Why getClientInstance is used for inbound and getAsyncClientInstance is used for outbound to get synchronous and asynchronous clients.

[qq2429979710]

What if I use an asynchronous client for both outbound and inbound, I see that the code is private and there is no way to rewrite it

this.client = this.clientFactory.getAsyncClientInstance(this.getUrl(), this.getClientId());

[garyrussell]

It is not clear what you mean; please elaborate.

We use the async client in all places.

It will block (outbound) to wait for the result, unless you set async to true.

[qq2429979710]

Here is the code snippet：

MqttPahoClientFactory     interface

	IMqttClient getClientInstance(String url, String clientId) throws MqttException;

	IMqttAsyncClient getAsyncClientInstance(String url, String clientId) throws MqttException;

Inbound：
  connectAndSubscribe   method
  this.client = this.clientFactory.getClientInstance(getUrl(), getClientId());
Outbound：
  checkConnection  method
  this.client = this.clientFactory.getAsyncClientInstance(this.getUrl(), this.getClientId());

I see different clients used for inbound and outbound creation clients

What I want to do is to make sure that the inbound and outbound are using the same client by rewriting MqttPahoClientFactory to get the client, but I can cache it against the HashMap

like this :

   private Map<String,IMqttAsyncClient> iMqttAsyncClientMap = new ConcurrentHashMap<>();
    @Override
    public IMqttAsyncClient getAsyncClientInstance(String uri, String clientId) throws MqttException {
        String key = uri + clientId;
        IMqttAsyncClient iMqttAsyncClient = iMqttAsyncClientMap.get(key);
        if(iMqttAsyncClient==null){
            iMqttAsyncClient= super.getAsyncClientInstance(uri, clientId);
            iMqttAsyncClientMap.put(key,iMqttAsyncClient);
        }
        return iMqttAsyncClient;
    }

However, I found that the inbound and outbound terminals were not the same client, so my idea could not be implemented

[garyrussell]

There is a recent (merged) pull request for sharing clients across components spring-projects/spring-integration#3857 for the upcoming 6.0 release.

In previous versions, a sync Vs. async made no different on the inbound side.

[qq2429979710]

Ok, my requirement is to use the same clientID client and push and subscribe.

[artembilan]

Right, we didn't support shared client between channel adapter until the fix Gary has shared with you.

It is probably possible to implement a custom MqttPahoClientFactory to return the same client for every getAsyncClientInstance() call.
The getClientInstance() can return a custom (and same) IMqttClient which can delegate to respective IMqttAsyncClient. That's essentially what is going on in the org.eclipse.paho.client.mqttv3.MqttClient.

I'm treating this issue as Invalid since this project is not about asking questions.
Ask them on StackOverflow, please.