feat(java,info): refactor yaml saver api

docs/libraries/java/info/getting-started.md

@@ -96,6 +96,66 @@ MyStringGraphInfoLoader customLoader = new MyStringGraphInfoLoader();
 GraphInfo graphInfo = customLoader.loadGraphInfo(URI.create("db://mydatabase/graphs/graph1/graph.yml"));
 ```
 
+### Save Graph Info
+
+The java-info module also provides functionality to save graph metadata to YAML files using the `GraphSaver` interface. Here's an example of how to use it:
+
+```java
+import org.apache.graphar.info.GraphInfo;
+import org.apache.graphar.info.saver.GraphInfoSaver;
+import org.apache.graphar.info.saver.impl.LocalFileSystemYamlGraphSaver;
+import java.net.URI;
+
+// Create or obtain a GraphInfo object
+GraphInfo graphInfo = createOrLoadGraphInfo(); // your method to create or load GraphInfo
+
+// Create a GraphSaver instance
+GraphInfoSaver graphSaver = new LocalFileSystemYamlGraphSaver();
+
+// Save the graph info to a directory
+String savePath = "/path/to/save/directory";
+try {
+    graphSaver.save(URI.create(savePath), graphInfo);
+    System.out.println("Graph info saved successfully to " + savePath);
+} catch (IOException e) {
+    System.err.println("Failed to save graph info: " + e.getMessage());
+    e.printStackTrace();
+}
+```
+
+This will save the graph metadata as a set of YAML files:
+- One main graph YAML file (e.g., `graph-name.graph.yaml`)
+- One YAML file for each vertex type (e.g., `person.vertex.yaml`)
+- One YAML file for each edge type (e.g., `person_knows_person.edge.yaml`)
+
+Alternatively, you can use the dump method to convert graph info to a string and store it anywhere:
+
+```java
+import org.apache.graphar.info.GraphInfo;
+import org.apache.graphar.info.EdgeInfo;
+import org.apache.graphar.info.VertexInfo;
+import java.net.URI;
+
+// Create or obtain a GraphInfo object
+GraphInfo graphInfo = createOrLoadGraphInfo(); // your method to create or load GraphInfo
+
+// Set custom storage URIs for vertex and edge info files
+for (VertexInfo vertexInfo : graphInfo.getVertexInfos()) {
+    graphInfo.setStoreUri(vertexInfo, URI.create("db://path/vertex/" + vertexInfo.getType() + ".vertex.yaml"));
+}
+
+for (EdgeInfo edgeInfo : graphInfo.getEdgeInfos()) {
+    graphInfo.setStoreUri(edgeInfo, URI.create("db://path/edge/" + edgeInfo.getConcat() + ".edge.yaml"));
+}
+
+// Convert graph info to YAML string
+String graphYamlString = graphInfo.dump();
+
+// Now you can store the YAML string anywhere you want
+// For example, save to a database, send over network, etc.
+saveYamlStringToDatabase(graphYamlString);
+```
+
 ### Building
 
 To build the graphar-info module, you need:

maven-projects/info/src/main/java/org/apache/graphar/info/GraphInfo.java

@@ -20,9 +20,7 @@
 package org.apache.graphar.info;
 
 import java.net.URI;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
+import java.util.*;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -37,6 +35,23 @@ public class GraphInfo {
     private final Map<String, VertexInfo> vertexType2VertexInfo;
     private final Map<String, EdgeInfo> edgeConcat2EdgeInfo;
     private final VersionInfo version;
+    private final Map<String, URI> types2StoreUri;
+
+    public GraphInfo(
+            String name,
+            Map<URI, VertexInfo> vertexInfos,
+            Map<URI, EdgeInfo> edgeInfos,
+            URI uri,
+            String version) {
+        this(
+                name,
+                new ArrayList<>(vertexInfos.values()),
+                new ArrayList<>(edgeInfos.values()),
+                uri,
+                version);
+        vertexInfos.forEach((key, value) -> types2StoreUri.put(value.getType() + ".vertex", key));
+        edgeInfos.forEach((key, value) -> types2StoreUri.put(value.getConcat() + ".edge", key));
+    }
 
     public GraphInfo(
             String name,
@@ -68,6 +83,7 @@ public GraphInfo(
                         .collect(
                                 Collectors.toUnmodifiableMap(
                                         EdgeInfo::getConcat, Function.identity()));
+        this.types2StoreUri = new HashMap<>();
     }
 
     private GraphInfo(
@@ -103,6 +119,13 @@ private GraphInfo(
         this.version = version;
         this.vertexType2VertexInfo = vertexType2VertexInfo;
         this.edgeConcat2EdgeInfo = edgeConcat2EdgeInfo;
+        this.types2StoreUri = new HashMap<>();
+    }
+
+    public String dump(URI storeUri) {
+        Yaml yaml = new Yaml(GraphYaml.getRepresenter(), GraphYaml.getDumperOptions());
+        GraphYaml graphYaml = new GraphYaml(storeUri, this);
+        return yaml.dump(graphYaml);
     }
 
     public String dump() {
@@ -212,6 +235,34 @@ public VersionInfo getVersion() {
         return version;
     }
 
+    public void setStoreUri(VertexInfo vertexInfo, URI storeUri) {
+        this.types2StoreUri.put(vertexInfo.getType() + ".vertex", storeUri);
+    }
+
+    public void setStoreUri(EdgeInfo edgeInfo, URI storeUri) {
+        this.types2StoreUri.put(edgeInfo.getConcat() + ".edge", storeUri);
+    }
+
+    public URI getStoreUri(VertexInfo vertexInfo) {
+        String type = vertexInfo.getType() + ".vertex";
+        if (types2StoreUri.containsKey(type)) {
+            return types2StoreUri.get(type);
+        }
+        return URI.create(type + ".yaml");
+    }
+
+    public URI getStoreUri(EdgeInfo edgeInfo) {
+        String type = edgeInfo.getConcat() + ".edge";
+        if (types2StoreUri.containsKey(type)) {
+            return types2StoreUri.get(type);
+        }
+        return URI.create(type + ".yaml");
+    }
+
+    public Map<String, URI> getTypes2Uri() {
+        return types2StoreUri;
+    }
+
     private void checkVertexExist(String type) {
         if (!hasVertexInfo(type)) {
             throw new IllegalArgumentException(

maven-projects/info/src/main/java/org/apache/graphar/info/loader/BaseGraphInfoLoader.java

@@ -21,8 +21,8 @@
 
 import java.io.IOException;
 import java.net.URI;
-import java.util.ArrayList;
-import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
 import java.util.stream.Collectors;
 import org.apache.graphar.info.EdgeInfo;
 import org.apache.graphar.info.GraphInfo;
@@ -41,7 +41,7 @@ public abstract class BaseGraphInfoLoader implements GraphInfoLoader {
 
     public abstract EdgeInfo loadEdgeInfo(URI edgeYamlUri) throws IOException;
 
-    public GraphInfo buildGraphInfoFromGraphYaml(URI baseUri, GraphYaml graphYaml)
+    protected GraphInfo buildGraphInfoFromGraphYaml(URI baseUri, GraphYaml graphYaml)
             throws IOException {
 
         URI defaultBaseUri = baseUri.resolve(".");
@@ -50,16 +50,16 @@ public GraphInfo buildGraphInfoFromGraphYaml(URI baseUri, GraphYaml graphYaml)
         }
 
         // load vertices
-        List<VertexInfo> vertexInfos = new ArrayList<>(graphYaml.getVertices().size());
+        Map<URI, VertexInfo> vertexInfos = new TreeMap<>();
         for (String vertexYamlPath : graphYaml.getVertices()) {
             URI vertexInfoUri = baseUri.resolve(vertexYamlPath);
-            vertexInfos.add(loadVertexInfo(vertexInfoUri));
+            vertexInfos.put(vertexInfoUri, loadVertexInfo(vertexInfoUri));
         }
         // load edges
-        List<EdgeInfo> edgeInfos = new ArrayList<>(graphYaml.getEdges().size());
+        Map<URI, EdgeInfo> edgeInfos = new TreeMap<>();
         for (String edgeYamlPath : graphYaml.getEdges()) {
             URI edgeInfoUri = baseUri.resolve(edgeYamlPath);
-            edgeInfos.add(loadEdgeInfo(edgeInfoUri));
+            edgeInfos.put(edgeInfoUri, loadEdgeInfo(edgeInfoUri));
         }
         return new GraphInfo(
                 graphYaml.getName(),
@@ -69,7 +69,7 @@ public GraphInfo buildGraphInfoFromGraphYaml(URI baseUri, GraphYaml graphYaml)
                 graphYaml.getVersion());
     }
 
-    public VertexInfo buildVertexInfoFromGraphYaml(VertexYaml vertexYaml) {
+    protected VertexInfo buildVertexInfoFromVertexYaml(VertexYaml vertexYaml) {
         return new VertexInfo(
                 vertexYaml.getType(),
                 vertexYaml.getChunk_size(),
@@ -80,7 +80,7 @@ public VertexInfo buildVertexInfoFromGraphYaml(VertexYaml vertexYaml) {
                 vertexYaml.getVersion());
     }
 
-    public EdgeInfo buildEdgeInfoFromGraphYaml(EdgeYaml edgeYaml) {
+    protected EdgeInfo buildEdgeInfoFromEdgeYaml(EdgeYaml edgeYaml) {
         return new EdgeInfo(
                 edgeYaml.getSrc_type(),
                 edgeYaml.getEdge_type(),

maven-projects/info/src/main/java/org/apache/graphar/info/loader/ReaderGraphInfoLoader.java

@@ -49,14 +49,14 @@ public VertexInfo loadVertexInfo(URI vertexYamlUri) throws IOException {
         Reader yaml = readYaml(vertexYamlUri);
         Yaml vertexYamlLoader = new Yaml(new Constructor(VertexYaml.class, new LoaderOptions()));
         VertexYaml vertexYaml = vertexYamlLoader.load(yaml);
-        return buildVertexInfoFromGraphYaml(vertexYaml);
+        return buildVertexInfoFromVertexYaml(vertexYaml);
     }
 
     @Override
     public EdgeInfo loadEdgeInfo(URI edgeYamlUri) throws IOException {
         Reader yaml = readYaml(edgeYamlUri);
         Yaml edgeYamlLoader = new Yaml(new Constructor(EdgeYaml.class, new LoaderOptions()));
         EdgeYaml edgeYaml = edgeYamlLoader.load(yaml);
-        return buildEdgeInfoFromGraphYaml(edgeYaml);
+        return buildEdgeInfoFromEdgeYaml(edgeYaml);
     }
 }

maven-projects/info/src/main/java/org/apache/graphar/info/loader/StreamGraphInfoLoader.java

@@ -50,14 +50,14 @@ public VertexInfo loadVertexInfo(URI vertexYamlUri) throws IOException {
         InputStream yaml = readYaml(vertexYamlUri);
         Yaml edgeYamlLoader = new Yaml(new Constructor(VertexYaml.class, new LoaderOptions()));
         VertexYaml edgeYaml = edgeYamlLoader.load(yaml);
-        return buildVertexInfoFromGraphYaml(edgeYaml);
+        return buildVertexInfoFromVertexYaml(edgeYaml);
     }
 
     @Override
     public EdgeInfo loadEdgeInfo(URI edgeYamlUri) throws IOException {
         InputStream yaml = readYaml(edgeYamlUri);
         Yaml edgeYamlLoader = new Yaml(new Constructor(EdgeYaml.class, new LoaderOptions()));
         EdgeYaml edgeYaml = edgeYamlLoader.load(yaml);
-        return buildEdgeInfoFromGraphYaml(edgeYaml);
+        return buildEdgeInfoFromEdgeYaml(edgeYaml);
     }
 }

maven-projects/info/src/main/java/org/apache/graphar/info/loader/StringGraphInfoLoader.java

@@ -48,14 +48,14 @@ public VertexInfo loadVertexInfo(URI vertexYamlUri) throws IOException {
         String yaml = readYaml(vertexYamlUri);
         Yaml vertexYamlLoader = new Yaml(new Constructor(VertexYaml.class, new LoaderOptions()));
         VertexYaml vertexYaml = vertexYamlLoader.load(yaml);
-        return buildVertexInfoFromGraphYaml(vertexYaml);
+        return buildVertexInfoFromVertexYaml(vertexYaml);
     }
 
     @Override
     public EdgeInfo loadEdgeInfo(URI edgeYamlUri) throws IOException {
         String yaml = readYaml(edgeYamlUri);
         Yaml edgeYamlLoader = new Yaml(new Constructor(EdgeYaml.class, new LoaderOptions()));
         EdgeYaml edgeYaml = edgeYamlLoader.load(yaml);
-        return buildEdgeInfoFromGraphYaml(edgeYaml);
+        return buildEdgeInfoFromEdgeYaml(edgeYaml);
     }
 }

maven-projects/info/src/main/java/org/apache/graphar/info/saver/BaseGraphInfoSaver.java

@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ *
+ *   http://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.apache.graphar.info.saver;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.net.URI;
+import org.apache.graphar.info.EdgeInfo;
+import org.apache.graphar.info.GraphInfo;
+import org.apache.graphar.info.VertexInfo;
+
+public abstract class BaseGraphInfoSaver implements GraphInfoSaver {
+
+    public abstract Writer writeYaml(URI uri) throws IOException;
+
+    @Override
+    public void save(URI graphInfoUri, GraphInfo graphInfo) throws IOException {
+        Writer writer = writeYaml(graphInfoUri);
+        writer.write(graphInfo.dump(graphInfoUri));
+        writer.close();
+
+        for (VertexInfo vertexInfo : graphInfo.getVertexInfos()) {
+            URI saveUri = graphInfoUri.resolve(graphInfo.getStoreUri(vertexInfo));
+            save(saveUri, vertexInfo);
+        }
+        for (EdgeInfo edgeInfo : graphInfo.getEdgeInfos()) {
+            URI saveUri = graphInfoUri.resolve(graphInfo.getStoreUri(edgeInfo));
+            save(saveUri, edgeInfo);
+        }
+    }
+
+    @Override
+    public void save(URI vertexInfoUri, VertexInfo vertexInfo) throws IOException {
+        Writer vertexWriter = writeYaml(vertexInfoUri);
+        vertexWriter.write(vertexInfo.dump());
+        vertexWriter.close();
+    }
+
+    @Override
+    public void save(URI edgeInfoUri, EdgeInfo edgeInfo) throws IOException {
+        Writer edgeWriter = writeYaml(edgeInfoUri);
+        edgeWriter.write(edgeInfo.dump());
+        edgeWriter.close();
+    }
+}

maven-projects/info/src/main/java/org/apache/graphar/info/saver/GraphSaver.java → maven-projects/info/src/main/java/org/apache/graphar/info/saver/GraphInfoSaver.java

@@ -20,9 +20,15 @@
 package org.apache.graphar.info.saver;
 
 import java.io.IOException;
+import java.net.URI;
+import org.apache.graphar.info.EdgeInfo;
 import org.apache.graphar.info.GraphInfo;
+import org.apache.graphar.info.VertexInfo;
 
-@FunctionalInterface
-public interface GraphSaver {
-    void save(String path, GraphInfo graphInfo) throws IOException;
+public interface GraphInfoSaver {
+    void save(URI graphInfoUri, GraphInfo graphInfo) throws IOException;
+
+    void save(URI vertexInfoUri, VertexInfo vertexInfo) throws IOException;
+
+    void save(URI edgeInfoUri, EdgeInfo edgeInfo) throws IOException;
 }