From 1c7258aee00f0c3f9469c67f802a41ea2e12333b Mon Sep 17 00:00:00 2001
From: Joseph Zuniga-Daly <joseph.zunigadaly@r3.com>
Date: Thu, 25 Jun 2020 17:14:18 +0100
Subject: [PATCH] Add CheckpointCustomSerializer interface

---
 .../SerializationCustomSerializer.kt          | 25 +++++++++++++++++++
 ...ckNetworkCustomSerializerCheckpointTest.kt |  6 ++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/core/src/main/kotlin/net/corda/core/serialization/SerializationCustomSerializer.kt b/core/src/main/kotlin/net/corda/core/serialization/SerializationCustomSerializer.kt
index d0c910b638..5e7fac1bba 100644
--- a/core/src/main/kotlin/net/corda/core/serialization/SerializationCustomSerializer.kt
+++ b/core/src/main/kotlin/net/corda/core/serialization/SerializationCustomSerializer.kt
@@ -25,3 +25,28 @@ interface SerializationCustomSerializer<OBJ, PROXY> {
      */
     fun fromProxy(proxy: PROXY): OBJ
 }
+
+/**
+ * Allows CorDapps to provide custom serializers for third party libraries where those libraries cannot
+ * be recompiled with the -parameters flag rendering their classes natively serializable by Corda. In this case
+ * a proxy serializer can be written that extends this type whose purpose is to move between those an
+ * unserializable types and an intermediate representation.
+ *
+ * NOTE: The proxy object should be specified as a separate class. However, this can be defined within the
+ * scope of the custom serializer.
+ */
+@KeepForDJVM
+interface CheckpointCustomSerializer<OBJ, PROXY> {
+    /**
+     * Should facilitate the conversion of the third party object into the serializable
+     * local class specified by [PROXY]
+     */
+    fun toProxy(obj: OBJ): PROXY
+
+    /**
+     * Should facilitate the conversion of the proxy object into a new instance of the
+     * unserializable type
+     */
+    fun fromProxy(proxy: PROXY): OBJ
+
+}
diff --git a/node/src/integration-test/kotlin/net/corda/node/MockNetworkCustomSerializerCheckpointTest.kt b/node/src/integration-test/kotlin/net/corda/node/MockNetworkCustomSerializerCheckpointTest.kt
index 6ce4018c8b..a641835b36 100644
--- a/node/src/integration-test/kotlin/net/corda/node/MockNetworkCustomSerializerCheckpointTest.kt
+++ b/node/src/integration-test/kotlin/net/corda/node/MockNetworkCustomSerializerCheckpointTest.kt
@@ -6,6 +6,7 @@ import com.github.andrewoma.dexx.kollection.immutableMapOf
 import com.github.andrewoma.dexx.kollection.toImmutableMap
 import net.corda.core.flows.FlowLogic
 import net.corda.core.flows.StartableByRPC
+import net.corda.core.serialization.CheckpointCustomSerializer
 import net.corda.core.serialization.SerializationCustomSerializer
 import net.corda.testing.node.MockNetwork
 import net.corda.testing.node.MockNetworkParameters
@@ -92,7 +93,10 @@ class MockNetworkCustomSerializerCheckpointTest{
     // Custom serializers
 
     @Suppress("unused")
-    class TestSerializer : SerializationCustomSerializer<ImmutableMap<Any, Any>, HashMap<Any, Any>> {
+    class TestSerializer :
+            SerializationCustomSerializer<ImmutableMap<Any, Any>, HashMap<Any, Any>>,
+            CheckpointCustomSerializer<ImmutableMap<Any, Any>, HashMap<Any, Any>> {
+
         override fun toProxy(obj: ImmutableMap<Any, Any>): HashMap<Any, Any> {
             val proxy = HashMap<Any, Any>()
             return obj.toMap(proxy)