Add basic message classes and JsonObject utils

messaging/messaging-core/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>messaging</artifactId>
+        <groupId>uk.gov.justice.services</groupId>
+        <version>0.1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>messaging-core</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>javax.json</groupId>
+            <artifactId>javax.json-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-library</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.glassfish</groupId>
+            <artifactId>javax.json</artifactId>
+            <version>1.0.4</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>net.trajano.commons</groupId>
+            <artifactId>commons-testing</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+</project>

messaging/messaging-core/src/main/java/uk/gov/justice/services/messaging/DefaultEnvelope.java

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+package uk.gov.justice.services.messaging;
+
+import javax.json.JsonObject;
+
+/**
+ * Default implementation of an envelope.
+ */
+public class DefaultEnvelope implements Envelope {
+
+    private Metadata metadata;
+
+    private JsonObject payload;
+
+    private DefaultEnvelope(final Metadata metadata, final JsonObject payload) {
+        this.metadata = metadata;
+        this.payload = payload;
+    }
+
+    @Override
+    public Metadata metadata() {
+        return metadata;
+    }
+
+    @Override
+    public JsonObject payload() {
+        return payload;
+    }
+
+    public static Envelope envelopeFrom(final Metadata metadata, final JsonObject payload) {
+        return new DefaultEnvelope(metadata, payload);
+    }
+}

messaging/messaging-core/src/main/java/uk/gov/justice/services/messaging/Envelope.java

@@ -0,0 +1,13 @@
+package uk.gov.justice.services.messaging;
+
+import javax.json.JsonObject;
+
+/**
+ * Interface for a messaging envelope containing metadata and a payload.
+ */
+public interface Envelope {
+
+    Metadata metadata();
+
+    JsonObject payload();
+}

messaging/messaging-core/src/main/java/uk/gov/justice/services/messaging/JsonObjectMetadata.java

@@ -0,0 +1,93 @@
+package uk.gov.justice.services.messaging;
+
+import javax.json.JsonObject;
+import javax.json.JsonString;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+
+import static uk.gov.justice.services.messaging.JsonObjects.getJsonString;
+import static uk.gov.justice.services.messaging.JsonObjects.getLong;
+import static uk.gov.justice.services.messaging.JsonObjects.getString;
+import static uk.gov.justice.services.messaging.JsonObjects.getUUID;
+import static uk.gov.justice.services.messaging.JsonObjects.getUUIDs;
+
+/**
+ * Implementation of metadata that uses a JsonObject internally to store the metadata.
+ */
+public class JsonObjectMetadata implements Metadata {
+
+    private final JsonObject metadata;
+
+    private JsonObjectMetadata(final JsonObject metadata) {
+        this.metadata = metadata;
+    }
+
+    @Override
+    public UUID id() {
+        return getUUID(metadata, ID)
+                .orElseThrow(() -> new IllegalStateException("Missing id field"));
+    }
+
+    @Override
+    public String name() {
+        return getString(metadata, NAME)
+                .orElseThrow(() -> new IllegalStateException("Missing name field"));
+    }
+
+    @Override
+    public Optional<String> clientCorrelationId() {
+        return getString(metadata, CLIENT_CORRELATION);
+    }
+
+    @Override
+    public List<UUID> causation() {
+        return getUUIDs(metadata, CAUSATION);
+    }
+
+    @Override
+    public Optional<String> userId() {
+        return getString(metadata, USER_ID);
+    }
+
+    @Override
+    public Optional<String> sessionId() {
+        return getString(metadata, SESSION_ID);
+    }
+
+    @Override
+    public Optional<UUID> streamId() {
+        return getUUID(metadata, STREAM_ID);
+    }
+
+    @Override
+    public Optional<Long> version() {
+        return getLong(metadata, VERSION);
+    }
+
+    @Override
+    public JsonObject asJsonObject() {
+        return metadata;
+    }
+
+    /**
+     * Instantiate a {@link JsonObjectMetadata} object from a {@link JsonObject}.
+     *
+     * @param jsonObject the {@link JsonObject} to build the metadata from
+     * @return the {@link JsonObjectMetadata}
+     */
+    public static Metadata metadataFrom(final JsonObject jsonObject) {
+
+        JsonString id = getJsonString(jsonObject, Metadata.ID)
+                .orElseThrow(() -> new IllegalArgumentException("Missing id field"));
+        UUID.fromString(id.getString());
+
+        JsonString name = getJsonString(jsonObject, Metadata.NAME)
+                .orElseThrow(() -> new IllegalArgumentException("Missing name field"));
+        if (name.getString().isEmpty()) {
+            throw new IllegalArgumentException("Name field cannot be empty");
+        }
+
+        return new JsonObjectMetadata(jsonObject);
+    }
+}