From 6ed36b2b1ab8a3442b82abc2eb2feba26b8c4cc7 Mon Sep 17 00:00:00 2001
From: Michael Haney <haneym@google.com>
Date: Fri, 14 Dec 2018 22:53:11 -0800
Subject: [PATCH 1/3] Implement NSSecureCodingProtocol for GDLLogEvent

---
 .../GoogleDataLogger/Classes/GDLLogEvent.h    |  4 +--
 .../GoogleDataLogger/Classes/GDLLogEvent.m    | 30 +++++++++++++++++++
 GoogleDataLogger/Tests/GDLLogEventTest.m      | 23 ++++++++++++++
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h
index 8f5d0e81e2d..90f3cb27426 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h
@@ -39,7 +39,7 @@ typedef NS_ENUM(NSInteger, GDLLogQoS) {
   GDLLogQoSFast = 4
 };
 
-@interface GDLLogEvent : NSObject
+@interface GDLLogEvent : NSObject <NSSecureCoding>
 
 /** The log map identifier, to allow backends to map the extension property to a proto. */
 @property(readonly, nonatomic) NSString *logMapID;
@@ -49,7 +49,7 @@ typedef NS_ENUM(NSInteger, GDLLogQoS) {
 
 /** The log object itself, encapsulated in the transport of your choice, as long as it implements
  * the GDLLogProto protocol. */
-@property(nonatomic) id<GDLLogProto> extension;
+@property(nonatomic) NSData *extensionData;
 
 /** The quality of service tier this log belongs to. */
 @property(nonatomic) GDLLogQoS qosTier;
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
index ae7ca6eb586..da639d655a1 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
@@ -29,4 +29,34 @@ - (instancetype)initWithLogMapID:(NSString *)logMapID logTarget:(NSInteger)logTa
   return self;
 }
 
+#pragma mark - NSSecureCoding and NSCoding Protocols
+
++ (BOOL)supportsSecureCoding {
+  return YES;
+}
+
+- (id)initWithCoder:(NSCoder *)aDecoder {
+  NSString *logMapID = [aDecoder decodeObjectOfClass:[NSObject class] forKey:@"_logMapID"];
+  NSInteger logTarget = [aDecoder decodeIntegerForKey:@"_logTarget"];
+  self = [self initWithLogMapID:logMapID logTarget:logTarget];
+  if (self) {
+    _extensionData = [aDecoder decodeObjectOfClass:[NSData class] forKey:@"_extensionData"];
+    _qosTier = [aDecoder decodeIntegerForKey:@"_qosTier"];
+    _clockSnapshot.timeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotTimeMillis"];
+    _clockSnapshot.uptimeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotUpTimeMillis"];
+    _clockSnapshot.timezoneOffsetMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotTimezoneOffsetMillis"];
+  }
+  return self;
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder {
+  [aCoder encodeObject:_logMapID forKey:@"_logMapID"];
+  [aCoder encodeInteger:_logTarget forKey:@"_logTarget"];
+  [aCoder encodeObject:_extensionData forKey:@"_extensionData"];
+  [aCoder encodeInteger:_qosTier forKey:@"_qosTier"];
+  [aCoder encodeInt64:_clockSnapshot.timeMillis forKey:@"clockSnapshotTimeMillis"];
+  [aCoder encodeInt64:_clockSnapshot.uptimeMillis forKey:@"clockSnapshotUpTimeMillis"];
+  [aCoder encodeInt64:_clockSnapshot.timezoneOffsetMillis forKey:@"clockSnapshotTimezoneOffsetMillis"];
+}
+
 @end
diff --git a/GoogleDataLogger/Tests/GDLLogEventTest.m b/GoogleDataLogger/Tests/GDLLogEventTest.m
index c96c00907ee..081266edf9e 100644
--- a/GoogleDataLogger/Tests/GDLLogEventTest.m
+++ b/GoogleDataLogger/Tests/GDLLogEventTest.m
@@ -24,9 +24,32 @@ @interface GDLLogEventTest : XCTestCase
 
 @implementation GDLLogEventTest
 
+/** Tests the designated initializer. */
 - (void)testInit {
   XCTAssertNotNil([[GDLLogEvent alloc] initWithLogMapID:@"1" logTarget:1]);
   XCTAssertThrows([[GDLLogEvent alloc] initWithLogMapID:@"" logTarget:1]);
 }
 
+/** Tests NSKeyedArchiver encoding and decoding. */
+- (void)testArchiving {
+  XCTAssertTrue([GDLLogEvent supportsSecureCoding]);
+  GDLLogClockSnapshot clockSnapshot = {10, 100, 1000};
+  GDLLogEvent *logEvent = [[GDLLogEvent alloc] initWithLogMapID:@"testID" logTarget:42];
+  logEvent.extensionData = [@"someData" dataUsingEncoding:NSUTF8StringEncoding];
+  logEvent.qosTier = GDLLogQoSTelemetry;
+  logEvent.clockSnapshot = clockSnapshot;
+
+  NSData *archiveData = [NSKeyedArchiver archivedDataWithRootObject:logEvent];
+  logEvent = nil;
+
+  logEvent = [NSKeyedUnarchiver unarchiveObjectWithData:archiveData];
+  XCTAssertEqualObjects(logEvent.logMapID, @"testID");
+  XCTAssertEqual(logEvent.logTarget, 42);
+  XCTAssertEqualObjects(logEvent.extensionData, [@"someData" dataUsingEncoding:NSUTF8StringEncoding]);
+  XCTAssertEqual(logEvent.qosTier, GDLLogQoSTelemetry);
+  XCTAssertEqual(logEvent.clockSnapshot.timeMillis, 10);
+  XCTAssertEqual(logEvent.clockSnapshot.uptimeMillis, 100);
+  XCTAssertEqual(logEvent.clockSnapshot.timezoneOffsetMillis, 1000);
+}
+
 @end

From 8c848141c466b9aa55c85ec3d8fd05c9aa8fb3c2 Mon Sep 17 00:00:00 2001
From: Michael Haney <haneym@google.com>
Date: Fri, 14 Dec 2018 23:07:34 -0800
Subject: [PATCH 2/3] Style changes.

---
 GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m | 6 ++++--
 GoogleDataLogger/Tests/GDLLogEventTest.m                | 3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
index da639d655a1..2b4f42fe8bb 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
@@ -44,7 +44,8 @@ - (id)initWithCoder:(NSCoder *)aDecoder {
     _qosTier = [aDecoder decodeIntegerForKey:@"_qosTier"];
     _clockSnapshot.timeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotTimeMillis"];
     _clockSnapshot.uptimeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotUpTimeMillis"];
-    _clockSnapshot.timezoneOffsetMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotTimezoneOffsetMillis"];
+    _clockSnapshot.timezoneOffsetMillis =
+        [aDecoder decodeInt64ForKey:@"clockSnapshotTimezoneOffsetMillis"];
   }
   return self;
 }
@@ -56,7 +57,8 @@ - (void)encodeWithCoder:(NSCoder *)aCoder {
   [aCoder encodeInteger:_qosTier forKey:@"_qosTier"];
   [aCoder encodeInt64:_clockSnapshot.timeMillis forKey:@"clockSnapshotTimeMillis"];
   [aCoder encodeInt64:_clockSnapshot.uptimeMillis forKey:@"clockSnapshotUpTimeMillis"];
-  [aCoder encodeInt64:_clockSnapshot.timezoneOffsetMillis forKey:@"clockSnapshotTimezoneOffsetMillis"];
+  [aCoder encodeInt64:_clockSnapshot.timezoneOffsetMillis
+               forKey:@"clockSnapshotTimezoneOffsetMillis"];
 }
 
 @end
diff --git a/GoogleDataLogger/Tests/GDLLogEventTest.m b/GoogleDataLogger/Tests/GDLLogEventTest.m
index 081266edf9e..00abf39e739 100644
--- a/GoogleDataLogger/Tests/GDLLogEventTest.m
+++ b/GoogleDataLogger/Tests/GDLLogEventTest.m
@@ -45,7 +45,8 @@ - (void)testArchiving {
   logEvent = [NSKeyedUnarchiver unarchiveObjectWithData:archiveData];
   XCTAssertEqualObjects(logEvent.logMapID, @"testID");
   XCTAssertEqual(logEvent.logTarget, 42);
-  XCTAssertEqualObjects(logEvent.extensionData, [@"someData" dataUsingEncoding:NSUTF8StringEncoding]);
+  XCTAssertEqualObjects(logEvent.extensionData,
+                        [@"someData" dataUsingEncoding:NSUTF8StringEncoding]);
   XCTAssertEqual(logEvent.qosTier, GDLLogQoSTelemetry);
   XCTAssertEqual(logEvent.clockSnapshot.timeMillis, 10);
   XCTAssertEqual(logEvent.clockSnapshot.uptimeMillis, 100);

From 01e183edfdc7ce920918779d3a0b150d077b2388 Mon Sep 17 00:00:00 2001
From: Michael Haney <haneym@google.com>
Date: Mon, 17 Dec 2018 15:30:22 -0800
Subject: [PATCH 3/3] Refactor to address some comments and structure

GDLLogEvent and GDLLogProto are moved to the public folder.

GDLLogEvent has had some public API moved to a private header.

GDLLogWriter now writes the extension object to data after transforming, for serialization purposes.

Various headers updated to conform to module header rules.
---
 .../GoogleDataLogger/Classes/GDLLogEvent.m    | 54 +++++++++++++------
 .../GoogleDataLogger/Classes/GDLLogWriter.m   | 12 +++++
 .../Classes/Private/GDLLogEvent_Private.h     | 36 +++++++++++++
 .../Classes/{ => Public}/GDLLogEvent.h        |  9 +---
 .../Classes/{ => Public}/GDLLogProto.h        |  0
 .../Classes/Public/GDLLogger.h                | 12 +++--
 .../Classes/Public/GoogleDataLogger.h         |  2 +
 .../DependencyWrappers/GDLConsoleLogger.h     |  5 +-
 GoogleDataLogger/Tests/GDLLogEventTest.m      | 24 +++++----
 GoogleDataLogger/Tests/GDLLogWriterTest.m     |  5 ++
 GoogleDataLogger/Tests/GDLLoggerTest.m        |  5 ++
 .../Helpers/GDLLogExtensionTesterClasses.h    | 31 +++++++++++
 .../Helpers/GDLLogExtensionTesterClasses.m    | 33 ++++++++++++
 13 files changed, 189 insertions(+), 39 deletions(-)
 create mode 100644 GoogleDataLogger/GoogleDataLogger/Classes/Private/GDLLogEvent_Private.h
 rename GoogleDataLogger/GoogleDataLogger/Classes/{ => Public}/GDLLogEvent.h (89%)
 rename GoogleDataLogger/GoogleDataLogger/Classes/{ => Public}/GDLLogProto.h (100%)
 create mode 100644 GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.h
 create mode 100644 GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.m

diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
index 2b4f42fe8bb..36c3cc78497 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.m
@@ -14,7 +14,9 @@
  * limitations under the License.
  */
 
-#import "GDLLogEvent.h"
+#import <GoogleDataLogger/GDLLogEvent.h>
+
+#import "GDLLogEvent_Private.h"
 
 @implementation GDLLogEvent
 
@@ -31,34 +33,54 @@ - (instancetype)initWithLogMapID:(NSString *)logMapID logTarget:(NSInteger)logTa
 
 #pragma mark - NSSecureCoding and NSCoding Protocols
 
+/** NSCoding key for logMapID property. */
+static NSString *logMapIDKey = @"_logMapID";
+
+/** NSCoding key for logTarget property. */
+static NSString *logTargetKey = @"_logTarget";
+
+/** NSCoding key for extensionBytes property. */
+static NSString *extensionBytesKey = @"_extensionBytes";
+
+/** NSCoding key for qosTier property. */
+static NSString *qosTierKey = @"_qosTier";
+
+/** NSCoding key for clockSnapshot.timeMillis property. */
+static NSString *clockSnapshotTimeMillisKey = @"_clockSnapshotTimeMillis";
+
+/** NSCoding key for clockSnapshot.uptimeMillis property. */
+static NSString *clockSnapshotUpTimeMillis = @"_clockSnapshotUpTimeMillis";
+
+/** NSCoding key for clockSnapshot.timezoneOffsetMillis property. */
+static NSString *clockSnapshotTimezoneOffsetMillis = @"_clockSnapshotTimezoneOffsetMillis";
+
 + (BOOL)supportsSecureCoding {
   return YES;
 }
 
 - (id)initWithCoder:(NSCoder *)aDecoder {
-  NSString *logMapID = [aDecoder decodeObjectOfClass:[NSObject class] forKey:@"_logMapID"];
-  NSInteger logTarget = [aDecoder decodeIntegerForKey:@"_logTarget"];
+  NSString *logMapID = [aDecoder decodeObjectOfClass:[NSObject class] forKey:logMapIDKey];
+  NSInteger logTarget = [aDecoder decodeIntegerForKey:logTargetKey];
   self = [self initWithLogMapID:logMapID logTarget:logTarget];
   if (self) {
-    _extensionData = [aDecoder decodeObjectOfClass:[NSData class] forKey:@"_extensionData"];
-    _qosTier = [aDecoder decodeIntegerForKey:@"_qosTier"];
-    _clockSnapshot.timeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotTimeMillis"];
-    _clockSnapshot.uptimeMillis = [aDecoder decodeInt64ForKey:@"clockSnapshotUpTimeMillis"];
+    _extensionBytes = [aDecoder decodeObjectOfClass:[NSData class] forKey:extensionBytesKey];
+    _qosTier = [aDecoder decodeIntegerForKey:qosTierKey];
+    _clockSnapshot.timeMillis = [aDecoder decodeInt64ForKey:clockSnapshotTimeMillisKey];
+    _clockSnapshot.uptimeMillis = [aDecoder decodeInt64ForKey:clockSnapshotUpTimeMillis];
     _clockSnapshot.timezoneOffsetMillis =
-        [aDecoder decodeInt64ForKey:@"clockSnapshotTimezoneOffsetMillis"];
+        [aDecoder decodeInt64ForKey:clockSnapshotTimezoneOffsetMillis];
   }
   return self;
 }
 
 - (void)encodeWithCoder:(NSCoder *)aCoder {
-  [aCoder encodeObject:_logMapID forKey:@"_logMapID"];
-  [aCoder encodeInteger:_logTarget forKey:@"_logTarget"];
-  [aCoder encodeObject:_extensionData forKey:@"_extensionData"];
-  [aCoder encodeInteger:_qosTier forKey:@"_qosTier"];
-  [aCoder encodeInt64:_clockSnapshot.timeMillis forKey:@"clockSnapshotTimeMillis"];
-  [aCoder encodeInt64:_clockSnapshot.uptimeMillis forKey:@"clockSnapshotUpTimeMillis"];
-  [aCoder encodeInt64:_clockSnapshot.timezoneOffsetMillis
-               forKey:@"clockSnapshotTimezoneOffsetMillis"];
+  [aCoder encodeObject:_logMapID forKey:logMapIDKey];
+  [aCoder encodeInteger:_logTarget forKey:logTargetKey];
+  [aCoder encodeObject:_extensionBytes forKey:extensionBytesKey];
+  [aCoder encodeInteger:_qosTier forKey:qosTierKey];
+  [aCoder encodeInt64:_clockSnapshot.timeMillis forKey:clockSnapshotTimeMillisKey];
+  [aCoder encodeInt64:_clockSnapshot.uptimeMillis forKey:clockSnapshotUpTimeMillis];
+  [aCoder encodeInt64:_clockSnapshot.timezoneOffsetMillis forKey:clockSnapshotTimezoneOffsetMillis];
 }
 
 @end
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogWriter.m b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogWriter.m
index 71590b480e9..7a9d2cb2fcb 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogWriter.m
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogWriter.m
@@ -20,6 +20,7 @@
 #import <GoogleDataLogger/GDLLogTransformer.h>
 
 #import "GDLConsoleLogger.h"
+#import "GDLLogEvent_Private.h"
 #import "GDLLogStorage.h"
 
 @implementation GDLLogWriter
@@ -60,6 +61,17 @@ - (void)writeLog:(GDLLogEvent *)log
         return;
       }
     }
+
+    // Convert the extension to bytes after transforming.
+    NSAssert([log.extension respondsToSelector:@selector(protoBytes)],
+             @"The log event's extension must respond to -protoBytes.");
+    if ([log.extension respondsToSelector:@selector(protoBytes)]) {
+      log.extensionBytes = [log.extension protoBytes];
+      log.extension = nil;
+    } else {
+      GDLLogWarning(GDLMCWExtensionMissingBytesImpl, @"%@",
+                    @"The log event's extension must respond to -protoBytes.");
+    }
     // TODO(mikehaney24): [[GDLLogStorage sharedInstance] storeLog:transformedLog];
   });
 }
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/Private/GDLLogEvent_Private.h b/GoogleDataLogger/GoogleDataLogger/Classes/Private/GDLLogEvent_Private.h
new file mode 100644
index 00000000000..1df364bcb58
--- /dev/null
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/Private/GDLLogEvent_Private.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed 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.
+ */
+
+#import "GDLLogEvent.h"
+
+#import "GDLLogClock.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface GDLLogEvent ()
+
+/** The serialized bytes of the log object. */
+@property(nonatomic) NSData *extensionBytes;
+
+/** The quality of service tier this log belongs to. */
+@property(nonatomic) GDLLogQoS qosTier;
+
+/** The clock snapshot at the time of logging. */
+@property(nonatomic) GDLLogClockSnapshot clockSnapshot;
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogEvent.h
similarity index 89%
rename from GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h
rename to GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogEvent.h
index 90f3cb27426..f3931b2e076 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogEvent.h
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogEvent.h
@@ -16,7 +16,6 @@
 
 #import <Foundation/Foundation.h>
 
-#import "GDLLogClock.h"
 #import "GDLLogProto.h"
 
 NS_ASSUME_NONNULL_BEGIN
@@ -49,13 +48,7 @@ typedef NS_ENUM(NSInteger, GDLLogQoS) {
 
 /** The log object itself, encapsulated in the transport of your choice, as long as it implements
  * the GDLLogProto protocol. */
-@property(nonatomic) NSData *extensionData;
-
-/** The quality of service tier this log belongs to. */
-@property(nonatomic) GDLLogQoS qosTier;
-
-/** The clock snapshot at the time of logging. */
-@property(nonatomic) GDLLogClockSnapshot clockSnapshot;
+@property(nullable, nonatomic) id<GDLLogProto> extension;
 
 // Please use the designated initializer.
 - (instancetype)init NS_UNAVAILABLE;
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/GDLLogProto.h b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogProto.h
similarity index 100%
rename from GoogleDataLogger/GoogleDataLogger/Classes/GDLLogProto.h
rename to GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogProto.h
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogger.h b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogger.h
index 1938c36f16d..ea52804dc38 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogger.h
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GDLLogger.h
@@ -38,15 +38,19 @@ NS_ASSUME_NONNULL_BEGIN
                  logTransformers:(nullable NSArray<id<GDLLogTransformer>> *)logTransformers
                        logTarget:(NSInteger)logTarget NS_DESIGNATED_INITIALIZER;
 
-/** Logs an internal telemetry event. Logs sent using this API are lower in priority, and sometimes
- *  won't be sent on their own.
+/** Copies and logs an internal telemetry event. Logs sent using this API are lower in priority, and
+ * sometimes won't be sent on their own.
+ *
+ * @note This will convert the log event's extension proto to data and release the original log.
  *
  * @param logEvent The log event to log.
  */
 - (void)logTelemetryEvent:(GDLLogEvent *)logEvent;
 
-/** Logs an SDK service data event. Logs send using this API are higher in priority, and will cause
- *  a network request at some point in the relative near future.
+/** Copies and logs an SDK service data event. Logs send using this API are higher in priority, and
+ * will cause a network request at some point in the relative near future.
+ *
+ * @note This will convert the log event's extension proto to data and release the original log.
  *
  * @param logEvent The log event to log.
  */
diff --git a/GoogleDataLogger/GoogleDataLogger/Classes/Public/GoogleDataLogger.h b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GoogleDataLogger.h
index 6ba563c5ea5..091625895eb 100644
--- a/GoogleDataLogger/GoogleDataLogger/Classes/Public/GoogleDataLogger.h
+++ b/GoogleDataLogger/GoogleDataLogger/Classes/Public/GoogleDataLogger.h
@@ -14,4 +14,6 @@
  * limitations under the License.
  */
 
+#import "GDLLogEvent.h"
+#import "GDLLogTransformer.h"
 #import "GDLLogger.h"
diff --git a/GoogleDataLogger/GoogleDataLogger/DependencyWrappers/GDLConsoleLogger.h b/GoogleDataLogger/GoogleDataLogger/DependencyWrappers/GDLConsoleLogger.h
index aaaa23c6edd..b1ce4fbe3a1 100644
--- a/GoogleDataLogger/GoogleDataLogger/DependencyWrappers/GDLConsoleLogger.h
+++ b/GoogleDataLogger/GoogleDataLogger/DependencyWrappers/GDLConsoleLogger.h
@@ -28,7 +28,10 @@ static GULLoggerService kGDLConsoleLogger = @"[GoogleDataLogger]";
 typedef NS_ENUM(NSInteger, GDLMessageCode) {
 
   /** For warning messages concerning transform: not being implemented by a log transformer. */
-  GDLMCWTransformerDoesntImplementTransform = 1
+  GDLMCWTransformerDoesntImplementTransform = 1,
+
+  /** For warning messages concerning protoBytes: not being implemented by a log extension. */
+  GDLMCWExtensionMissingBytesImpl = 2
 };
 
 /** */
diff --git a/GoogleDataLogger/Tests/GDLLogEventTest.m b/GoogleDataLogger/Tests/GDLLogEventTest.m
index 00abf39e739..d12468cc593 100644
--- a/GoogleDataLogger/Tests/GDLLogEventTest.m
+++ b/GoogleDataLogger/Tests/GDLLogEventTest.m
@@ -16,7 +16,9 @@
 
 #import <XCTest/XCTest.h>
 
-#import "GDLLogEvent.h"
+#import <GoogleDataLogger/GDLLogEvent.h>
+
+#import "GDLLogEvent_Private.h"
 
 @interface GDLLogEventTest : XCTestCase
 
@@ -35,22 +37,24 @@ - (void)testArchiving {
   XCTAssertTrue([GDLLogEvent supportsSecureCoding]);
   GDLLogClockSnapshot clockSnapshot = {10, 100, 1000};
   GDLLogEvent *logEvent = [[GDLLogEvent alloc] initWithLogMapID:@"testID" logTarget:42];
-  logEvent.extensionData = [@"someData" dataUsingEncoding:NSUTF8StringEncoding];
+  logEvent.extensionBytes = [@"someData" dataUsingEncoding:NSUTF8StringEncoding];
   logEvent.qosTier = GDLLogQoSTelemetry;
   logEvent.clockSnapshot = clockSnapshot;
 
   NSData *archiveData = [NSKeyedArchiver archivedDataWithRootObject:logEvent];
+
+  // To ensure that all the objects being retained by the original logEvent are dealloc'd.
   logEvent = nil;
 
-  logEvent = [NSKeyedUnarchiver unarchiveObjectWithData:archiveData];
-  XCTAssertEqualObjects(logEvent.logMapID, @"testID");
-  XCTAssertEqual(logEvent.logTarget, 42);
-  XCTAssertEqualObjects(logEvent.extensionData,
+  GDLLogEvent *decodedLogEvent = [NSKeyedUnarchiver unarchiveObjectWithData:archiveData];
+  XCTAssertEqualObjects(decodedLogEvent.logMapID, @"testID");
+  XCTAssertEqual(decodedLogEvent.logTarget, 42);
+  XCTAssertEqualObjects(decodedLogEvent.extensionBytes,
                         [@"someData" dataUsingEncoding:NSUTF8StringEncoding]);
-  XCTAssertEqual(logEvent.qosTier, GDLLogQoSTelemetry);
-  XCTAssertEqual(logEvent.clockSnapshot.timeMillis, 10);
-  XCTAssertEqual(logEvent.clockSnapshot.uptimeMillis, 100);
-  XCTAssertEqual(logEvent.clockSnapshot.timezoneOffsetMillis, 1000);
+  XCTAssertEqual(decodedLogEvent.qosTier, GDLLogQoSTelemetry);
+  XCTAssertEqual(decodedLogEvent.clockSnapshot.timeMillis, 10);
+  XCTAssertEqual(decodedLogEvent.clockSnapshot.uptimeMillis, 100);
+  XCTAssertEqual(decodedLogEvent.clockSnapshot.timezoneOffsetMillis, 1000);
 }
 
 @end
diff --git a/GoogleDataLogger/Tests/GDLLogWriterTest.m b/GoogleDataLogger/Tests/GDLLogWriterTest.m
index d7e88416915..5a9f80e9302 100644
--- a/GoogleDataLogger/Tests/GDLLogWriterTest.m
+++ b/GoogleDataLogger/Tests/GDLLogWriterTest.m
@@ -19,6 +19,7 @@
 #import <GoogleDataLogger/GDLLogTransformer.h>
 
 #import "GDLLogEvent.h"
+#import "GDLLogExtensionTesterClasses.h"
 #import "GDLLogWriter.h"
 #import "GDLLogWriter_Private.h"
 
@@ -66,6 +67,7 @@ - (void)testSharedInstance {
 - (void)testWriteLogWithoutTransformers {
   GDLLogWriter *writer = [GDLLogWriter sharedInstance];
   GDLLogEvent *log = [[GDLLogEvent alloc] initWithLogMapID:@"1" logTarget:1];
+  log.extension = [[GDLLogExtensionTesterSimple alloc] init];
   XCTAssertNoThrow([writer writeLog:log afterApplyingTransformers:nil]);
   dispatch_sync(writer.logWritingQueue, ^{
                     // TODO(mikehaney24): Assert that storage contains the log.
@@ -76,6 +78,7 @@ - (void)testWriteLogWithoutTransformers {
 - (void)testWriteLogWithTransformersThatNilTheLog {
   GDLLogWriter *writer = [GDLLogWriter sharedInstance];
   GDLLogEvent *log = [[GDLLogEvent alloc] initWithLogMapID:@"2" logTarget:1];
+  log.extension = [[GDLLogExtensionTesterSimple alloc] init];
   NSArray<id<GDLLogTransformer>> *transformers =
       @[ [[GDLLogWriterTestNilingTransformer alloc] init] ];
   XCTAssertNoThrow([writer writeLog:log afterApplyingTransformers:transformers]);
@@ -88,6 +91,7 @@ - (void)testWriteLogWithTransformersThatNilTheLog {
 - (void)testWriteLogWithTransformersThatCreateANewLog {
   GDLLogWriter *writer = [GDLLogWriter sharedInstance];
   GDLLogEvent *log = [[GDLLogEvent alloc] initWithLogMapID:@"2" logTarget:1];
+  log.extension = [[GDLLogExtensionTesterSimple alloc] init];
   NSArray<id<GDLLogTransformer>> *transformers =
       @[ [[GDLLogWriterTestNewLogTransformer alloc] init] ];
   XCTAssertNoThrow([writer writeLog:log afterApplyingTransformers:transformers]);
@@ -100,6 +104,7 @@ - (void)testWriteLogWithTransformersThatCreateANewLog {
 - (void)testWriteLogWithBadTransformer {
   GDLLogWriter *writer = [GDLLogWriter sharedInstance];
   GDLLogEvent *log = [[GDLLogEvent alloc] initWithLogMapID:@"2" logTarget:1];
+  log.extension = [[GDLLogExtensionTesterSimple alloc] init];
   NSArray *transformers = @[ [[NSObject alloc] init] ];
   @try {
     dispatch_sync(writer.logWritingQueue, ^{
diff --git a/GoogleDataLogger/Tests/GDLLoggerTest.m b/GoogleDataLogger/Tests/GDLLoggerTest.m
index 2c7f5d4cebb..b205400e076 100644
--- a/GoogleDataLogger/Tests/GDLLoggerTest.m
+++ b/GoogleDataLogger/Tests/GDLLoggerTest.m
@@ -16,8 +16,11 @@
 
 #import <XCTest/XCTest.h>
 
+#import <GoogleDataLogger/GDLLogEvent.h>
 #import <GoogleDataLogger/GDLLogger.h>
 
+#import "GDLLogExtensionTesterClasses.h"
+
 @interface GDLLoggerTest : XCTestCase
 
 @end
@@ -34,6 +37,7 @@ - (void)testInit {
 - (void)testLogTelemetryEvent {
   GDLLogger *logger = [[GDLLogger alloc] initWithLogMapID:@"1" logTransformers:nil logTarget:1];
   GDLLogEvent *event = [logger newEvent];
+  event.extension = [[GDLLogExtensionTesterSimple alloc] init];
   XCTAssertNoThrow([logger logTelemetryEvent:event]);
 }
 
@@ -41,6 +45,7 @@ - (void)testLogTelemetryEvent {
 - (void)testLogDataEvent {
   GDLLogger *logger = [[GDLLogger alloc] initWithLogMapID:@"1" logTransformers:nil logTarget:1];
   GDLLogEvent *event = [logger newEvent];
+  event.extension = [[GDLLogExtensionTesterSimple alloc] init];
   XCTAssertNoThrow([logger logDataEvent:event]);
 }
 
diff --git a/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.h b/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.h
new file mode 100644
index 00000000000..9c476446107
--- /dev/null
+++ b/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed 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.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import <GoogleDataLogger/GDLLogProto.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** A class to represent a simple log proto. */
+@interface GDLLogExtensionTesterSimple : NSObject <GDLLogProto>
+
+/** A string that will be turned into bytes. */
+@property(nonatomic) NSString *aString;
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.m b/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.m
new file mode 100644
index 00000000000..e071e98658f
--- /dev/null
+++ b/GoogleDataLogger/Tests/Helpers/GDLLogExtensionTesterClasses.m
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed 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.
+ */
+
+#import "GDLLogExtensionTesterClasses.h"
+
+@implementation GDLLogExtensionTesterSimple
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    _aString = @"test";
+  }
+  return self;
+}
+
+- (NSData *)protoBytes {
+  return [_aString dataUsingEncoding:NSUTF8StringEncoding];
+}
+
+@end