class MailService(object):
"""
Mail Service class.
"""
def __init__(self):
self.consumers = Consumers('mail-service', [self.send])
self.event_store = EventStoreClient()
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
self.consumers.stop()
logging.info('stopped.')
def send(self, _req):
if not _req['to'] or not _req['msg']:
return {"error": "missing mandatory parameter 'to' and/or 'msg'"}
# trigger event
self.event_store.publish(
'mail',
create_event('mail_sent', {
"recipient": _req['to'],
"message": _req['msg']
}))
class CustomerService(object):
"""
Customer Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers('customer-service', [
self.create_customers, self.update_customer, self.delete_customer
])
@staticmethod
def _create_entity(_name, _email):
"""
Create a customer entity.
:param _name: The name of the customer.
:param _email: The em2ail address of the customer.
:return: A dict with the entity properties.
"""
return {'entity_id': str(uuid.uuid4()), 'name': _name, 'email': _email}
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
self.consumers.stop()
logging.info('stopped.')
def create_customers(self, _req):
customers = _req if isinstance(_req, list) else [_req]
customer_ids = []
for customer in customers:
try:
new_customer = CustomerService._create_entity(
customer['name'], customer['email'])
except KeyError:
return {
"error":
"missing mandatory parameter 'name' and/or 'email'"
}
# trigger event
self.event_store.publish(
'customer', create_event('entity_created', new_customer))
customer_ids.append(new_customer['entity_id'])
return {"result": customer_ids}
def update_customer(self, _req):
try:
customer = CustomerService._create_entity(_req['name'],
_req['email'])
except KeyError:
return {
"error": "missing mandatory parameter 'name' and/or 'email'"
}
try:
customer['entity_id'] = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
# trigger event
self.event_store.publish('customer',
create_event('entity_updated', customer))
return {"result": True}
def delete_customer(self, _req):
try:
customer_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'customer',
'id': customer_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
customer = rsp['result']
if not customer:
return {"error": "could not find customer"}
# trigger event
self.event_store.publish('customer',
create_event('entity_deleted', customer))
return {"result": True}
class BillingService(object):
"""
Billing Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers('billing-service', [self.create_billings,
self.update_billing,
self.delete_billing])
@staticmethod
def _create_entity(_order_id, _amount):
"""
Create a billing entity.
:param _order_id: The order ID the billing belongs to.
:param _amount: Total amount to pay.
:return: A dict with the entity properties.
"""
return {
'entity_id': str(uuid.uuid4()),
'order_id': _order_id,
'amount': _amount
}
@staticmethod
def _check_amount(_billing):
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': _billing['order_id']})
order = rsp['result']
rsp = send_message('read-model', 'get_entity', {'name': 'cart', 'id': order['cart_id']})
cart = rsp['result']
rsp = send_message('read-model', 'get_entities', {'name': 'product', 'ids': cart['product_ids']})
products = rsp['result']
amount = sum([int(product['price']) for product in products])
return amount == int(_billing['amount'])
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
self.consumers.stop()
logging.info('stopped.')
def create_billings(self, _req):
billings = _req if isinstance(_req, list) else [_req]
billing_ids = []
for billing in billings:
res = self._check_amount(billing)
if not res:
return {
'error': 'amount is not accurate'
}
try:
new_billing = BillingService._create_entity(billing['order_id'], billing['amount'])
except KeyError:
return {
"error": "missing mandatory parameter 'order_id' and/or 'amount'"
}
# trigger event
self.event_store.publish('billing', create_event('entity_created', new_billing))
billing_ids.append(new_billing['entity_id'])
return {
"result": billing_ids
}
def update_billing(self, _req):
try:
billing_id = _req['entity_id']
except KeyError:
return {
"error": "missing mandatory parameter 'entity_id'"
}
rsp = send_message('read-model', 'get_entitiy', {'name': 'billing', 'id': billing_id})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
billing = rsp['result']
if not billing:
return {
"error": "could not find billing"
}
# set new props
billing['entity_id'] = billing_id
try:
billing['order_id'] = _req['order_id']
billing['amount'] = _req['amount']
except KeyError:
return {
"result": "missing mandatory parameter 'order_id' and/or 'amount"
}
res = self._check_amount(billing)
if not res:
return {
'error': 'amount is not accurate'
}
# trigger event
self.event_store.publish('billing', create_event('entity_updated', billing))
return {
"result": True
}
def delete_billing(self, _req):
try:
billing_id = _req['entity_id']
except KeyError:
return {
"error": "missing mandatory parameter 'entity_id'"
}
rsp = send_message('read-model', 'get_entitiy', {'name': 'billing', 'id': billing_id})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
billing = rsp['result']
if not billing:
return {
"error": "could not find billing"
}
# trigger event
self.event_store.publish('billing', create_event('entity_deleted', billing))
return {
"result": True
}
class ReadModel(object):
"""
Read Model class.
"""
def __init__(self, _redis_host='localhost', _redis_port=6379):
self.event_store = EventStoreClient()
self.consumers = Consumers('read-model', [self.get_entity,
self.get_entities,
self.get_mails,
self.get_unbilled_orders,
self.get_unshipped_orders,
self.get_delivered_orders])
self.domain_model = DomainModel(
redis.StrictRedis(host=_redis_host, port=_redis_port, decode_responses=True)
)
self.subscriptions = {}
self.locks = {}
@staticmethod
def _deduce_entities(_events):
"""
Deduce entities from events.
:param _events: A list with events.
:return: A dict mapping entity ID -> entity data.
"""
if not _events:
return {}
# find 'created' events
result = {json.loads(e[1]['event_data'])['entity_id']: json.loads(e[1]['event_data'])
for e in filter(lambda x: x[1]['event_action'] == 'entity_created', _events)}
# remove 'deleted' events
deleted = {json.loads(e[1]['event_data'])['entity_id']: json.loads(e[1]['event_data'])
for e in filter(lambda x: x[1]['event_action'] == 'entity_deleted', _events)}
for d_id, d_data in deleted.items():
del result[d_id]
# change 'updated' events
updated = {json.loads(e[1]['event_data'])['entity_id']: json.loads(e[1]['event_data'])
for e in filter(lambda x: x[1]['event_action'] == 'entity_updated', _events)}
for u_id, u_data in updated.items():
result[u_id] = u_data
return result
def _track_entities(self, _name, _event):
"""
Keep track of entity events.
:param _name: The entity name.
:param _event: The event data.
"""
if not self.domain_model.exists(_name):
return
entity = json.loads(_event.event_data)
if _event.event_action == 'entity_created':
self.domain_model.create(_name, entity)
if _event.event_action == 'entity_deleted':
self.domain_model.delete(_name, entity)
if _event.event_action == 'entity_updated':
self.domain_model.update(_name, entity)
def _query_entities(self, _name):
"""
Query all entities of a given name.
:param _name: The entity name.
:return: A dict mapping entity ID -> entity.
"""
entities = self.domain_model.retrieve(_name)
if entities:
return entities
if _name not in self.locks:
self.locks[_name] = threading.Lock()
with self.locks[_name]:
entities = self.domain_model.retrieve(_name)
if entities:
return entities
# deduce entities
events = self.event_store.get(_name)
entities = self._deduce_entities(events)
# cache entities
for entity in entities.values():
self.domain_model.create(_name, entity)
# track entities
tracking_handler = functools.partial(self._track_entities, _name)
self.event_store.subscribe(_name, tracking_handler)
self.subscriptions[_name] = tracking_handler
return entities
def _query_defined_entities(self, _name, _props):
"""
Query entities with defined properities.
:param _name: The entity name.
:param _props: A dict mapping property name -> property value(s).
:return: A dict mapping entity ID -> entity.
"""
result = {}
for entity_id, entity in self._query_entities(_name).items():
for prop_name, prop_value in _props.items():
if not isinstance(prop_value, list):
prop_value = [prop_value]
if prop_name in entity and entity[prop_name] in prop_value:
result[entity_id] = entity
return result
def _unbilled_orders(self):
"""
Query all unbilled orders, i.e. orders w/o corresponding billing.
:return: a dict mapping entity ID -> entity.
"""
orders = self._query_entities('order')
billings = self._query_entities('billing')
unbilled = orders.copy()
for billing_id, billing in billings.items():
order_ids_to_remove = list(filter(lambda x: x == billing['order_id'], orders))
if not order_ids_to_remove:
raise Exception(f'could not find order {billing["order_id"]} for billing {billing_id}')
if order_ids_to_remove[0] not in unbilled:
raise Exception(f'could not find order {order_ids_to_remove[0]}')
del unbilled[order_ids_to_remove[0]]
return unbilled
def _unshipped_orders(self):
"""
Query all unshipped orders, i.e. orders w/o corresponding shipping done.
:return: a dict mapping entity ID -> entity.
"""
orders = self._query_entities('order')
shippings = self._query_entities('shipping')
unshipped = orders.copy()
for shipping_id, shippings in shippings.items():
order_ids_to_remove = list(filter(lambda x: x == shippings['order_id'], orders))
if not order_ids_to_remove:
raise Exception(f'could not find order {shippings["order_id"]} for shipping {shipping_id}')
if order_ids_to_remove[0] not in unshipped:
raise Exception(f'could not find order {order_ids_to_remove[0]}')
del unshipped[order_ids_to_remove[0]]
return unshipped
def _delivered_orders(self):
"""
Query all delivered orders.
:return: a dict mapping entity ID -> entity.
"""
shippings = self._query_entities('shipping')
return list(filter(lambda x: x['delivered'], shippings.values()))
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
for name, handler in self.subscriptions.items():
self.event_store.unsubscribe(name, handler)
self.consumers.stop()
logging.info('stopped.')
def get_entity(self, _req):
if 'name' not in _req:
return {
"error": "missing mandatory parameter 'name'"
}
if 'id' in _req:
return {
'result': self._query_entities(_req['name']).get(_req['id'])
}
elif 'props' in _req and isinstance(_req['props'], dict):
result = list(self._query_defined_entities(_req['name'], _req['props']).values())
if len(result) <= 1:
return {
'result': result[0] if result else None
}
else:
return {
'error': 'more than 1 result found'
}
else:
return {
'result': 'invalid parameters'
}
def get_entities(self, _req):
if 'name' not in _req:
return {
"error": "missing mandatory parameter 'name'"
}
elif 'ids' in _req and isinstance(_req['ids'], list):
return {
'result': [self._query_entities(_req['name']).get(_id) for _id in _req['ids']]
}
elif 'props' in _req and isinstance(_req['props'], dict):
return {
'result': list(self._query_defined_entities(_req['name'], _req['props']).values())
}
else:
return {
'result': list(self._query_entities(_req['name']).values())
}
def get_mails(self, _req):
return {
'result': self.event_store.get('mail') or []
}
def get_unbilled_orders(self, _req):
return {
'result': self._unbilled_orders()
}
def get_unshipped_orders(self, _req):
return {
'result': self._unshipped_orders()
}
def get_delivered_orders(self, _req):
return {
'result': self._delivered_orders()
}
class ProductService(object):
"""
Product Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers(
'product-service',
[self.create_products, self.update_product, self.delete_product])
@staticmethod
def _create_entity(_name, _price):
"""
Create a product entity.
:param _name: The name of the product.
:param _price: The price of the product.
:return: A dict with the entity properties.
"""
return {'entity_id': str(uuid.uuid4()), 'name': _name, 'price': _price}
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
self.consumers.stop()
logging.info('stopped.')
def create_products(self, _req):
products = _req if isinstance(_req, list) else [_req]
product_ids = []
for product in products:
try:
new_product = ProductService._create_entity(
product['name'], product['price'])
except KeyError:
return {
"error":
"missing mandatory parameter 'name' and/or 'price'"
}
# trigger event
self.event_store.publish(
'product', create_event('entity_created', new_product))
product_ids.append(new_product['entity_id'])
return {"result": product_ids}
def update_product(self, _req):
try:
product_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'product',
'id': product_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
product = rsp['result']
if not product:
return {"error": "could not find product"}
# set new props
product['entity_id'] = product_id
try:
product['name'] = _req['name']
product['price'] = _req['price']
except KeyError:
return {
"result": "missing mandatory parameter 'name' and/or 'price"
}
# trigger event
self.event_store.publish('product',
create_event('entity_updated', product))
return {"result": True}
def delete_product(self, _req):
try:
product_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'product',
'id': product_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
product = rsp['result']
if not product:
return {"error": "could not find product"}
# trigger event
self.event_store.publish('product',
create_event('entity_deleted', product))
return {"result": True}
class OrderService(object):
"""
Order Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers('order-service', [self.create_orders,
self.update_order,
self.delete_order])
@staticmethod
def _create_entity(_cart_id, _status='CREATED'):
"""
Create an order entity.
:param _cart_id: The cart ID the order is for.
:param _status: The current status of the order, defaults to CREATED.
Other options are OUT_OF_STOCK, IN_STOCK, CLEARED, UNCLEARED, SHIPPED and DELIVERED.
:return: A dict with the entity properties.
"""
return {
'entity_id': str(uuid.uuid4()),
'cart_id': _cart_id,
'status': _status,
}
def start(self):
logging.info('starting ...')
self.event_store.subscribe('billing', self.billing_created)
self.event_store.subscribe('billing', self.billing_deleted)
self.event_store.subscribe('shipping', self.shipping_created)
self.event_store.subscribe('shipping', self.shipping_updated)
self.consumers.start()
self.consumers.wait()
def stop(self):
self.event_store.unsubscribe('billing', self.billing_created)
self.event_store.unsubscribe('billing', self.billing_deleted)
self.event_store.unsubscribe('shipping', self.shipping_created)
self.event_store.unsubscribe('shipping', self.shipping_updated)
self.consumers.stop()
logging.info('stopped.')
def create_orders(self, _req):
orders = _req if isinstance(_req, list) else [_req]
order_ids = []
for order in orders:
try:
new_order = OrderService._create_entity(order['cart_id'])
except KeyError:
return {
"error": "missing mandatory parameter 'cart_id'"
}
# trigger event
self.event_store.publish('order', create_event('entity_created', new_order))
order_ids.append(new_order['entity_id'])
return {
"result": order_ids
}
def update_order(self, _req):
try:
order_id = _req['entity_id']
except KeyError:
return {
"error": "missing mandatory parameter 'entity_id'"
}
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': order_id})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
order = rsp['result']
if not order:
return {
"error": "could not find order"
}
# set new props
order['entity_id'] = order_id
try:
order['cart_id'] = _req['cart_id']
order['status'] = _req['status']
except KeyError:
return {
"result": "missing mandatory parameter 'cart_id' and/or 'status"
}
# trigger event
self.event_store.publish('order', create_event('entity_updated', order))
return {
"result": True
}
def delete_order(self, _req):
try:
order_id = _req['entity_id']
except KeyError:
return {
"error": "missing mandatory parameter 'entity_id'"
}
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': order_id})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
order = rsp['result']
if not order:
return {
"error": "could not find order"
}
# trigger event
self.event_store.publish('order', create_event('entity_deleted', order))
return {
"result": True
}
def billing_created(self, _item):
if _item.event_action != 'entity_created':
return
billing = json.loads(_item.event_data)
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': billing['order_id']})
order = rsp['result']
if not order['status'] == 'IN_STOCK':
return
order['status'] = 'CLEARED'
self.event_store.publish('order', create_event('entity_updated', order))
def billing_deleted(self, _item):
if _item.event_action != 'entity_delted':
return
billing = json.loads(_item.event_data)
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': billing['order_id']})
order = rsp['result']
if not order['status'] == 'CLEARED':
return
order['status'] = 'UNCLEARED'
self.event_store.publish('order', create_event('entity_updated', order))
def shipping_created(self, _item):
if _item.event_action != 'entity_created':
return
shipping = json.loads(_item.event_data)
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': shipping['order_id']})
order = rsp['result']
if not order['status'] == 'CLEARED':
return
order['status'] = 'SHIPPED'
self.event_store.publish('order', create_event('entity_updated', order))
def shipping_updated(self, _item):
if _item.event_action != 'entity_updated':
return
shipping = json.loads(_item.event_data)
if not shipping['delivered']:
return
rsp = send_message('read-model', 'get_entity', {'name': 'order', 'id': shipping['order_id']})
order = rsp['result']
order['status'] = 'DELIVERED'
self.event_store.publish('order', create_event('entity_updated', order))
class ShippingService(object):
"""
Shipping Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers('shipping-service', [
self.create_shippings, self.update_shipping, self.delete_shipping
])
@staticmethod
def _create_entity(_order_id, _delivered=0):
"""
Create a shipping entity.
:param _order_id: The order which is shipped.
:param _delivered: Optional TS indicating delivery, defaults to 0 (not delivered).
:return: A dict with the entity properties.
"""
return {
'entity_id': str(uuid.uuid4()),
'order_id': _order_id,
'delivered': _delivered
}
def start(self):
logging.info('starting ...')
self.event_store.subscribe('billing', self.billing_created)
self.consumers.start()
self.consumers.wait()
def stop(self):
self.event_store.unsubscribe('billing', self.billing_created)
self.consumers.stop()
logging.info('stopped.')
def create_shippings(self, _req):
shippings = _req if isinstance(_req, list) else [_req]
shipping_ids = []
for shipping in shippings:
try:
new_shipping = ShippingService._create_entity(
shipping['order_id'])
except KeyError:
return {
"error":
"missing mandatory parameter 'order_id' and/or 'delivered'"
}
# trigger event
self.event_store.publish(
'shipping', create_event('entity_created', new_shipping))
shipping_ids.append(new_shipping['entity_id'])
return {"result": shipping_ids}
def update_shipping(self, _req):
try:
shipping_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'shipping',
'id': shipping_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
shipping = rsp['result']
if not shipping:
return {"error": "could not find shipping"}
# set new props
shipping['entity_id'] = shipping_id
try:
shipping['order_id'] = _req['order_id']
shipping['delivered'] = _req['delivered']
except KeyError:
return {
"result":
"missing mandatory parameter 'order_id' and/or 'delivered"
}
# trigger event
self.event_store.publish('shipping',
create_event('entity_updated', shipping))
return {"result": True}
def delete_shipping(self, _req):
try:
shipping_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'shipping',
'id': shipping_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
shipping = rsp['result']
if not shipping:
return {"error": "could not find shipping"}
# trigger event
self.event_store.publish('shipping',
create_event('entity_deleted', shipping))
return {"result": True}
def billing_created(self, _item):
if _item.event_action != 'entity_created':
return
billing = json.loads(_item.event_data)
shipping = ShippingService._create_entity(billing['order_id'])
self.event_store.publish('shipping',
create_event('entity_created', shipping))
class InventoryService(object):
"""
Inventory Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers('inventory-service', [
self.create_inventories, self.update_inventory,
self.delete_inventory
])
@staticmethod
def _create_entity(_product_id, _amount):
"""
Create an inventory entity.
:param _product_id: The product ID the inventory is for.
:param _amount: The amount of products in the inventory.
:return: A dict with the entity properties.
"""
return {
'entity_id': str(uuid.uuid4()),
'product_id': _product_id,
'amount': _amount
}
def _incr_inventory(self, _product_id, _value=1):
rsp = send_message('read-model', 'get_entity', {
'name': 'inventory',
'props': {
'product_id': _product_id
}
})
if 'error' in rsp:
raise Exception(rsp['error'] + ' (from read-model)')
inventory = rsp['result']
if not inventory:
logging.error(
"could not find inventory for product {}".format(_product_id))
return False
inventory['amount'] = int(
inventory['amount']) - (_value if _value else 1)
# trigger event
self.event_store.publish('inventory',
create_event('entity_updated', inventory))
return True
def _decr_inventory(self, _product_id, _value=1):
rsp = send_message('read-model', 'get_entity', {
'name': 'inventory',
'props': {
'product_id': _product_id
}
})
if 'error' in rsp:
raise Exception(rsp['error'] + ' (from read-model)')
inventory = rsp['result']
if not inventory:
logging.warning(
"could not find inventory for product {}".format(_product_id))
return False
if int(inventory['amount']) - (_value if _value else 1) < 0:
logging.info("product {} is out of stock".format(_product_id))
return False
inventory['amount'] = int(
inventory['amount']) - (_value if _value else 1)
# trigger event
self.event_store.publish('inventory',
create_event('entity_updated', inventory))
return True
def _decr_from_cart(self, _cart):
try:
product_ids = _cart['product_ids']
except KeyError:
raise Exception("missing mandatory parameter 'product_ids'")
rsp = send_message('read-model', 'get_entities', {
'name': 'inventory',
'props': {
'product_id': product_ids
}
})
if 'error' in rsp:
raise Exception(rsp['error'] + ' (from read-model)')
inventories = rsp['result']
# count products
product_counts = []
for inventory in inventories:
found = product_ids.count(inventory['product_id'])
# check amount
if found > int(inventory['amount']):
logging.info("product {} is out of stock".format(
inventory['product_id']))
return False
product_counts.append((inventory, found))
# decrement inventory
for inventory, count in product_counts:
inventory['amount'] = int(inventory['amount']) - count
# trigger event
self.event_store.publish('inventory',
create_event('entity_updated', inventory))
return True
def start(self):
logging.info('starting ...')
self.event_store.subscribe('order', self.order_created)
self.event_store.subscribe('order', self.order_deleted)
self.consumers.start()
self.consumers.wait()
def stop(self):
self.event_store.unsubscribe('order', self.order_created)
self.event_store.unsubscribe('order', self.order_deleted)
self.consumers.stop()
logging.info('stopped.')
def create_inventories(self, _req):
inventory = _req if isinstance(_req, list) else [_req]
inventory_ids = []
for inventory in inventory:
try:
new_inventory = InventoryService._create_entity(
inventory['product_id'], inventory['amount'])
except KeyError:
return {
"error":
"missing mandatory parameter 'product_id' and/or 'amount'"
}
# trigger event
self.event_store.publish(
'inventory', create_event('entity_created', new_inventory))
inventory_ids.append(new_inventory['entity_id'])
return {"result": inventory_ids}
def update_inventory(self, _req):
try:
inventory_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'inventory',
'id': inventory_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
inventory = rsp['result']
if not inventory:
return {"error": "could not find inventory"}
# set new props
inventory['entity_id'] = inventory_id
try:
inventory['product_id'] = _req['product_id']
inventory['amount'] = _req['amount']
except KeyError:
return {
"result":
"missing mandatory parameter 'product_id' and/or 'amount"
}
# trigger event
self.event_store.publish('inventory',
create_event('entity_updated', inventory))
return {"result": True}
def delete_inventory(self, _req):
try:
inventory_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'inventory',
'id': inventory_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
inventory = rsp['result']
if not inventory:
return {"error": "could not find inventory"}
# trigger event
self.event_store.publish('inventory',
create_event('entity_deleted', inventory))
return {"result": True}
def order_created(self, _item):
if _item.event_action != 'entity_created':
return
order = json.loads(_item.event_data)
rsp = send_message('read-model', 'get_entity', {
'name': 'cart',
'id': order['cart_id']
})
cart = rsp['result']
result = self._decr_from_cart(cart)
order['status'] = 'IN_STOCK' if result else 'OUT_OF_STOCK'
self.event_store.publish('order', create_event('entity_updated',
order))
def order_deleted(self, _item):
if _item.event_action != 'entity_deleted':
return
order = json.loads(_item.event_data)
if order['status'] != 'IN_STOCK':
return
rsp = send_message('read-model', 'get_entity', {
'name': 'cart',
'id': order['cart_id']
})
cart = rsp['result']
[
self._incr_inventory(product_id)
for product_id in cart['product_ids']
]
class CartService(object):
"""
Cart Service class.
"""
def __init__(self):
self.event_store = EventStoreClient()
self.consumers = Consumers(
'cart-service',
[self.create_carts, self.update_cart, self.delete_cart])
@staticmethod
def _create_entity(_customer_id, _product_ids):
"""
Create a cart entity.
:param _customer_id: The customer ID.
:param _product_ids: The product IDs.
:return: A dict with the entity properties.
"""
return {
'entity_id': str(uuid.uuid4()),
'customer_id': _customer_id,
'product_ids': _product_ids
}
@staticmethod
def _check_inventory(_product_ids):
product_counts = collections.Counter(_product_ids)
for product_id, amount in product_counts.items():
rsp = send_message('read-model', 'get_entity', {
'name': 'inventory',
'props': {
'product_id': product_id
}
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
raise Exception(rsp['error'])
inventory = rsp['result']
if not inventory or int(inventory['amount']) - amount < 0:
return False, product_id
return True, None
def start(self):
logging.info('starting ...')
self.consumers.start()
self.consumers.wait()
def stop(self):
self.consumers.stop()
logging.info('stopped.')
def create_carts(self, _req):
carts = _req if isinstance(_req, list) else [_req]
cart_ids = []
for cart in carts:
res, product_id = self._check_inventory(cart['product_ids'])
if not res:
return {
'error': 'product {} is out of stock'.format(product_id)
}
try:
new_cart = CartService._create_entity(cart['customer_id'],
cart['product_ids'])
except KeyError:
return {
"error":
"missing mandatory parameter 'customer_id' and/or 'product_ids'"
}
# trigger event
self.event_store.publish('cart',
create_event('entity_created', new_cart))
cart_ids.append(new_cart['entity_id'])
return {"result": cart_ids}
def update_cart(self, _req):
try:
cart_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'order',
'props': {
'cart_id': cart_id
}
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
order = rsp['result']
if order and not order['status'] == 'CREATED':
return {"error": "order {} in progress".format(order['entity_id'])}
rsp = send_message('read-model', 'get_entity', {
'name': 'cart',
'id': cart_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
cart = rsp['result']
if not cart:
return {"error": "could not find cart {}".format(cart_id)}
# set new props
cart['entity_id'] = cart_id
try:
cart['customer_id'] = _req['customer_id']
cart['product_ids'] = _req['product_ids']
except KeyError:
return {
"result":
"missing mandatory parameter 'customer_id' and/or 'product_ids"
}
res, product_id = self._check_inventory(cart['product_ids'])
if not res:
return {'error': 'product {} is out of stock'.format(product_id)}
# trigger event
self.event_store.publish('cart', create_event('entity_updated', cart))
return {"result": True}
def delete_cart(self, _req):
try:
cart_id = _req['entity_id']
except KeyError:
return {"error": "missing mandatory parameter 'entity_id'"}
rsp = send_message('read-model', 'get_entity', {
'name': 'cart',
'id': cart_id
})
if 'error' in rsp:
rsp['error'] += ' (from read-model)'
return rsp
cart = rsp['result']
if not cart:
return {"error": "could not find cart"}
# trigger event
self.event_store.publish('cart', create_event('entity_deleted', cart))
return {"result": True}