# Is there a porting guide from older version (202002 and 201906) to the last one 202012? **URL:** \ **Category:** AWS\ **Created:** [December 18, 2020, 3:29pm UTC](https://forums.freertos.org/t/is-there-a-porting-guide-from-older-version-202002-and-201906-to-the-last-one-202012/11383 "2020-12-18T15:29:50Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![MuneebAWS](https://avatars.discourse-cdn.com/v4/letter/m/f07891/32.png) [@MuneebAWS](https://forums.freertos.org/u/MuneebAWS)\ **Post date:** [December 18, 2020, 7:32pm UTC](https://forums.freertos.org/t/is-there-a-porting-guide-from-older-version-202002-and-201906-to-the-last-one-202012/11383/2 "2020-12-18T19:32:05Z")
Hi @EyalG, We do not have a porting guide for the move to the current APIs, although we have included a [compatibility layer](https://github.com/aws/amazon-freertos/tree/master/libraries/c_sdk) to allow you to use the latest version with your current API calls. For the move to the latest MQTT, I can provide some information on equivalent structures and functions for the move from the older MQTT API (v4 of the Embedded C SDK) to the current one: ## Removed Features: - **Taskpool** Version 4 uses a taskpool for scheduling MQTT operations in the background. Version 202011.00 and subsequent releases do not spawn any threads and have no need for a taskpool. - **Thread support** Version 4 relies on a platform’s threading capabilities for multi-threading use cases. Version 202011.00 and subsequent releases do not spawn any threads and therefore, do not require the use of a platform’s multithreading. If threading support or connection sharing is desired, please see our connection sharing demo for an example of using the MQTT library in a multithreaded environment. ## Data Types: | Version 4 | Version 202011.00 and subsequent releases | Notes | | --- | --- | --- | | IotMqttQos\_t | MQTTQoS\_t | MQTT Quality of service. | | IotMqttError\_t | MQTTStatus\_t | Return codes of API functions. | | IotMqttConnection\_t | MQTTContext\_t | MQTT connection handle. | | IotMqttPublishInfo\_t | MQTTPublishInfo\_t | Parameters of an MQTT publish. | | IotMqttConnectInfo\_t | MQTTConnectInfo\_t | Parameters of an MQTT connect. | | IotMqttSubscription\_t | _None_ | Version 202011.00 and subsequent releases leave subscription tracking to the application. | | IotMqttPacketInfo\_t | MQTTPacketInfo\_t MQTTDeserializedInfo\_t | Deserialized MQTT Packet information. | | IotMqttCallbackInfo\_t | MQTTEventCallback\_t | Function pointer of application callback to receive incoming data. | ## Functions: | Version 4 | Version 202011.00 and subsequent releases | Notes | | --- | --- | --- | | IotMqtt\_Init | [MQTT\_Init](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#ae8444f3a85535e62cdb1ae9c192677d6) | In v4, this function initializes the entire library. In 202011.00 and subsequent releases, it initializes a single client. | | IotMqtt\_Cleanup | _None_ | 202011.00 and subsequent releases does not allocate any memory and therefore, has nothing to free. | | IotMqtt\_Connect | [MQTT\_Connect](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#aed1e4dc123a8ba79ac569cb17c69bfa0) | | | IotMqtt\_PublishAsync IotMqtt\_PublishSync | [MQTT\_Publish](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#a1d8217e9d30fb2aed002060a8c97c63e) | From the perspective of the v4 library, all of version 202011.00’s publishes are asynchronous. To receive any expected acknowledgment packet, [MQTT\_ProcessLoop](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#adce9111350db412c1256689ef9a7b9f4) must be called. | | IotMqtt\_SubscribeAsync IotMqtt\_SubscribeSync | [MQTT\_Subscribe](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#a567aa9c38726a7879f9cbf943e813e8f) | From the perspective of the v4 library, all of version 202011.00’s subscribe operations are asynchronous. To receive the acknowledgment packet, [MQTT\_ProcessLoop](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#adce9111350db412c1256689ef9a7b9f4) must be called. | | IotMqtt\_UnsubscribeAsync IotMqtt\_UnsubscribeSync | [MQTT\_Unsubscribe](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#a77c911dbe24c5a51aaea88250895dba4) | From the perspective of the v4 library, all of version 202011.00’s unsubscribe operations are asynchronous. To receive the acknowledgment packet, [MQTT\_ProcessLoop](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#adce9111350db412c1256689ef9a7b9f4) must be called. | | IotMqtt\_Disconnect | [MQTT\_Disconnect](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#ac79c366acbc3dddd88072d99ccb9140c) | | | _None_ | [MQTT\_ProcessLoop](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#adce9111350db412c1256689ef9a7b9f4) | [MQTT\_ReceiveLoop](https://docs.aws.amazon.com/embedded-csdk/202012.00/lib-ref/libraries/standard/coreMQTT/docs/doxygen/output/html/core__mqtt_8c.html#a274d7a62c9c011a063031c2e678fb40a) is the equivalent function without any keep-alive mechanism. | Let us know if you need any further assistance in migrating to the latest version --- _[View the full topic](https://forums.freertos.org/t/is-there-a-porting-guide-from-older-version-202002-and-201906-to-the-last-one-202012/11383)._