A project that demonstrates how to use Java Futures
There are two use cases. The first is a travel use case that runs Hotel, Airline and Car Rental reservations in parallel.
The second use case is a commerce scenario that runs futures in two sequential styles. The first style is to run the activities in the use case as a sequence of blocking CompletableFuture<T>s.
The second style runs the activites a a chain of blocking CompletableFuture<T>s.
In both styles, the sequence of futures gets an order and then pays for the order, ships the order, delivers the order and then finally confirms the order.
The project is Java code that runs in the Maven framework.
Step 1: Confirm Java is installed.
java -versionYou'll get output similar to the following. If not, install the Java SDK.
openjdk version "21" 2023-09-19
OpenJDK Runtime Environment (build 21+35-2513)
OpenJDK 64-Bit Server VM (build 21+35-2513, mixed mode, sharing)
Step 2: Confirm Maven is installed on your host machine
mvn --versionYou'll get output similar to the following. If not, install Maven.
Maven home: /usr/share/maven
Java version: 18.0.2, vendor: Oracle Corporation, runtime: /usr/lib/jvm/jdk-18.0.2
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.19.0-46-generic", arch: "amd64", family: "unix"
Step 3: Do some Maven housecleaning
Run the following command in a terminal window to create a fresh Maven application environment:
mvn clean package installExecute the following code in a terminal window to run the Travel use case code:
mvn exec:java -Dexec.mainClass="futuresdemo.TravelProgram"You'll get output similar to the following:
Start time: 2024-02-19 16:56:45
Booking hotel, airline, and car rental reservations in parallel using CompletableFuture.
Airline booking started at: 2024-02-19 16:56:45
Hotel booking started at: 2024-02-19 16:56:45
CarRental booking started at: 2024-02-19 16:56:45
Airline booking ended at: 2024-02-19 16:56:47 and took 2 seconds.
CarRental booking ended at: 2024-02-19 16:56:50 and took 5 seconds.
Hotel booking ended at: 2024-02-19 16:56:55 and took 10 seconds.
Confirmations:
Confirmation id: 407e624c-bca5-498d-84a8-b3a611b78951 message: Hotel booking completed business type: hotel
Confirmation id: b94b3606-a009-41b9-8ca5-43f4e6cb019c message: Airline booking completed business type: airline
Confirmation id: 7ccd20cb-ba9f-4e6e-903f-686522c974a7 message: CarRental booking completed business type: car rental
End time: 2024-02-19 16:56:55
Total time: 10 seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10.277 s
[INFO] Finished at: 2024-02-19T16:56:55-08:00
[INFO] ------------------------------------------------------------------------
Execute the following code in a terminal window to run the Commerce use case code:
mvn exec:java -Dexec.mainClass="futuresdemo.SequenceCommerceProgram"You'll get output similar to the following:
Start time: 2024-02-19 16:55:41
Running a sequential business process
Dispatcher started at 2024-02-19 16:55:41
Shipped: Order 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5, ended at 2024-02-19 16:55:42 and took 1 seconds
Order: 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5 is pending
Payment started at 2024-02-19 16:55:42
Shipped: Order 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5, ended at 2024-02-19 16:55:44 and took 2 seconds
Order: 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5 is paid
Shipper started at 2024-02-19 16:55:44
Shipped: Order 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5, ended at 2024-02-19 16:55:47 and took 3 seconds
Order: 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5 is shipped
Delivery started at 2024-02-19 16:55:47
Shipped: Order 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5, ended at 2024-02-19 16:55:57 and took 10 seconds
Order: 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5 is delivered
Confirmation started at 2024-02-19 16:55:57
Shipped: Order 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5, ended at 2024-02-19 16:55:58 and took 1 seconds
Order: 7db49d8c-badc-4663-99d1-dcc7c2ef2bf5 is confirmed
End time: 2024-02-19 16:55:58
Total time: 17 seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 17.389 s
[INFO] Finished at: 2024-02-19T16:55:58-08:00
[INFO] ------------------------------------------------------------------------
Execute the following code in a terminal window to run the Chained Commerce use case code:
mvn exec:java -Dexec.mainClass="futuresdemo.ChainedCommerceProgram"You'll get output similar to the following:
Start time: 2024-02-19 16:54:48
Running a chained business process
Dispatcher started at 2024-02-19 16:54:48
Shipped: Order 6033774c-d34b-42e3-9575-3cf597dbfc9b, ended at 2024-02-19 16:54:49 and took 1 seconds
Order: 6033774c-d34b-42e3-9575-3cf597dbfc9b is pending
Payment started at 2024-02-19 16:54:49
Shipped: Order 6033774c-d34b-42e3-9575-3cf597dbfc9b, ended at 2024-02-19 16:54:51 and took 2 seconds
Order: 6033774c-d34b-42e3-9575-3cf597dbfc9b is paid at 2024-02-19 16:54:51
Shipper started at 2024-02-19 16:54:51
Shipped: Order 6033774c-d34b-42e3-9575-3cf597dbfc9b, ended at 2024-02-19 16:54:54 and took 3 seconds
Order: 6033774c-d34b-42e3-9575-3cf597dbfc9b is shipped at 2024-02-19 16:54:54
Delivery started at 2024-02-19 16:54:54
Shipped: Order 6033774c-d34b-42e3-9575-3cf597dbfc9b, ended at 2024-02-19 16:55:04 and took 10 seconds
Order: 6033774c-d34b-42e3-9575-3cf597dbfc9b is delivered at 2024-02-19 16:55:05
Confirmation started at 2024-02-19 16:55:05
Shipped: Order 6033774c-d34b-42e3-9575-3cf597dbfc9b, ended at 2024-02-19 16:55:06 and took 1 seconds
Order: 6033774c-d34b-42e3-9575-3cf597dbfc9b is confirmed at 2024-02-19 16:55:06
End time: 2024-02-19 16:55:06
Total time: 17 seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 17.495 s
[INFO] Finished at: 2024-02-19T16:55:06-08:00
[INFO] ------------------------------------------------------------------------