HttpEndpoint(mapping=None, *, ignore_unknown_fields=False, **kwargs)Represents a HTTP endpoint destination.
Attributes |
|
|---|---|
| Name | Description |
uri |
str
Required. The URI of the HTTP endpoint. The value must be a RFC2396 URI string. Examples: https://svc.us-central1.p.local:8080/route. Only the
HTTPS protocol is supported.
|
message_binding_template |
str
Optional. The CEL expression used to modify how the destination-bound HTTP request is constructed. If a binding expression is not specified here, the message is treated as a CloudEvent and is mapped to the HTTP request according to the CloudEvent HTTP Protocol Binding Binary Content Mode (https://github.com/cloudevents/spec/blob/main/cloudevents/bindings/http-protocol-binding.md#31-binary-content-mode). In this representation, all fields except the data and
datacontenttype field on the message are mapped to HTTP
request headers with a prefix of ce-.
To construct the HTTP request payload and the value of the
content-type HTTP header, the payload format is defined as
follows:
1) Use the output_payload_format_type on the
Pipeline.Destination if it is set, else:
2) Use the input_payload_format_type on the Pipeline if it
is set, else:
3) Treat the payload as opaque binary data.
The data field of the message is converted to the
payload format or left as-is for case 3) and then attached
as the payload of the HTTP request. The content-type
header on the HTTP request is set to the payload format type
or left empty for case 3). However, if a mediation has
updated the datacontenttype field on the message so that
it is not the same as the payload format type but it is
still a prefix of the payload format type, then the
content-type header on the HTTP request is set to this
datacontenttype value. For example, if the
datacontenttype is "application/json" and the payload
format type is "application/json; charset=utf-8", then the
content-type header on the HTTP request is set to
"application/json; charset=utf-8".
If a non-empty binding expression is specified then this
expression is used to modify the default CloudEvent HTTP
Protocol Binding Binary Content representation. The result
of the CEL expression must be a map of key/value pairs which
is used as follows:
- If a map named headers exists on the result of the
expression, then its key/value pairs are directly mapped
to the HTTP request headers. The headers values are
constructed from the corresponding value type's canonical
representation. If the headers field doesn't exist
then the resulting HTTP request will be the headers of the
CloudEvent HTTP Binding Binary Content Mode representation
of the final message. Note: If the specified binding
expression, has updated the datacontenttype field on
the message so that it is not the same as the payload
format type but it is still a prefix of the payload format
type, then the content-type header in the headers
map is set to this datacontenttype value.
- If a field named body exists on the result of the
expression then its value is directly mapped to the body
of the request. If the value of the body field is of
type bytes or string then it is used for the HTTP request
body as-is, with no conversion. If the body field is of
any other type then it is converted to a JSON string. If
the body field does not exist then the resulting payload
of the HTTP request will be data value of the CloudEvent
HTTP Binding Binary Content Mode representation of the
final message as described earlier.
- Any other fields in the resulting expression will be
ignored.
The CEL expression may access the incoming CloudEvent
message in its definition, as follows:
- The data field of the incoming CloudEvent message can
be accessed using the message.data value. Subfields of
message.data may also be accessed if an
input_payload_format has been specified on the Pipeline.
- Each attribute of the incoming CloudEvent message can be
accessed using the message. value, where is
replaced with the name of the attribute.
- Existing headers can be accessed in the CEL expression
using the headers variable. The headers variable
defines a map of key/value pairs corresponding to the HTTP
headers of the CloudEvent HTTP Binding Binary Content Mode
representation of the final message as described earlier.
For example, the following CEL expression can be used to
construct an HTTP request by adding an additional header
to the HTTP headers of the CloudEvent HTTP Binding Binary
Content Mode representation of the final message and by
overwriting the body of the request:
::
{
"headers": headers.merge({"new-header-key": "new-header-value"}),
"body": "new-body"
}
- The default binding for the message payload can be
accessed using the body variable. It conatins a string
representation of the message payload in the format
specified by the output_payload_format field. If the
input_payload_format field is not set, the body
variable contains the same message payload bytes that were
published.
Additionally, the following CEL extension functions are
provided for use in this CEL expression:
- toBase64Url: map.toBase64Url() -> string
- Converts a CelValue to a base64url encoded string
- toJsonString: map.toJsonString() -> string
- Converts a CelValue to a JSON string
- merge: map1.merge(map2) -> map3
- Merges the passed CEL map with the existing CEL map the
function is applied to.
- If the same key exists in both maps, if the key's value
is type map both maps are merged else the value from the
passed map is used.
- denormalize: map.denormalize() -> map
- Denormalizes a CEL map such that every value of type map
or key in the map is expanded to return a single level
map.
- The resulting keys are "." separated indices of the map
keys.
- For example: { "a": 1, "b": { "c": 2, "d": 3 } "e": [4,
5] } .denormalize() -> { "a": 1, "b.c": 2, "b.d": 3,
"e.0": 4, "e.1": 5 }
- setField: map.setField(key, value) -> message
- Sets the field of the message with the given key to the
given value.
- If the field is not present it will be added.
- If the field is present it will be overwritten.
- The key can be a dot separated path to set a field in a
nested message.
- Key must be of type string.
- Value may be any valid type.
- removeFields: map.removeFields([key1, key2, ...]) ->
message
- Removes the fields of the map with the given keys.
- The keys can be a dot separated path to remove a field
in a nested message.
- If a key is not found it will be ignored.
- Keys must be of type string.
- toMap: [map1, map2, ...].toMap() -> map
- Converts a CEL list of CEL maps to a single CEL map
- toCloudEventJsonWithPayloadFormat:
message.toCloudEventJsonWithPayloadFormat() -> map
- Converts a message to the corresponding structure of
JSON format for CloudEvents.
- It converts data to destination payload format
specified in output_payload_format. If
output_payload_format is not set, the data will
remain unchanged.
- It also sets the corresponding datacontenttype of the
CloudEvent, as indicated by output_payload_format.
If no output_payload_format is set it will use the
value of the "datacontenttype" attribute on the
CloudEvent if present, else remove "datacontenttype"
attribute.
- This function expects that the content of the message
will adhere to the standard CloudEvent format. If it
doesn't then this function will fail.
- The result is a CEL map that corresponds to the JSON
representation of the CloudEvent. To convert that data
to a JSON string it can be chained with the toJsonString
function.
The Pipeline expects that the message it receives adheres to
the standard CloudEvent format. If it doesn't then the
outgoing message request may fail with a persistent error.
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