Solace PubSub+ Connector in Mulesoft number of connections used

Connectors & Integrations
1

Hello team,

I have some questions about how connections are counted using MuleSoft Solace connector. Our context is the following: we have MuleSoft connecting to a SAP AEM tenant of 250 client connections (AEM Service Class Broker 250).

Reference: Service Class Options for Event Broker Services

Assumption 1: Service-Level Limits for Each Service Class

As Solace counts connections based on the number of active, unique TCP socket connections (sessions) between the MuleSoft runtime and the Solace broker. Each MuleSoft connector configuration will create a distinct session, meaning that for each application in MuleSoft with one single worker/replica/node will consume one single client connection, allowing multiple subscribers/publishers to share it. If we add more workers to the application, that will consume additional client connections.

For example: one MuleSoft application with 2 workers/replicas will consume 2 client connections.

Assumption 2: Service-Level Limits for Flows and Transactions

For each client connection we can have at most 250 consumers and/or 250 producers running in parallel.

Are our assumptions correct?

Thanks.

Best Regards.

Pedro.

2

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The documentation doesn’t provide specific details about how the MuleSoft Solace connector internally manages sessions or whether each connector configuration creates a distinct session. However, the available information does shed some light on the broader connection counting model.

On connection counting generally:

From the Solace Event Broker perspective, each messaging client (SMF, MQTT, AMQP, or REST) counts as 1 connection against the max-connections limit — regardless of how many flows, consumers, or producers are multiplexed over that connection. A single application can open one connection to the event broker and bind to the same queue multiple times (these are called “egress flows” in Solace terminology), and that still counts as just 1 connection. Alternatively, if each worker/replica establishes its own independent connection to the event broker, each would count as a separate connection.

So whether adding more MuleSoft workers/replicas consumes additional client connections depends entirely on how the MuleSoft Solace connector manages its underlying sessions — which is not definitively documented in the available sources.

On the 250 consumers/producers limit:

The “250” figure you mention appears to relate to the service class limits in Solace Cloud (e.g., the Enterprise 250 service class has 250 incoming flows and 250 outgoing flows). This is a system-wide limit on the event broker service, not a per-connection limit. There is no documentation in the available sources confirming a hard limit of 250 consumers or producers per individual client connection.

On multiple consumers in the MuleSoft Solace connector:

It’s worth noting that as of early 2025, multiple consumer support within a single MuleSoft Solace connector flow is not supported. The recommended workaround is to run multiple flows consuming from the same partitioned queue.

For authoritative details on connection counting and flow limits, these sources are relevant:

3

Sorry, I don’t think that is clarifying my doubts.

Best Regards.

4

Is it possible that somebody from the product team can answer if our assumptions are correct? Thanks!

5

Hi, I am an integration PLM at Solace.

Assumption 1

This is somewhat true, workers will multiply your used connections to the broker by the number of workers. So yes, add more workers means that many more connections. But the number of connections per MuleSoft “application” will depend on how many Solace connector operations (like Guaranteed Endpoint Listeners or Publish, etc.). Each operation will be a connection. So, if you have several flows in the app and several Solace connector operations, it would be:

  • total # of Solace operations x workers = total connections used by MuleSoft app

Assumption 2

Yes, but the total number available to your MuleSoft app will be somewhat lower than 250. Users who connect to the web interface of Broker Manager, config-sync, etc. also use connections if configured.

The posted limits in the tables below refer to the latest version supported on advanced event mesh. Event broker services utilize a varying number of internal topic subscriptions, clients, queues, and connections based on the configuration of these features:

  • Config-Sync

  • Clusters and event mesh (DMR)

  • Disaster Recovery (DR) using Replication

  • VPN Bridges

So, it might not be 250 available to the MuleSoft app.

6

Hi @amackenzie ,

Thanks for your feedback. What we have noticed is that if we have 4 flows publishing messages to some queues, and at the same time 4 flows listening to those queues, just one single SMF client connection is consumed, we can see 4 active consumers associated to the same SMF client.

As soon as we increase the replicas of our MuleSoft app, we can see that as MuleSoft is using a new IP, a new SMF Client connection is created and consumed.

Therefore, our assumption is that client connection limit is linked to MuleSoft replicas/nodes IPs. It is not related with the number of lows or operations we are performing, because within the same node of an application all them are sharing the same TCP connection.

So when you have commented “total # of Solace operations x workers = total connections used by MuleSoft app” are you referring to consumed SMF client connections? Because we cannot see exactly that in our tests.

It more something like:

workers = SMF Client connections

total# of solace operations = consumers/producers linked to an SMF client connection.

Best Regards.

Pedro.