MarloweTransfer sub-protocol

The MarloweTransfer sub-protocol is defined here:

• https://github.com/input-output-hk/marlowe-cardano/blob/main/marlowe-runtime/contract-api/Language/Marlowe/Protocol/Transfer/Types.hs

Below is a state diagram for the MarloweLoad sub-protocol:

The MarloweTransfer sub-protocol is used to efficiently transfer contracts to and from the contract store. It uses the object bundle format and works in import or export mode.

Sub-protocol states

Protocol state	Agency	Description
1. Idle	Client	The server is waiting for the client to start an upload or a download.
2. Export	Server	The server is determining if the requested contract can be exported.
3. CanDownload	Client	The client can download the next partial object bundle from the server.
4. Download	Server	The server is retrieving the next partial object bundle for the client.
5. CanUpload	Client	The client can upload the next partial object bundle to the server.
6. Upload	Server	The server is processing a partial object bundle from the client.
7. Done	Nobody	The protocol session is done.

Messages

Message	Begin state	End state	Parameter	Description
1. StartImport	Idle	CanUpload		The client starts an import session.
2. RequestExport hash	Idle	Export		The client requests an export of the contract identified by its hash.
			hash	The hash of the contract to export.
3. StartExport	Export	CanDownload		The server has verified the export request and cleared the client to begin downloading.
4. ContractNotFound	Export	Idle		The server was unable to find the given contract and is refusing the export request.
5. Done	Idle	Done		The client ends the session.
6. Upload bundlePart	CanUpload	Upload		The client uploads the next part of the bundle to the server.
			bundlePart	The next part of the object bundle that comes after the previous one.
7. Uploaded mapping	Upload	CanUpload		The server has processed the uploaded bundle part and is ready for the next one.
			mapping	A mapping of contract labels in the bundle to their hashes (post-merkleization).
8. UploadFailed err	Upload	Idle		The client tried to upload an invalid bundle part.
			err	What went wrong while processing the bundle part.
9. Imported	CanUpload	Idle		The client has no more bundle parts left to push.
10. Download n	CanDownload	Download		The client requests the next n objects in the bundle.
			n	The maximum number of objects the client wants to receive.
11. Downloaded bundlePart	Download	CanDownload		The server sends the next bundle part to the client.
			bundlePart	The next part of the object bundle that comes after the previous one.
12. Exported	Download	Idle		The server has no more bundle parts to send.
13. Cancel	CanDownload	Idle		The client is cancelling the download.