Trying to publish a message through AMQP via the r...

# kotlin-native

[napperley]

Trying to publish a message through AMQP via the rabbitmq-c library ( https://github.com/alanxz/rabbitmq-c ), and it looks as though the message isn't getting through (the Broker has dropped the message). The amqp_basic_publish function is returning 0 (this means the message has been successfully transmitted to the Broker). Below is the code that is being used to publish the message:

private fun publishMessage(conn: amqp_connection_state_t?) = memScoped {
    val props = alloc<amqp_basic_properties_t>()
    with(props) {
        _flags = (AMQP_BASIC_CONTENT_TYPE_FLAG or AMQP_BASIC_DELIVERY_MODE_FLAG).toUInt()
        // TODO: Figure out how to set the AMQP content type.
//        content_type = amqp_cstring_bytes("text/plain")
        // Persistent delivery mode.
        delivery_mode = 2.toUByte()
    }
    println("Publishing message...")
    val publishRc = amqp_basic_publish(
        state = conn,
        channel = channel,
        exchange = amqp_cstring_bytes(EXCHANGE),
        routing_key = amqp_cstring_bytes(ROUTING_KEY),
        mandatory = 0,
        immediate = 0,
        properties = props.ptr,
        body = amqp_cstring_bytes(MSG_BODY)
    )
    if (publishRc != 0) println("Cannot publish message.")
    Unit
}

[napperley]

After looking through the Broker log I found that the message was dropped because the exchange is incorrect:

operation basic.publish caused a channel exception not_found: no exchange 'ø' in vhost '/'

As I suspected there is something strange going on with the String handling.

[napperley]

The exchange is set to amq.topic (this exchange exists in the Broker) in the program however the library turns it into ø (in a terminal it is displayed as a square), which causes the message to be dropped by the Broker.

[napperley]

All strings that are passed to the amqp_basic_publish function must be converted to amqp_bytes_t. The amqp_cstring_bytes function is used to convert a string to amqp_bytes_t.

[napperley]

Below is the mapping for the amqp_cstring_bytes function:

@kotlinx.cinterop.internal.CCall public external fun amqp_cstring_bytes(@kotlinx.cinterop.internal.CCall.CString cstr: kotlin.String?): kotlinx.cinterop.CValue<amqpClient.amqp_bytes_t /* = amqpClient.amqp_bytes_t_ */>