logging and README

README.md

@@ -5,17 +5,44 @@
 [![sponsored](https://img.shields.io/badge/sponsoredBy-Holisticon-RED.svg)](https://holisticon.de/)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/io.holixon.example.axon-event-transformation/axon-event-transformation-example/badge.svg)](https://maven-badges.herokuapp.com/maven-central/io.holixon.example.axon-event-transformation/axon-event-transformation-example)
 
+## Into
+
+The example demonstrates the usage of the event store transformation API and focuses on deletion of "stale" events.
+
+## Use case
+
+Consider a system storing temperature forecast delivered by some external system. The forecast is generated periodically and the system is representing the actual forecast.
+Apart from the historical information (which can be for example used to tune the forecast model), the system holds current (= latest) forecast and can be queried for the 
+weather on a certain date. After the delivery of the new forecast, the previous forecast is considered as "stale" and doesn't need to be stored.
+
+## The API
+
+The system allows to insert a new temperature value at a single date and query temperature on certain date. For *simulation purposes* the system provides a fake endpoint
+for generation of an entire forecast for the next year (taking random values for the temperature).
+
+## The mission
+
+Try to use event store transformation API to delete stale events and reduce the size of the event store - both for purposes of disk usage and the amount of events used on replays.
+
 ## Experiment
 
+- A sensor is created (1 event)
+- The first batch of 365 updates (starting from today for the next year) for 365 days from update date to the future is sent
+- The second batch of 365 updates (starting from today for the next year) for 365 days from update date to the future is sent
+- All 365 events from the first batch are deleted 
+
+### Preparation
+
+- Axon server is configured to use small segments. Size of event file set to 1000000 bytes (977kb).
+
 ### Setup
 
-- Size of event file set to 1000000 bytes (977kb).
 - We consider only event storage (no snapshot files, no nindex files, no global-index-00000.xref)
-- The size of the snapshot file can be set-up via property
+- The size of the snapshot file can be set-up via property separately.
 - The size of the index file seems to be 2097152 bytes (approx 2mb) for event segment files of default size (256mb) and for a drastically reduced event segment size of 977k.
-- The size of global-index-00000.xref is 64mb
-
-Event payload:
+- The size of global-index-00000.xref is 64mb.
+- Events use Jackson serializer storing payload as JSON.
+- Event payload is then represented like this:
 
 ```json
 {
@@ -29,12 +56,13 @@ Event payload:
       "value": 23.188648,
       "unit": "°C"
     },
+    ...
     another 363 values for dates
   }
 }
 ```
-A single JSON payload consumes 16415 bytes in total (netto)
-Based on file names of event files (00000000000000000175.events, 00000000000000000233.events) 58 update events match into a 977kb file resulting in 16845 bytes (brutto).
+- A single JSON payload consumes 16415 bytes in total (netto).
+- Based on file names of event files (00000000000000000175.events, 00000000000000000233.events) 58 update events match into a 977kb file resulting in 16845 bytes (brutto).
 
 356 event consume 16845 * 365 = 6148425 brutto (splitting), resulting in not quite full 7 segments per batch run.
 
@@ -107,3 +135,14 @@ Based on file names of event files (00000000000000000175.events, 000000000000000
 977K Jan 17 22:48 00000000000000000639.events
 977K Jan 17 22:48 00000000000000000697.events
 
+## How to run
+
+- Start Axon Server via `docker-compose up`
+- Build application with mvn (`./mvnw clean package`)
+- Start application `java -jar target/axon-event-transformation-example-0.0.1-SNAPSHOT.jar` and check the console [Admin console](http://localhost:8024)
+- Open browser and navigate to [Swagger UI](http://localhost:8080/swagger-ui/index.html)
+- Run a batch update (HTTP POST to `/measurements/batch`) and check files in `.docker/events/default`  
+- Run a batch update for the second time (HTTP POST to `/measurements/batch`) and check files in `.docker/events/default`
+- Copy the `start` value of from the HTTP response of the second batch run
+- Run cleanup, by providing the value from the previous step as a string payload (HTTP POST to `/admin/cleanup`) and check files in `.docker/events/default`
+- Run compact (HTTP POST to `/admin/compact`) and check files in `.docker/events/default`

pom.xml

@@ -20,14 +20,15 @@
     <!-- TEST -->
     <mockito.version>5.2.1</mockito.version>
     <assertj.version>3.24.2</assertj.version>
+    <spring-boot.version>3.1.2</spring-boot.version>
   </properties>
 
   <dependencyManagement>
     <dependencies>
       <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-dependencies</artifactId>
-        <version>3.1.2</version>
+        <version>${spring-boot.version}</version>
         <scope>import</scope>
         <type>pom</type>
       </dependency>
@@ -139,6 +140,19 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-enforcer-plugin</artifactId>
       </plugin>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+        <version>${spring-boot.version}</version>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>repackage</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 

src/main/kotlin/SensorApplication.kt

@@ -4,6 +4,7 @@ import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
 
 fun main(args: Array<String>) {
+  System.setProperty("disable-axoniq-console-message", "true")
   runApplication<SensorApplication>(*args).let { Unit }
 }
 

src/main/kotlin/application/usecase/GenerateRandomBatchUpdateUseCase.kt

@@ -4,7 +4,9 @@ import io.holixon.example.axon.event.transformation.application.port.`in`.Genera
 import io.holixon.example.axon.event.transformation.application.port.`in`.Measurement
 import io.holixon.example.axon.event.transformation.application.port.`in`.SensorMeasurements
 import io.holixon.example.axon.event.transformation.application.port.`in`.UpdateMeasurementInPort
+import mu.KLogging
 import org.springframework.stereotype.Component
+import java.time.Instant
 import java.time.LocalDate
 import kotlin.random.Random
 
@@ -13,11 +15,15 @@ class GenerateRandomBatchUpdateUseCase(
   val updateMeasurementInPort: UpdateMeasurementInPort
 ) : GenerateRandomBatchUpdateInPort {
 
+  companion object: KLogging()
+
   override fun runBatchUpdate(sensorId: String) {
+    logger.info { "Starting update batch..." }
     (0L..365L).forEach { offset ->
       val updateDate = LocalDate.now().plusDays(offset)
       generateForecast(sensorId, updateDate)
     }
+    logger.info { "Batch update complete." }
   }
 
   fun generateForecast(sensorId: String, updateDate: LocalDate) {

src/main/kotlin/infrastructure/EventCleanup.kt

@@ -22,6 +22,7 @@ class EventCleanup(
   companion object : KLogging()
 
   fun deleteEventsUntil(eventFQDN: String, deleteUntil: Instant, firstToken: Long = 0, lastToken: Long = -1L) {
+    logger.info { "Deleting all events of type $eventFQDN older than $deleteUntil..." }
     AutoClosableAxonServerConnection
       .connect(connect.hostName, connect.grpcPort, this.javaClass.simpleName, this.context).use { connection ->
 
@@ -50,9 +51,11 @@ class EventCleanup(
           connection.ensureNoActiveTransformations()
         }
       }
+    logger.info { "Deleting complete." }
   }
 
   fun compact() {
+    logger.info { "Compacting event store..." }
     AutoClosableAxonServerConnection
       .connect(connect.hostName, connect.grpcPort, this.javaClass.simpleName, this.context).use { connection ->
         connection.ensureNoActiveTransformations()
@@ -61,6 +64,7 @@ class EventCleanup(
           .startCompacting()
           .get()
       }
+    logger.info { "Compacting complete." }
   }
 
   fun AxonServerConnection.ensureNoActiveTransformations() {