Implement Java Doublets Adapter via GraphQL client (Issue #14)

.github/workflows/java.yml

@@ -0,0 +1,51 @@
+name: Java CI
+
+on:
+  push:
+    paths:
+      - 'java/**'
+    branches: [ main, issue-14-b8e14d79 ]
+  pull_request:
+    paths:
+      - 'java/**'
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+
+    - name: Cache Maven packages
+      uses: actions/cache@v3
+      with:
+        path: ~/.m2
+        key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+        restore-keys: ${{ runner.os }}-m2
+
+    - name: Build with Maven
+      run: |
+        cd java
+        mvn clean compile
+
+    - name: Run tests
+      run: |
+        cd java
+        mvn test
+
+    - name: Package
+      run: |
+        cd java
+        mvn package -DskipTests
+
+    - name: Build examples
+      run: |
+        cd java/examples
+        mvn clean compile

README.md

@@ -189,3 +189,37 @@ mutation {
   }
 }
 ```
+
+## Java Implementation
+
+This repository now includes a complete Java implementation with three packages:
+
+1. **Platform.Data.Doublets.Client** - Abstract API for both GraphQL and native implementations
+2. **Platform.Data.Doublets.Gql.Client** - GraphQL client that connects to the server
+3. **Platform.Data.Doublets.Native** - Native library wrapper using JNI
+
+### Quick Start (Java)
+
+The Java implementation provides a clean, type-safe API that can swap between GraphQL and native backends:
+
+```java
+import platform.data.doublets.client.*;
+import platform.data.doublets.gql.client.GraphQLLinksClient;
+
+// Create GraphQL client
+LinksClient client = new GraphQLLinksClient("http://localhost:60341/v1/graphql");
+
+// Create a link
+Link link = client.getOrCreate(1L, 2L);
+
+// Search with query builder
+LinkQuery query = LinkQuery.builder()
+    .fromId(1L)
+    .limit(10)
+    .sortBy(LinkQuery.SortField.ID, LinkQuery.SortOrder.ASC)
+    .build();
+
+List<Link> results = client.searchLinks(query);
+```
+
+For detailed documentation and examples, see the [Java README](java/README.md).

java/README.md

@@ -0,0 +1,197 @@
+# Platform Data Doublets Java Implementation
+
+This is a Java implementation of Platform Data Doublets that provides three packages for different use cases:
+
+## Packages
+
+### 1. Platform.Data.Doublets.Client (platform-data-doublets-client)
+Abstract API that provides a standard interface for both GraphQL and native implementations.
+
+**Maven Dependency:**
+```xml
+<dependency>
+    <groupId>platform.data.doublets</groupId>
+    <artifactId>platform-data-doublets-client</artifactId>
+    <version>1.0.0</version>
+</dependency>
+```
+
+### 2. Platform.Data.Doublets.Gql.Client (platform-data-doublets-gql-client)
+GraphQL client implementation that connects to a Platform Data Doublets GraphQL server.
+
+**Maven Dependency:**
+```xml
+<dependency>
+    <groupId>platform.data.doublets</groupId>
+    <artifactId>platform-data-doublets-gql-client</artifactId>
+    <version>1.0.0</version>
+</dependency>
+```
+
+### 3. Platform.Data.Doublets.Native (platform-data-doublets-native)
+Native implementation that wraps the C++ library using JNI.
+
+**Maven Dependency:**
+```xml
+<dependency>
+    <groupId>platform.data.doublets</groupId>
+    <artifactId>platform-data-doublets-native</artifactId>
+    <version>1.0.0</version>
+</dependency>
+```
+
+## Usage Examples
+
+### Using the GraphQL Client
+
+```java
+import platform.data.doublets.client.*;
+import platform.data.doublets.gql.client.GraphQLLinksClient;
+
+public class GraphQLExample {
+    public static void main(String[] args) throws DoubletsException {
+        // Create GraphQL client
+        LinksClient client = new GraphQLLinksClient("http://localhost:8080/v1/graphql");
+
+        // Create a new link
+        Link link = client.getOrCreate(2L, 3L);
+        System.out.println("Created link: " + link);
+
+        // Search for links
+        LinkQuery query = LinkQuery.builder()
+                .fromId(2L)
+                .limit(10)
+                .sortBy(LinkQuery.SortField.ID, LinkQuery.SortOrder.ASC)
+                .build();
+
+        List<Link> links = client.searchLinks(query);
+        System.out.println("Found " + links.size() + " links");
+
+        // Get total count
+        long count = client.getLinksCount();
+        System.out.println("Total links: " + count);
+    }
+}
+```
+
+### Using the Native Client
+
+```java
+import platform.data.doublets.client.*;
+import platform.data.doublets.native.NativeLinksClient;
+
+public class NativeExample {
+    public static void main(String[] args) throws DoubletsException {
+        // Create native client
+        try (NativeLinksClient client = new NativeLinksClient("my-database.links")) {
+
+            // Create a new link
+            Link link = client.create(1L, 2L);
+            System.out.println("Created link: " + link);
+
+            // Update the link
+            Link updatedLink = client.update(link.getId(), 3L, 4L);
+            System.out.println("Updated link: " + updatedLink);
+
+            // Get all links
+            List<Link> allLinks = client.getAllLinks();
+            System.out.println("All links: " + allLinks);
+
+            // Delete the link
+            client.delete(link.getId());
+            System.out.println("Link deleted");
+
+        } // Client automatically closed here
+    }
+}
+```
+
+### Using the Abstract Interface
+
+```java
+import platform.data.doublets.client.*;
+import platform.data.doublets.gql.client.GraphQLLinksClient;
+import platform.data.doublets.native.NativeLinksClient;
+
+public class AbstractExample {
+    public static void demonstrateLinks(LinksClient client) throws DoubletsException {
+        // This method works with any implementation
+        Link link = client.getOrCreate(10L, 20L);
+
+        Optional<Link> retrieved = client.getLink(link.getId());
+        if (retrieved.isPresent()) {
+            System.out.println("Retrieved: " + retrieved.get());
+        }
+
+        List<Link> fromLinks = client.getLinksByFrom(10L);
+        System.out.println("Links from 10: " + fromLinks.size());
+    }
+
+    public static void main(String[] args) throws DoubletsException {
+        // Can switch implementations easily
+        LinksClient graphqlClient = new GraphQLLinksClient("http://localhost:8080/v1/graphql");
+        LinksClient nativeClient = new NativeLinksClient("db.links");
+
+        System.out.println("Using GraphQL client:");
+        demonstrateLinks(graphqlClient);
+
+        System.out.println("Using Native client:");
+        demonstrateLinks(nativeClient);
+    }
+}
+```
+
+## Building
+
+To build all packages:
+
+```bash
+cd java
+mvn clean install
+```
+
+To build a specific package:
+
+```bash
+cd java/platform-data-doublets-client
+mvn clean install
+```
+
+## Running Tests
+
+```bash
+cd java
+mvn test
+```
+
+## Architecture
+
+The architecture follows the dependency pattern described in the issue:
+
+```
+┌─────────────────────────┐    ┌─────────────────────────┐
+│  GraphQLLinksClient     │    │   NativeLinksClient     │
+│ (GraphQL implementation)│    │  (JNI implementation)   │
+└───────────┬─────────────┘    └───────────┬─────────────┘
+            │                              │
+            └──────────────┬───────────────┘
+                           │
+                           ▼
+                  ┌─────────────────┐
+                  │  LinksClient    │
+                  │ (Abstract API)  │
+                  └─────────────────┘
+```
+
+This design allows:
+- **Swappable implementations**: Easy to switch between GraphQL and native
+- **Testability**: Mock implementations can be created for testing
+- **Future extensibility**: New implementations can be added easily
+- **Separation of concerns**: GraphQL logic separate from native library concerns
+
+## Requirements
+
+- Java 17 or higher
+- Maven 3.6 or higher
+- For GraphQL client: Access to a Platform Data Doublets GraphQL server
+- For native client: Native library (platform-data-doublets-native.dll/so/dylib)

java/examples/pom.xml

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+<?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">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>platform.data.doublets</groupId>
+    <artifactId>platform-data-doublets-examples</artifactId>
+    <version>1.0.0</version>
+    <packaging>jar</packaging>
+
+    <name>Platform Data Doublets Examples</name>
+    <description>Usage examples for Platform Data Doublets Java packages</description>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>platform.data.doublets</groupId>
+            <artifactId>platform-data-doublets-client</artifactId>
+            <version>1.0.0</version>
+        </dependency>
+        <dependency>
+            <groupId>platform.data.doublets</groupId>
+            <artifactId>platform-data-doublets-gql-client</artifactId>
+            <version>1.0.0</version>
+        </dependency>
+        <dependency>
+            <groupId>platform.data.doublets</groupId>
+            <artifactId>platform-data-doublets-native</artifactId>
+            <version>1.0.0</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.11.0</version>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>