schema Discovery.
Further, we have pre-loaded a set of rules, resources and security settings you can explore.
The rules are depicted here, illustrating
- the "cocktail napkin" design (lower right)
- the logic dependencies (diagram), and
- the Use Cases solved by these 5 rules
Northwind has the schema shown below.
The Espresso Tour pre-creates the rules shown below, so you can explore them. While you might have conceived the rules for Place Order / Check Credit, they operate on any RESTful update against the data.
So, you can alter an
orderdetails.Quantity, and the logic will:
- Recompute the orderdetails.Amount, since it is dependent on the quantity
- Adjust the orders.AmountTotal with a 1 row SQL update (not a select sum), since it is dependent on the amount
- Adjust the customers.balance
- Verify this does not exceed the credit limit (else an exception is thrown and the transaction is rolled back)
In exactly the same manner, this logic is automatically re-used
over all related transactions. This automatic change detection, propagation, SQL and transaction management results in meaningful reductions
in boilerplate code.
Below are some example of Live Browser running on Northwind.
"Drill Down" to Product
If we drill down on Chai on the screen above, we see this. The Order Details are the orders for Chai, and the system has used Predictive Joins to join in the Ship Name from the orderdetails.