C++, Max clients exceeded for queue

PubSub+ Event Broker
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1

Hi,

I would like to send Guaranteed messages to a queue and then read them back within a C++ project.

I have managed to create a session (solClient_session_create), then I created a transacted session (solClient_session_createTransactedSession). When creating a flow (solClient_transactedSession_createFlow), I get the following error

  • ReturnCode=Fail
  • SubCode=SOLCLIENT_SUBCODE_MAX_CLIENTS_FOR_QUEUE
  • ResponseCode=503
  • Info=Max clients exceeded for queue
SOLACE_RET_CODE_CHK(solClient_session_createTransactedSession(nullptr, this->m_SolSession, &this->m_transacted_session, nullptr));

solClient_flow_createFuncInfo_t function_info = SOLCLIENT_SESSION_CREATEFUNC_INITIALIZER;
function_info.rxMsgInfo.callback_p = nullptr;
function_info.rxMsgInfo.user_p = nullptr;
function_info.eventInfo.callback_p = common_flow_event_callback;

auto index = 0;
char* flow_properties[10];

flow_properties[index++] = SOLCLIENT_FLOW_PROP_BIND_BLOCKING;
flow_properties[index++] = SOLCLIENT_PROP_ENABLE_VAL;

flow_properties[index++] = SOLCLIENT_FLOW_PROP_BIND_ENTITY_ID;
flow_properties[index++] = SOLCLIENT_FLOW_PROP_BIND_ENTITY_QUEUE;

flow_properties[index++] = SOLCLIENT_FLOW_PROP_BIND_NAME;
flow_properties[index++] = "MY_QUEUE"

flow_properties[index++] = SOLCLIENT_FLOW_PROP_BIND_ENTITY_DURABLE;
flow_properties[index++] = SOLCLIENT_PROP_ENABLE_VAL;

flow_properties[index] = nullptr;

SOLACE_RET_CODE_CHK(solClient_transactedSession_createFlow(flow_properties, this->m_transacted_session, &this->m_flow, &function_info, sizeof(function_info)));

I would like to create one transacted session and flow for a “writer” and the same session and flow for a “reader”. Do you happen to know why I get the error?

I have got an access to a web portal where I can configure VPNs and queues.

Thank you, Martin.

2

Hi @martinpelak,

Have you enabled transacted session permissions in your client profile? Have a look in PubSub+ Manager → → Access Control → Client Profiles → default → Settings and look for “Use Transacted Sessions”.

Also, please change
function_info.rxMsgInfo.callback_p = nullptr;
to something non null. It’s where your messages will be received.

3

Hi,

Thank you. I enabled it before posting my question. I use solClient_flow_receiveMsg to receive messages.

Thank you, Martin.

4

OK, good. I assume you’ve set the Maximum Consumer Count to greater than 0?

solClient_flow_receiveMsg will receive messages for your flow (= queue).

rxMsgInfo.callback_p is for an direct (non-queued) messages. For testing code it’s probably fine if you’re not subscribing to anything, but please don’t go in to prod with that set to null.

5

Thank you. The Maximum Consumer Count is set to 1000.

So you suggest that I set rxMsgInfo.callback_p to anything even though I plan on using just solClient_flow_receiveMsg to receive messages? I noticed that in this example, the callback is set to null as well. Would an empty function be ok?

solClient_rxMsgCallback_returnCode_t rx_message_flow_callback(solClient_opaqueFlow_pt opaque_flow, solClient_opaqueMsg_pt message, void* user)
{
    return SOLCLIENT_CALLBACK_OK;
}

I am quite new to Solace so any piece of advice is appreciated.

6

Hmm. This error is definitely related to the number of connections being exhausted somewhere. Can you check the Message VPN and system maximum connection counts?

The callback comment is a bit of diversion - I see it as best practice to not have it set to NULL.