Add sample app for Pulsar Functions

See #135 #136

spring-pulsar-sample-apps/sample-pulsar-functions/sample-signup-function/build.gradle

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+plugins {
+	id 'java'
+}
+
+group = 'org.springframework.pulsar.sample'
+description = 'Sample Signup Pulsar Function'
+sourceCompatibility = '1.8'
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation 'org.apache.pulsar:pulsar-client-all:2.10.2'
+	implementation 'org.apache.pulsar:pulsar-functions-api:2.10.2'
+	compileOnly 'org.projectlombok:lombok:1.18.24'
+	annotationProcessor 'org.projectlombok:lombok:1.18.24'
+}
+
+// Customization of jar to make a simple Uber function jar
+jar {
+	manifest {
+		attributes 'Main-Class': 'org.springframework.pulsar.sample.signup.SignupFunction'
+	}
+	duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+	from sourceSets.main.output
+	dependsOn configurations.runtimeClasspath
+	from(configurations.runtimeClasspath.findAll { it.name.endsWith('jar') }.collect { zipTree(it) }) {
+		exclude 'META-INF/*.RSA', 'META-INF/*.SF', 'META-INF/*.DSA'
+	}
+}

spring-pulsar-sample-apps/sample-pulsar-functions/sample-signup-function/src/main/java/org.springframework.pulsar.sample.signup/SignupFunction.java

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+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.pulsar.sample.signup;
+
+import org.apache.pulsar.client.api.PulsarClientException;
+import org.apache.pulsar.client.api.Schema;
+import org.apache.pulsar.functions.api.Context;
+import org.apache.pulsar.functions.api.Function;
+
+import org.springframework.pulsar.sample.signup.model.Customer;
+import org.springframework.pulsar.sample.signup.model.Signup;
+import org.springframework.pulsar.sample.signup.model.SignupTier;
+
+public class SignupFunction implements Function<Signup, Void> {
+
+	@Override
+	public Void process(Signup signup, Context context) {
+		log("Processing " + signup);
+
+		// Count and log the signups for tier
+		SignupTier tier = signup.getSignupTier();
+		context.incrCounter(tier.name(), 1L);
+		long count = context.getCounter(tier.name());
+		log(String.format("   %s signup count: %d", tier.name(), count));
+
+		// Create customer onboard for enterprise signups
+		if (tier == SignupTier.ENTERPRISE) {
+			Customer customer = Customer.from(signup);
+			log("Converting to " + signup);
+			try {
+				context.newOutputMessage("customer-onboard", Schema.JSON(Customer.class))
+						.key(customer.getEmail())
+						.value(customer)
+						.eventTime(System.currentTimeMillis())
+						.send();
+			} catch (PulsarClientException e) {
+				e.printStackTrace();
+				throw new RuntimeException(e.getMessage(), e);
+			}
+		}
+		return null;
+	}
+
+	private void log(String msg) {
+		// Typically logging is done via context.getLogger() but that logs to a topic
+		// which is not helpful during dev/debugging - sending to console for that reason
+		System.out.println(msg);
+	}
+}

spring-pulsar-sample-apps/sample-pulsar-functions/sample-signup-function/src/main/java/org.springframework.pulsar.sample.signup/model/Customer.java

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+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.pulsar.sample.signup.model;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class Customer {
+
+	private String firstName;
+
+	private String lastName;
+
+	private String email;
+
+	private long signupTimestamp;
+
+	public static Customer from(Signup signup) {
+		return new Customer(
+				signup.getFirstName(),
+				signup.getLastName(),
+				signup.getEmail(),
+				signup.getSignupTimestamp());
+	}
+}

spring-pulsar-sample-apps/sample-pulsar-functions/sample-signup-function/src/main/java/org.springframework.pulsar.sample.signup/model/Signup.java

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+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.pulsar.sample.signup.model;
+
+import lombok.Data;
+
+@Data
+public class Signup {
+
+	private SignupTier signupTier;
+
+	private String firstName;
+
+	private String lastName;
+
+	private String email;
+
+	private long signupTimestamp;
+}

spring-pulsar-sample-apps/sample-pulsar-functions/sample-signup-function/src/main/java/org.springframework.pulsar.sample.signup/model/SignupTier.java

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+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.pulsar.sample.signup.model;
+
+public enum SignupTier {
+  FREE,
+  BASIC,
+  STANDARD,
+  ENTERPRISE
+}