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| 1 | +# Copyright 2018-Present The CloudEvents Authors |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 4 | +# not use this file except in compliance with the License. You may obtain |
| 5 | +# a copy of the License at |
| 6 | +# |
| 7 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 11 | +# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 12 | +# License for the specific language governing permissions and limitations |
| 13 | +# under the License. |
| 14 | +import base64 |
| 15 | +import json |
| 16 | +import typing |
| 17 | + |
| 18 | +from cloudevents import exceptions as cloud_exceptions |
| 19 | +from cloudevents import http |
| 20 | +from cloudevents.abstract import AnyCloudEvent |
| 21 | +from cloudevents.kafka.exceptions import KeyMapperError |
| 22 | +from cloudevents.sdk import types |
| 23 | + |
| 24 | +DEFAULT_MARSHALLER: types.MarshallerType = json.dumps |
| 25 | +DEFAULT_UNMARSHALLER: types.MarshallerType = json.loads |
| 26 | +DEFAULT_EMBEDDED_DATA_MARSHALLER: types.MarshallerType = lambda x: x |
| 27 | + |
| 28 | + |
| 29 | +class KafkaMessage(typing.NamedTuple): |
| 30 | + """ |
| 31 | + Represents the elements of a message sent or received through the Kafka protocol. |
| 32 | + Callers can map their client-specific message representation to and from this |
| 33 | + type in order to use the cloudevents.kafka conversion functions. |
| 34 | + """ |
| 35 | + |
| 36 | + headers: typing.Dict[str, bytes] |
| 37 | + """ |
| 38 | + The dictionary of message headers key/values. |
| 39 | + """ |
| 40 | + |
| 41 | + key: typing.Optional[typing.Union[bytes, str]] |
| 42 | + """ |
| 43 | + The message key. |
| 44 | + """ |
| 45 | + |
| 46 | + value: typing.Union[bytes, str] |
| 47 | + """ |
| 48 | + The message value. |
| 49 | + """ |
| 50 | + |
| 51 | + |
| 52 | +KeyMapper = typing.Callable[[AnyCloudEvent], typing.Union[bytes, str]] |
| 53 | +""" |
| 54 | +A callable function that creates a Kafka message key, given a CloudEvent instance. |
| 55 | +""" |
| 56 | + |
| 57 | +DEFAULT_KEY_MAPPER: KeyMapper = lambda event: event.get("partitionkey") |
| 58 | +""" |
| 59 | +The default KeyMapper which maps the user provided `partitionkey` attribute value |
| 60 | + to the `key` of the Kafka message as-is, if present. |
| 61 | +""" |
| 62 | + |
| 63 | + |
| 64 | +def to_binary( |
| 65 | + event: AnyCloudEvent, |
| 66 | + data_marshaller: typing.Optional[types.MarshallerType] = None, |
| 67 | + key_mapper: typing.Optional[KeyMapper] = None, |
| 68 | +) -> KafkaMessage: |
| 69 | + """ |
| 70 | + Returns a KafkaMessage in binary format representing this Cloud Event. |
| 71 | +
|
| 72 | + :param event: The event to be converted. To specify the Kafka messaage Key, set |
| 73 | + the `partitionkey` attribute of the event, or provide a KeyMapper. |
| 74 | + :param data_marshaller: Callable function to cast event.data into |
| 75 | + either a string or bytes. |
| 76 | + :param key_mapper: Callable function to get the Kafka message key. |
| 77 | + :returns: KafkaMessage |
| 78 | + """ |
| 79 | + data_marshaller = data_marshaller or DEFAULT_MARSHALLER |
| 80 | + key_mapper = key_mapper or DEFAULT_KEY_MAPPER |
| 81 | + |
| 82 | + try: |
| 83 | + message_key = key_mapper(event) |
| 84 | + except Exception as e: |
| 85 | + raise KeyMapperError( |
| 86 | + f"Failed to map message key with error: {type(e).__name__}('{e}')" |
| 87 | + ) |
| 88 | + |
| 89 | + headers = {} |
| 90 | + if event["content-type"]: |
| 91 | + headers["content-type"] = event["content-type"].encode("utf-8") |
| 92 | + for attr, value in event.get_attributes().items(): |
| 93 | + if attr not in ["data", "partitionkey", "content-type"]: |
| 94 | + if value is not None: |
| 95 | + headers["ce_{0}".format(attr)] = value.encode("utf-8") |
| 96 | + |
| 97 | + try: |
| 98 | + data = data_marshaller(event.data) |
| 99 | + except Exception as e: |
| 100 | + raise cloud_exceptions.DataMarshallerError( |
| 101 | + f"Failed to marshall data with error: {type(e).__name__}('{e}')" |
| 102 | + ) |
| 103 | + if isinstance(data, str): |
| 104 | + data = data.encode("utf-8") |
| 105 | + |
| 106 | + return KafkaMessage(headers, message_key, data) |
| 107 | + |
| 108 | + |
| 109 | +def from_binary( |
| 110 | + message: KafkaMessage, |
| 111 | + event_type: typing.Optional[typing.Type[AnyCloudEvent]] = None, |
| 112 | + data_unmarshaller: typing.Optional[types.MarshallerType] = None, |
| 113 | +) -> AnyCloudEvent: |
| 114 | + """ |
| 115 | + Returns a CloudEvent from a KafkaMessage in binary format. |
| 116 | +
|
| 117 | + :param message: The KafkaMessage to be converted. |
| 118 | + :param event_type: The type of CloudEvent to create. Defaults to http.CloudEvent. |
| 119 | + :param data_unmarshaller: Callable function to map data to a python object |
| 120 | + :returns: CloudEvent |
| 121 | + """ |
| 122 | + |
| 123 | + data_unmarshaller = data_unmarshaller or DEFAULT_UNMARSHALLER |
| 124 | + event_type = event_type or http.CloudEvent |
| 125 | + |
| 126 | + attributes = {} |
| 127 | + |
| 128 | + for header, value in message.headers.items(): |
| 129 | + header = header.lower() |
| 130 | + if header == "content-type": |
| 131 | + attributes["content-type"] = value.decode() |
| 132 | + elif header.startswith("ce_"): |
| 133 | + attributes[header[3:]] = value.decode() |
| 134 | + |
| 135 | + if message.key is not None: |
| 136 | + attributes["partitionkey"] = message.key |
| 137 | + |
| 138 | + try: |
| 139 | + data = data_unmarshaller(message.value) |
| 140 | + except Exception as e: |
| 141 | + raise cloud_exceptions.DataUnmarshallerError( |
| 142 | + f"Failed to unmarshall data with error: {type(e).__name__}('{e}')" |
| 143 | + ) |
| 144 | + |
| 145 | + return event_type.create(attributes, data) |
| 146 | + |
| 147 | + |
| 148 | +def to_structured( |
| 149 | + event: AnyCloudEvent, |
| 150 | + data_marshaller: typing.Optional[types.MarshallerType] = None, |
| 151 | + envelope_marshaller: typing.Optional[types.MarshallerType] = None, |
| 152 | + key_mapper: typing.Optional[KeyMapper] = None, |
| 153 | +) -> KafkaMessage: |
| 154 | + """ |
| 155 | + Returns a KafkaMessage in structured format representing this Cloud Event. |
| 156 | +
|
| 157 | + :param event: The event to be converted. To specify the Kafka message KEY, set |
| 158 | + the `partitionkey` attribute of the event. |
| 159 | + :param data_marshaller: Callable function to cast event.data into |
| 160 | + either a string or bytes. |
| 161 | + :param envelope_marshaller: Callable function to cast event envelope into |
| 162 | + either a string or bytes. |
| 163 | + :param key_mapper: Callable function to get the Kafka message key. |
| 164 | + :returns: KafkaMessage |
| 165 | + """ |
| 166 | + data_marshaller = data_marshaller or DEFAULT_EMBEDDED_DATA_MARSHALLER |
| 167 | + envelope_marshaller = envelope_marshaller or DEFAULT_MARSHALLER |
| 168 | + key_mapper = key_mapper or DEFAULT_KEY_MAPPER |
| 169 | + |
| 170 | + try: |
| 171 | + message_key = key_mapper(event) |
| 172 | + except Exception as e: |
| 173 | + raise KeyMapperError( |
| 174 | + f"Failed to map message key with error: {type(e).__name__}('{e}')" |
| 175 | + ) |
| 176 | + |
| 177 | + attrs = event.get_attributes().copy() |
| 178 | + |
| 179 | + try: |
| 180 | + data = data_marshaller(event.data) |
| 181 | + except Exception as e: |
| 182 | + raise cloud_exceptions.DataMarshallerError( |
| 183 | + f"Failed to marshall data with error: {type(e).__name__}('{e}')" |
| 184 | + ) |
| 185 | + if isinstance(data, (bytes, bytes, memoryview)): |
| 186 | + attrs["data_base64"] = base64.b64encode(data).decode("ascii") |
| 187 | + else: |
| 188 | + attrs["data"] = data |
| 189 | + |
| 190 | + headers = {} |
| 191 | + if "content-type" in attrs: |
| 192 | + headers["content-type"] = attrs.pop("content-type").encode("utf-8") |
| 193 | + |
| 194 | + try: |
| 195 | + value = envelope_marshaller(attrs) |
| 196 | + except Exception as e: |
| 197 | + raise cloud_exceptions.DataMarshallerError( |
| 198 | + f"Failed to marshall event with error: {type(e).__name__}('{e}')" |
| 199 | + ) |
| 200 | + |
| 201 | + if isinstance(value, str): |
| 202 | + value = value.encode("utf-8") |
| 203 | + |
| 204 | + return KafkaMessage(headers, message_key, value) |
| 205 | + |
| 206 | + |
| 207 | +def from_structured( |
| 208 | + message: KafkaMessage, |
| 209 | + event_type: typing.Optional[typing.Type[AnyCloudEvent]] = None, |
| 210 | + data_unmarshaller: typing.Optional[types.MarshallerType] = None, |
| 211 | + envelope_unmarshaller: typing.Optional[types.MarshallerType] = None, |
| 212 | +) -> AnyCloudEvent: |
| 213 | + """ |
| 214 | + Returns a CloudEvent from a KafkaMessage in structured format. |
| 215 | +
|
| 216 | + :param message: The KafkaMessage to be converted. |
| 217 | + :param event_type: The type of CloudEvent to create. Defaults to http.CloudEvent. |
| 218 | + :param data_unmarshaller: Callable function to map the data to a python object. |
| 219 | + :param envelope_unmarshaller: Callable function to map the envelope to a python |
| 220 | + object. |
| 221 | + :returns: CloudEvent |
| 222 | + """ |
| 223 | + |
| 224 | + data_unmarshaller = data_unmarshaller or DEFAULT_EMBEDDED_DATA_MARSHALLER |
| 225 | + envelope_unmarshaller = envelope_unmarshaller or DEFAULT_UNMARSHALLER |
| 226 | + event_type = event_type or http.CloudEvent |
| 227 | + |
| 228 | + try: |
| 229 | + structure = envelope_unmarshaller(message.value) |
| 230 | + except Exception as e: |
| 231 | + raise cloud_exceptions.DataUnmarshallerError( |
| 232 | + "Failed to unmarshall message with error: " f"{type(e).__name__}('{e}')" |
| 233 | + ) |
| 234 | + |
| 235 | + attributes = {} |
| 236 | + if message.key is not None: |
| 237 | + attributes["partitionkey"] = message.key |
| 238 | + |
| 239 | + for name, value in structure.items(): |
| 240 | + decoder = lambda x: x |
| 241 | + if name == "data": |
| 242 | + decoder = lambda v: data_unmarshaller(v) |
| 243 | + if name == "data_base64": |
| 244 | + decoder = lambda v: data_unmarshaller(base64.b64decode(v)) |
| 245 | + name = "data" |
| 246 | + |
| 247 | + try: |
| 248 | + decoded_value = decoder(value) |
| 249 | + except Exception as e: |
| 250 | + raise cloud_exceptions.DataUnmarshallerError( |
| 251 | + "Failed to unmarshall data with error: " f"{type(e).__name__}('{e}')" |
| 252 | + ) |
| 253 | + if name == "data": |
| 254 | + data = decoded_value |
| 255 | + else: |
| 256 | + attributes[name] = decoded_value |
| 257 | + |
| 258 | + for header, val in message.headers.items(): |
| 259 | + attributes[header.lower()] = val.decode() |
| 260 | + |
| 261 | + return event_type.create(attributes, data) |
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