Faster XML Jackson usage in Portal Code and replacing it with Gson

Areas where Jackson is Used:

Direct usage of Jackson by Portal code
Indirect dependency through other packages
Frameworks configured with Jackson like Spring Boot

Modules with direct dependency on Jackson package:

Portal-SDK:

epsdk-fw
epsdk-analytics
epsdk-app-common
epsdk-app-os
epsdk-core
epsdk-domain
epsdk-music
epsdk-workflow
epsdk-aaf

Portal:

Portal-BE-Common:
Portal-BE-OS:
Portal-widget-ms:

Packages used that have dependency on Jackson:

Portal-SDK:

org.elasticsearch:elasticsearch:jar – Not using this package anywhere in the code and can be removed, as confirmed by Sunder.
org.onap.portal.sdk:epsdk-music:jar

Portal:

com.orbitz.consul:consul-client:jar - Excluded the jacskon dependency for this package and ran the build. The build is successful, however this needs to tested with real time scenarios.
org.elasticsearch:elasticsearch:jar - Not using this package anywhere in the code and can be removed, as confirmed by Sunder
Spring Boot

Code Analysis:

Portal-SDK: Approximately 60+ files that inculde fatserxml jackson excluding test files.
Portal: Approximately 60+ files that inculde fatserxml jackson excluding test files

Using Gson In our Code:

Gson Maven Dependency:

<groupId>com.google.code.gson</groupId>

<version>${gson.version}</version>

</dependency>

POC- Replacing Jackson with Gson in our code:

Gson FromJson method as replacement for Jackson readValue method-Replaced Jackson methods with Gson methods in saveRoleFunction() method of RoleFunctionListController class as below,

Replaced this,

public void saveRoleFunction() {

String data = roleFunc;

RoleFunction availableRoleFunction = mapper.readValue(data, RoleFunction.class);

System.out.println("mapper.readVlaue:"+availableRoleFunction);

}

With this,

public void saveRoleFunction() {

String data = roleFunc;

RoleFunction roleFunctonAvailable = gson.fromJson(data, RoleFunction.class);

System.out.println("gson:fromJson:"+roleFunctonAvailable);

}

Output for both methods, gson.fromJson() and mapper.readValue, is same.

Gson toJson method as replacement for Jackson writeValueAsString method-Replaced Jackson methods with Gson methods in buildJsonResponse() method of JsonMessage class as below,

Replaced this,

public static String buildJsonResponse(boolean success, String msg) {

String json = null;

json = new ObjectMapper().writeValueAsString(response);

System.out.println("mapper.WriteValueAsString:"+json);

return json;

}

With this,

public static String buildJsonResponse(boolean success, String msg) {

String jsonFromGson = null;

jsonFromGson = new Gson().toJson(response);

System.out.println("Gson().toJson:"+jsonFromGson);

return jsonFromGson;

}

Output for both methods, gson.fromJson() and mapper.readValue, is same

Replacing spring Boot Jackson dependencies with Gson:

https://www.callicoder.com/configuring-spring-boot-to-use-gson-instead-of-jackson/

Jackson Methods used in our code and their equivalents in Gson:

Below are few of the methods and their usages in Gson that can be used as replacements for Jackson,

Jackson Method	Jackson Class	Usage	GSON Equivalent Method	GSON Equivalent Class	Usage

Jackson Method	Jackson Class	Usage	GSON Equivalent Method	GSON Equivalent Class	Usage
readValue	jackson.databind.ObjectMapper	<ObjectType> obj = mapper.readValue(JsonString, ClassType);	fromJson	com.google.gson.Gson;	<ObjectType> obj = gson.fromJson(data, RoleFunction.class);
writeValueAsString	jackson.databind.ObjectMapper	String json = new ObjectMapper().writeValueAsString(Object);	toJson	com.google.gson.Gson;	String resultJson = new Gson().toJson(Object);
configure	jackson.databind.ObjectMapper	objectMapper.configure(com.fasterxml.jackson.databind.SerializationFeature.WRITE_DATES_AS_TIMESTAMPS) objectMapper.disable(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES)	Use GsonBuilder to construct a Gson instance when you need to set configuration options other than the default	com.google.gson.GsonBuilder	Gson gson = new GsonBuilder() .serializeNulls() .setDateFormat(DateFormat.LONG) .create();
readTree	jackson.databind.ObjectMapper	JsonNode root = mapper.readTree(request.getReader());	parse	com.google.gson.JsonParser	JsonElement rootNode = parser.parse(jsonString);
NA	jackson.databind.JsonNode;	Base class for all JSON nodes, which form the basis of JSON	NA	import com.google.gson.JsonElement;	class representing an element of Json. It could either be a JsonObject, a JsonArray, a JsonPrimitive or a JsonNull
NA	jackson.core.type.TypeReference	TypeReference<List<Type>> typeRef = new TypeReference<List<Type>>() {}; List<Type> listObj = mapper.readValue(requestBody, typeRef);	NA	import com.google.gson.reflect.TypeToken;	listObj = gson.fromJson(jsonString, new TypeToken<Hashtable<String, Type>>() {}.getType());
NA	import com.fasterxml.jackson.databind.type.TypeFactory;		NA
NA	jackson.annotation.JsonIgnoreProperties;	JsonIgnoreProperties(ignoreUnknown = true)	NA	com.google.gson.annotations.Expose	GSON @Expose annotation using GsonBuilder.excludeFieldsWithoutExposeAnnotation().
NA	jackson.annotation.JsonRootName;	JsonRootName(value="abc") public class ClassName {}	NA	javax.xml.bind.annotation.XmlElement	XmlRootElement public class ClassName {}

References:
https://www.baeldung.com/jackson-vs-gson
http://websystique.com/java/json/gson-json-annotations-example/
https://www.tutorialspoint.com/gson/gson_tree_model.htm
https://google.github.io/gson/apidocs/index.html?com/google/gson/class-use/JsonElement.html
https://www.baeldung.com/gson-deserialization-guide
http://websystique.com/java/json/gson-tree-model-example/