Getting Started with ScalarDB Cluster SQL via Spring Data JDBC for ScalarDB
This tutorial describes how to create a sample application by using ScalarDB Cluster SQL via Spring Data JDBC for ScalarDB.
Prerequisites for this sample application
- One of the following Java Development Kits (JDKs):
- Oracle JDK 8
- OpenJDK 8 from Eclipse Temurin, Amazon Corretto, or Microsoft
- ScalarDB Cluster running on a Kubernetes cluster
- We assume that you have a ScalarDB Cluster running on a Kubernetes cluster that you deployed by following the instructions in Set Up ScalarDB Cluster on Kubernetes by Using a Helm Chart.
This sample application only works with Java 8. However, ScalarDB itself works with Java LTS versions, which means that you can use Java LTS versions for your application that uses ScalarDB. For details on the requirements of ScalarDB, such as which Java versions can be used, see Requirements.
Sample application
This tutorial illustrates the process of creating a sample e-commerce application, where items can be ordered and paid for with a line of credit by using Spring Data JDBC for ScalarDB.
The following diagram shows the system architecture of the sample application:
+------------------------------------------------------------------------------------------------------------------------------+
| [Kubernetes Cluster] |
| |
| [Pod] [Pod] [Pod] |
+------------------------+ | |
| SQL CLI | | +-------+ +-----------------------+ |
| (indirect client mode) | --+ | +---> | Envoy | ---+ +---> | ScalarDB Cluster Node | ---+ |
+------------------------+ | | | +-------+ | | +-----------------------+ | |
| | | | | | |
| | +---------+ | +-------+ | +--------------------+ | +-----------------------+ | +------------+ |
+--+-> | Service | ---+---> | Envoy | ---+---> | Service | ---+---> | ScalarDB Cluster Node | ---+---> | PostgreSQL | |
+------------------------+ | | | (Envoy) | | +-------+ | | (ScalarDB Cluster) | | +-----------------------+ | +------------+ |
| Sample application | | | +---------+ | | +--------------------+ | | |
| with Spring Data JDBC | | | | +-------+ | | +-----------------------+ | |
| for ScalarDB | --+ | +---> | Envoy | ---+ +---> | ScalarDB Cluster Node | ---+ |
| (indirect client mode) | | +-------+ +-----------------------+ |
+------------------------+ | |
+------------------------------------------------------------------------------------------------------------------------------+
Step 1. Clone the ScalarDB Samples repository
git clone https://github.com/scalar-labs/scalardb-samples.git
cd scalardb-samples/spring-data-sample
Step 2. Modify scalardb-sql.properties
You need to modify scalardb-sql.properties
to connect to ScalarDB Cluster as well.
But before doing so, you need to get the EXTERNAL-IP
address of the service resource of Envoy (scalardb-cluster-envoy
) as follows:
kubectl get svc scalardb-cluster-envoy
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
scalardb-cluster-envoy LoadBalancer 10.105.121.51 localhost 60053:30641/TCP 16h
In this case, the EXTERNAL-IP
address is localhost
.
Next, open scalardb-sql.properties
:
vim scalardb-sql.properties
Then, modify scalardb-sql.properties
as follows:
scalar.db.sql.connection_mode=cluster
scalar.db.sql.cluster_mode.contact_points=indirect:localhost
To connect to ScalarDB Cluster, you need to specify cluster
for the scalar.db.sql.connection_mode
property.
In addition, you will use the indirect
client mode and connect to the service resource of Envoy in this tutorial.
For details about the client modes, see Developer Guide for ScalarDB Cluster with the Java API.
Step 3. Load a schema
To load a schema, you need to use the SQL CLI. You can download the SQL CLI from ScalarDB Releases. After downloading the JAR file, you can use SQL CLI for Cluster by running the following command:
java -jar scalardb-cluster-sql-cli-3.12.3-all.jar --config scalardb-sql.properties --file schema.sql
Step 4. Modify application.properties
Then, you need to modify application.properties
to connect to ScalarDB Cluster as well:
vim src/main/resources/application.properties
Similar to scalardb-sql.properties
, you need to specify cluster
for the scalar.db.sql.connection_mode
property and use the indirect
client mode.
To do so, modify application.properties
as follows:
spring.datasource.driver-class-name=com.scalar.db.sql.jdbc.SqlJdbcDriver
spring.datasource.url=jdbc:scalardb:\
?scalar.db.sql.connection_mode=cluster\
&scalar.db.sql.cluster_mode.contact_points=indirect:localhost\
&scalar.db.consensus_commit.isolation_level=SERIALIZABLE\
&scalar.db.sql.default_namespace_name=sample
Step 5. Load the initial data
Before running the sample application, you need to load the initial data by running the following command:
./gradlew run --args="LoadInitialData"
After the initial data has loaded, the following records should be stored in the tables:
- For the
sample.customers
table:
customer_id | name | credit_limit | credit_total |
---|---|---|---|
1 | Yamada Taro | 10000 | 0 |
2 | Yamada Hanako | 10000 | 0 |
3 | Suzuki Ichiro | 10000 | 0 |
- For the
sample.items
table:
item_id | name | price |
---|---|---|
1 | Apple | 1000 |
2 | Orange | 2000 |
3 | Grape | 2500 |
4 | Mango | 5000 |
5 | Melon | 3000 |
Step 6. Run the sample application
Let's start with getting information about the customer whose ID is 1
:
./gradlew run --args="GetCustomerInfo 1"
...
{"customer_id":1,"name":"Yamada Taro","credit_limit":10000,"credit_total":0}
...
Then, place an order for three apples and two oranges by using customer ID 1
. Note that the order format is <Item ID>:<Count>,<Item ID>:<Count>,...
:
./gradlew run --args="PlaceOrder 1 1:3,2:2"
...
{"order_id":"2358ab35-5819-4f8f-acb1-12e73d97d34e","customer_id":1,"timestamp":1677478005400}
...
You can see that running this command shows the order ID.
Let's check the details of the order by using the order ID:
./gradlew run --args="GetOrder 2358ab35-5819-4f8f-acb1-12e73d97d34e"
...
{"order_id":"2358ab35-5819-4f8f-acb1-12e73d97d34e","timestamp":1677478005400,"customer_id":1,"customer_name":"Yamada Taro","statements":[{"item_id":1,"item_name":"Apple","price":1000,"count":3,"total":3000},{"item_id":2,"item_name":"Orange","price":2000,"count":2,"total":4000}],"total":7000}
...
Then, let's place another order and get the order history of customer ID 1
:
./gradlew run --args="PlaceOrder 1 5:1"
...
{"order_id":"46062b16-b71b-46f9-a9ff-dc6b0991259b","customer_id":1,"timestamp":1677478201428}
...
./gradlew run --args="GetOrders 1"
...
[{"order_id":"46062b16-b71b-46f9-a9ff-dc6b0991259b","timestamp":1677478201428,"customer_id":1,"customer_name":"Yamada Taro","statements":[{"item_id":5,"item_name":"Melon","price":3000,"count":1,"total":3000}],"total":3000},{"order_id":"2358ab35-5819-4f8f-acb1-12e73d97d34e","timestamp":1677478005400,"customer_id":1,"customer_name":"Yamada Taro","statements":[{"item_id":1,"item_name":"Apple","price":1000,"count":3,"total":3000},{"item_id":2,"item_name":"Orange","price":2000,"count":2,"total":4000}],"total":7000}]
...
This order history is shown in descending order by timestamp.
The customer's current credit_total
is 10000
. Since the customer has now reached their credit_limit
, which was shown when retrieving their information, they cannot place anymore orders.
./gradlew run --args="GetCustomerInfo 1"
...
{"id": 1, "name": "Yamada Taro", "credit_limit": 10000, "credit_total": 10000}
...
./gradlew run --args="PlaceOrder 1 3:1,4:1"
...
java.lang.RuntimeException: Credit limit exceeded. limit:10000, total:17500
at sample.SampleService.placeOrder(SampleService.java:102)
at sample.SampleService$$FastClassBySpringCGLIB$$1123c447.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:793)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708)
at sample.SampleService$$EnhancerBySpringCGLIB$$a94e1d9.placeOrder(<generated>)
at sample.command.PlaceOrderCommand.call(PlaceOrderCommand.java:37)
at sample.command.PlaceOrderCommand.call(PlaceOrderCommand.java:13)
at picocli.CommandLine.executeUserObject(CommandLine.java:2041)
at picocli.CommandLine.access$1500(CommandLine.java:148)
at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2461)
at picocli.CommandLine$RunLast.handle(CommandLine.java:2453)
at picocli.CommandLine$RunLast.handle(CommandLine.java:2415)
at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2273)
at picocli.CommandLine$RunLast.execute(CommandLine.java:2417)
at picocli.CommandLine.execute(CommandLine.java:2170)
at sample.SampleApp.run(SampleApp.java:26)
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:768)
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:752)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1303)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292)
at sample.SampleApp.main(SampleApp.java:35)
...
After making a payment, the customer will be able to place orders again.
./gradlew run --args="Repayment 1 8000"
...
./gradlew run --args="GetCustomerInfo 1"
...
{"customer_id":1,"name":"Yamada Taro","credit_limit":10000,"credit_total":2000}
...
./gradlew run --args="PlaceOrder 1 3:1,4:1"
...
{"order_id":"0350947a-9003-46f2-870e-6aa4b2df0f1f","customer_id":1,"timestamp":1677478728134}
...
Source code of the sample application
To learn more about Spring Data JDBC for ScalarDB, you can check the source code of the sample application.
See also
For other ScalarDB Cluster tutorials, see the following:
- Getting Started with ScalarDB Cluster
- Getting Started with ScalarDB Cluster GraphQL
- Getting Started with ScalarDB Cluster SQL via JDBC
- Getting Started with Using Go for ScalarDB Cluster
- Getting Started with Using Python for ScalarDB Cluster
For details about developing applications that use ScalarDB Cluster with the Java API, refer to the following:
For details about the ScalarDB Cluster gRPC API, refer to the following: