An embed request simply contains a transform option called metadata that contains a map of property names to values, resulting in transform options like the following:
{"metadata":
{"{http://www.alfresco.org/model/content/1.0}author":"Fred",
"{http://www.alfresco.org/model/content/1.0}title":"Making Bread"
"{http://www.alfresco.org/model/content/1.0}helpers":["Jane","Paul"]},
"timeout":20000,
"sourceEncoding":"UTF-8"}
Values are either a String, or a Collection of Strings. The mappings of these content repository properties to metadata properties is normally the reverse of those defined in the <classname>_metadata_extract.properties file in the T-Engine.
Metadata embed response:
This is simply the source content with the metadata embedded. The content repository updates the content of the node with what is returned.