PostgreSQL is a completely community-driven open source project, maintained by more than 1,000 contributors worldwide. PostgreSQL provides a single full-featured version, that is unlike MySQL which offers multiple different versions for community, business, and enterprise. PostgreSQL is based on a free BSD / MIT license, and organizations can use, copy, modify, and redistribute its code with a copyright notice.
In Internet applications, message queues are generally integrated to perform operations such as peak clipping, current limiting, and queue processing to decouple data from services. With the help of RabbitMQ, Kafka, RocketMQ, Pulsar and other message and stream middleware bridging functions provided by EMQ X, IoT projects can also use this model to solve the above problems.
OpenTSDB is an extensible distributed time series Database database, whose bottom layer relies on HBase and makes full use of HBase's features of distributed column storage to support millions of reads and writes per second.
TDengine is an open source big data platform designed and optimized for Internet of Things, Internet of Vehicles, Industrial Internet, IT operation and maintenance, etc., launched by TAOS Data (Beijing TAOS Data Technology Co., Ltd.). In addition to the core timing database functions that are more than 10 times faster, it also provides functions such as caching, data subscription, and streaming computing to minimize the complexity of R & D, operation and maintenance.
This example will demonstrate how to report the temperature and humidity data collected by the DHT11 sensor to the MQTT service in the cloud through the MQTT protocol and the NodeMCU based on ESP8266 , and show how the application subscribes to and processes the data.
MQTT 5.0 Clean Start and Session Expiry Interval not only solve the legacy problems of Clean Session, but also extend the usage scenarios of the client.