How to post a multipart/form-data File Upload using image URL in WSO2

Need help with the following requirement. 1> get a file from an URL 2> post the file as a multipart/form-data request to a file upload api

For example: the below image url which responds with the google logo

"https://images.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"

to be posted as multipart/form-data request to a file upload api i.e: curl --location 'http://localhost:8290/upload/form'
--form 'companyId="100"'
--form 'companyName="google"'
--form 'website="google.com"'
--form 'file=@"/path/to/file"'

The following script gets the image from an url

<api context="/processFile" name="processFile" xmlns="http://ws.apache.org/ns/synapse">
    <resource methods="POST">
        <inSequence>
            <property expression="$body//url" name="uri.var.fileUrl" scope="default" type="STRING"/>
            <call>
                <endpoint>
                    <http method="get" uri-template="{uri.var.fileUrl}">
                        <suspendOnFailure>
                            <initialDuration>-1</initialDuration>
                            <progressionFactor>-1</progressionFactor>
                            <maximumDuration>0</maximumDuration>
                        </suspendOnFailure>
                        <markForSuspension>
                            <retriesBeforeSuspension>0</retriesBeforeSuspension>
                        </markForSuspension>
                    </http>
                </endpoint>
            </call>
            <respond/>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </resource>
</api>

However need help to submit the image file as a multipart/form-data request to a file upload api(as in the attached screenshot) in the same process flow.

Here is an example, you may have to adjust the API based on the exact requirement.

First add the following to the deployment.toml to support retrieving the file.

[[custom_message_builders]]
class = "org.wso2.carbon.relay.BinaryRelayBuilder"
content_type = "image/png"

Then refer the following API to create the Multipart request with the binary payload.

<?xml version="1.0" encoding="UTF-8"?>
<api context="/multi" name="MultiPartSample" xmlns="http://ws.apache.org/ns/synapse">
    <resource methods="GET">
        <inSequence>
            <log>
                <property name="MSG" value="In API"/>
            </log>
            <call>
                <endpoint>
                    <http method="get" uri-template="https://images.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png">
                        <suspendOnFailure>
                            <initialDuration>-1</initialDuration>
                            <progressionFactor>-1</progressionFactor>
                            <maximumDuration>0</maximumDuration>
                        </suspendOnFailure>
                        <markForSuspension>
                            <retriesBeforeSuspension>0</retriesBeforeSuspension>
                        </markForSuspension>
                    </http>
                </endpoint>
            </call>
            <payloadFactory media-type="xml">
                <format>
                    <root xmlns="">
                        <companyId>100</companyId>
                        <companyName>google</companyName>
                        <file filename="something.png" content-type="image/png" >$1</file>
                    </root>
                </format>
                <args>
                    <arg evaluator="xml" expression="$body/ns:binary" xmlns:ns="http://ws.apache.org/commons/ns/payload"/>
                </args>
            </payloadFactory>
            <property name="messageType" scope="axis2" type="STRING" value="multipart/form-data"/>
            <call>
                <endpoint>
                    <http method="post" uri-template="https://your_seconf_file_upload_api">
                        <suspendOnFailure>
                            <initialDuration>-1</initialDuration>
                            <progressionFactor>-1</progressionFactor>
                            <maximumDuration>0</maximumDuration>
                        </suspendOnFailure>
                        <markForSuspension>
                            <retriesBeforeSuspension>0</retriesBeforeSuspension>
                        </markForSuspension>
                    </http>
                </endpoint>
            </call>
        </inSequence>
        <outSequence/>
        <faultSequence/>
    </resource>
</api>

The outcome