Selecting Partition of Azure event hub when using

Question

I'm trying to send messages to Azure Event Hub using python and the rest API after some failed experiments i have found working code (see below) but i want to be able to select to which partition to send the event.

Is this possible using the rest API and if so how should be done?

#!/user/bin/python
import json
from datetime import datetime
from multiprocessing import Pool
# from azure.servicebus import _service_bus_error_handler

from azure.servicebus.servicebusservice import ServiceBusService, ServiceBusSASAuthentication

from azure.http import (
    HTTPRequest,
    HTTPError
)

from azure.http.httpclient import _HTTPClient

EVENT_HUB_HOST = "mysecrethub.servicebus.windows.net"
EVENT_HUB_NAME = "secerthub-name"
KEYNAME = "senderkey"  # needs to be loaded from ENV
KEYVALUE = "keyvalue"  # needs to be loaded from ENV
EXTRA_HEADERS = []
NUM_OF_PARTITIONS = 16


class EventHubClient(object):

    def __init__(self, host, hubname, keyname, keyvalue):
        self._host = host
        self._hub = hubname
        self._keyname = keyname
        self._key = keyvalue

    def sendMessage(self, body, partition=None, additional_headers=None):
        eventHubHost = self._host

        httpclient = _HTTPClient(service_instance=self)

        sasKeyName = self._keyname
        sasKeyValue = self._key

        authentication = ServiceBusSASAuthentication(sasKeyName, sasKeyValue)

        request = HTTPRequest()
        request.method = "POST"
        request.host = eventHubHost
        request.protocol_override = "https"
        request.path = "/%s/messages?api-version=2014-01" % (self._hub)
        request.body = body
        request.headers.append(('Content-Type', 'application/atom+xml;type=entry;charset=utf-8'))
        if additional_headers is not None:
            for item in additional_headers:
                request.headers.append(item)
        if partition is not None:
            value = json.dumps({'PartitionKey': partition})
            request.headers.append(('BrokerProperties', value))
        authentication.sign_request(request, httpclient)

        request.headers.append(('Content-Length', str(len(request.body))))

        status = 0

        try:
            resp = httpclient.perform_request(request)
            status = resp.status
        except HTTPError as ex:
            status = ex.status
        # print request.headers
        return status


def prepare_message(appid, sessionid, partitionKey=None, SessionEllapsed=None, DeviceOs=None):
    message = {"Name": "MonitorEvent"}
    Attributes = {"AppId": appid, "SessionStarted": "".join(str(datetime.now())[:-3])}
    if SessionEllapsed is not None:
        Attributes['SessionEllapsed'] = SessionEllapsed
    if DeviceOs is not None:
        Attributes['DeviceOs'] = DeviceOs
    if partitionKey is not None:
        message["PartitionKey"] = str(partitionKey)
        message["PartitionId"] = str(partitionKey)
        Attributes['ItemId'] = partitionKey
    message['Attributes'] = Attributes
    return json.dumps(message)


def send_monitoring_event(partition):
    hubClient = EventHubClient(EVENT_HUB_HOST, EVENT_HUB_NAME, KEYNAME, KEYVALUE)
    appid = 1
    sendertime = datetime.now().strftime('%Y%M%d-%H%M%S')
    message = prepare_message(appid, sendertime, partitionKey=partition, SessionEllapsed=1, DeviceOs='Monitor' + str(partition))
    # print message
    hubStatus = hubClient.sendMessage(message, partition=None, additional_headers=EXTRA_HEADERS)
# return the HTTP status to the caller
    return hubStatus


def main():
    pool = Pool(processes=NUM_OF_PARTITIONS)

    print pool.map(send_monitoring_event, range(NUM_OF_PARTITIONS))

if __name__ == '__main__':
    main()

Answer 1

Following the section 'Send Event' of Event Hubs REST APIs docunment https://msdn.microsoft.com/en-us/library/azure/dn790664.aspx, you can't use the Request URI https://{serviceNamespace}.servicebus.windows.net/{eventHubPath}/messages to select to which partition to send events.

You should use the Request URI https://{serviceNamespace}.servicebus.windows.net/{eventHubPath}/publishers/{deviceId}/messages. The attribute {deviceId} is partition key what used to group/partition devices—whether it is geo-location, device type, version, tenant, and so on.

But the partition count must be a number between 2 and 32. So if you need to use more than 32 partitions, I suggest to put the key into the event data.

Best Regards.