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.<key> value, where <key> 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:
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.
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.
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.<key> value, where <key> 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:
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.
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.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-10-02 UTC."],[],[]]
