Step 4: Connect to a RocketMQ Instance to Create and Retrieve Messages

This section describes how to use TCP to connect to a RocketMQ instance with SSL in CLI mode.

Prerequisites

A RocketMQ instance has been created following the instructions in Step 2: Create a RocketMQ Instance, and the instance addresses have been recorded.
Security group rules have been configured.
A topic has been created and you have obtained the topic name.
An ECS has been created. For intra-VPC access, ensure that its VPC, subnet, and security group configurations are the same as those of the RocketMQ instance.
You have installed the JDK and configured the environment variables. For details, see Step 1: Prepare the Environment.

Accessing the Instance with CLI

Download the rocketmq-tutorial software package.

wget https://dms-demo.obs.cn-north-1.myhuaweicloud.com/rocketmq-tutorial.zip

Decompress the rocketmq-tutorial package.
```
unzip rocketmq-tutorial.zip
```
Go to the rocketmq-tutorial/bin directory.
```
cd rocketmq-tutorial/bin
```
Create normal messages using the sample project.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin sendMessage -n "${Connection addresses}" -t ${Topic name} -p "hello rocketmq"
```
Parameter description:
- Connection addresses: the RocketMQ instance address.
- Topic name: name of the topic created for the RocketMQ instance
In the following example, 100.xxx.xxx.89:8200;100.xxx.xxx.144:8200 are the connection addresses to the RocketMQ instance, and topic-test is the topic name.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin sendMessage -n "100.xxx.xxx.89:8200;100.xxx.xxx.144:8200" -t topic-test -p "hello rocketmq"
```
Press Ctrl+C to exit.
Retrieve normal messages using the sample project.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin consumeMessage -n "${Connection addresses}" -t ${Topic name}
```
Parameter description:
- Connection addresses: the RocketMQ instance address.
- Topic name: name of the topic created for the RocketMQ instance
In the following example, 100.xxx.xxx.89:8200;100.xxx.xxx.144:8200 are the connection addresses to the RocketMQ instance, and topic-test is the topic name.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin consumeMessage -n "100.xxx.xxx.89:8200;100.xxx.xxx.144:8200" -t topic-test
```
To stop consuming messages, press Ctrl+C to exit.
Create messages with traces using the sample project.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin sendMessage -n "${Connection addresses}" -t ${Topic name} -p "hello rocketmq" -m true
```
Parameter description:
- Connection addresses: the RocketMQ instance address.
- Topic name: name of the topic created for the RocketMQ instance
In the following example, 100.xxx.xxx.89:8200;100.xxx.xxx.144:8200 are the connection addresses to the RocketMQ instance, and topic-test is the topic name.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin sendMessage -n "100.xxx.xxx.89:8200;100.xxx.xxx.144:8200" -t topic-test -p "hello rocketmq" -m true
```
Press Ctrl+C to exit.
Retrieve messages and send the message traces using the sample project.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin consumeMessage -n "${Connection addresses}" -t ${Topic name} -m true
```
Parameter description:
- Connection addresses: the RocketMQ instance address.
- Topic name: name of the topic created for the RocketMQ instance
In the following example, 100.xxx.xxx.89:8200;100.xxx.xxx.144:8200 are the connection addresses to the RocketMQ instance, and topic-test is the topic name.
```
JAVA_OPT=-Dtls.enable=true sh mqadmin consumeMessage -n "100.xxx.xxx.89:8200;100.xxx.xxx.144:8200" -t topic-test -m true
```
Press Ctrl+C to exit.