Serving sdk changes for supporting snapshot plugins (#778)

* Changes for ddb

* Bumped up version to 0.4

Co-authored-by: dhanainme <[email protected]>

Author: dhaniram-kshirsagar

serving-sdk/pom.xml

@@ -4,7 +4,7 @@
   <groupId>org.pytorch</groupId>
   <artifactId>torchserve-plugins-sdk</artifactId>
   <packaging>jar</packaging>
-  <version>0.0.3</version>
+  <version>0.0.4</version>
   <name>torchserve-plugins-sdk</name>
   <description>
     SDK for PyTorch model server plugins

serving-sdk/src/main/java/org/pytorch/serve/servingsdk/snapshot/Snapshot.java

@@ -0,0 +1,54 @@
+package org.pytorch.serve.servingsdk.snapshot;
+
+import com.google.gson.JsonObject;
+import java.util.Map;
+
+public class Snapshot {
+    private String name;
+    private int modelCount;
+    private long created;
+    private Map<String, Map<String, JsonObject>> models;
+
+    public Snapshot(String snaspshotName, int modelCount) {
+        this.name = snaspshotName;
+        this.setModelCount(modelCount);
+        this.created = System.currentTimeMillis();
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Map<String, Map<String, JsonObject>> getModels() {
+        return models;
+    }
+
+    public void setModels(Map<String, Map<String, JsonObject>> models) {
+        this.models = models;
+    }
+
+    public long getCreated() {
+        return created;
+    }
+
+    public void setCreated(long created) {
+        this.created = created;
+    }
+
+    @Override
+    public String toString() {
+        return "Checkpoint [name=" + name + ", created=" + created + ", models=" + models + "]";
+    }
+
+    public int getModelCount() {
+        return modelCount;
+    }
+
+    public void setModelCount(int modelCount) {
+        this.modelCount = modelCount;
+    }
+}

serving-sdk/src/main/java/org/pytorch/serve/servingsdk/snapshot/SnapshotSerializer.java

@@ -0,0 +1,13 @@
+package org.pytorch.serve.servingsdk.snapshot;
+
+import java.io.IOException;
+import java.util.Properties;
+
+public interface SnapshotSerializer {
+
+    void saveSnapshot(Snapshot snapshot, final Properties prop) throws IOException;
+
+    Snapshot getSnapshot(String modelSnapshot) throws IOException;
+
+    Properties getLastSnapshot();
+}