So far in this chapter, we have used requests with binary bodies. This is suitable for microservices, but if you want to send files with an HTML form, you should use a request with a multipart/form-data type of content. This allows a client to include multiple files in a single request, but it also needs a parser to split files from the body of a request. The hyper crate doesn't include a parser for multipart requests, and you can use other crates such as the multipart crate to parse requests instead. This, however, doesn't work asynchronously, so you should use the multipart-async crate with the latest versions of the hyper crate. You can also implement multipart requests yourself. To implement this, you can create a struct that implements the Stream trait and parses incoming chunks of data. Multipart requests have the multipart/form-data content type with a boundary value such as boundary=53164434ae464234f. Its body contains a separator and the embedded files:

--------------------------53164434ae464234f
Content-Disposition: form-data; name="first_file"; filename="file1.txt"
Content-Type: text/plain
Contents of the file1.txt
--------------------------53164434ae464234f
Content-Disposition: form-data; name="second_file"; filename="file2.txt"
Content-Type: text/plain
Contents of the file2.txt
--------------------------53164434ae464234f

Your stream has to implement Stream<Item=FileEntry>, which reads a request and extracts files using the provided boundary.