mirror of
https://github.com/enso-org/enso.git
synced 2024-12-23 21:12:44 +03:00
87 lines
3.5 KiB
Markdown
87 lines
3.5 KiB
Markdown
---
|
|
layout: developer-doc
|
|
title: Streaming File Transfer
|
|
category: language-server
|
|
tags: [language-server, protocol, specification]
|
|
order: 5
|
|
---
|
|
|
|
# Streaming File Transfer
|
|
|
|
Particularly important in the separate-server design that we provide with the
|
|
Language Server is the ability to transfer files to and from the remote machine.
|
|
To that end, it is important that we provide the ability for the IDE to both
|
|
upload and download very large files.
|
|
|
|
A few key requirements:
|
|
|
|
- We want to support resumption of transfers.
|
|
- We want to have transfers be as low-overhead as possible.
|
|
- Multiple transfers may be occurring at once.
|
|
- We want to keep implementation simple to avoid errors (ideally no state).
|
|
|
|
<!-- MarkdownTOC levels="2,3" autolink="true" indent=" " -->
|
|
|
|
- [Control](#control)
|
|
- [Concurrency](#concurrency)
|
|
- [UX](#ux)
|
|
|
|
<!-- /MarkdownTOC -->
|
|
|
|
## Control
|
|
|
|
In order to make this portion of the protocol simple to manage, it is defined in
|
|
a stateless fashion. The Language Server provides two messages `file/writeBytes`
|
|
and `file/readByteRange` with corresponding responses. We make the following
|
|
assumptions:
|
|
|
|
- Each request must be completed with a response before sending another request
|
|
for the same file.
|
|
- Basic file information can be provided by the existing `file/info` API, which
|
|
allows the IDE to create progress spinners and other such niceties.
|
|
- All requests and responses are contained within the `InboundMessage` and
|
|
`OutboundMessage` containers respectively.
|
|
|
|
The assumption is that, rather than encoding a stateful protocol, we instead
|
|
rely on the IDE to control the upload and download of files by sending
|
|
successive requests. To upload files, we intend for the IDE to use
|
|
`file/writeBytes`, and to download files we intend for `file/readBytes` to be
|
|
used.
|
|
|
|
Resumption of transfers is also handled by the IDE, which may keep track of what
|
|
portions of a file have been written or read.
|
|
|
|
### Concurrency
|
|
|
|
The language server natively supports running these file operations in parallel
|
|
as it spawns a separate request-handler actor for each operation. It does,
|
|
however, not provide any _intrinsic_ guarantees to its operation. As _all_ file
|
|
operations are evaluated in parallel, coordinating them for consistency is up to
|
|
the IDE.
|
|
|
|
For example, if you want to write bytes to a file `f1` and then checksum the
|
|
resulting file, you need to wait for the `WriteBytesReply` to come back before
|
|
sending `file/checksum(f1)`. Otherwise, there is no guarantee that the write has
|
|
completed by the time the checksum is calculated.
|
|
|
|
## UX
|
|
|
|
The IDE wants to be able to provide two major UX benefits to users as part of
|
|
this work:
|
|
|
|
1. Loading spinners that show the progress of the file.
|
|
2. A display of parts of the graph that are waiting on the file.
|
|
|
|
The first requirement here is trivially handled due to the IDE-driven nature of
|
|
the file upload and download process. As they know the size of the file being
|
|
transferred and get acknowledgements of each chunk of the file that is sent,
|
|
they know both the speed and the amount of the file that has been uploaded.
|
|
|
|
The second requirement is being handled by the addition of the
|
|
`Visualization.file_uploading` method to the `Visualization` portion of the
|
|
standard library. This is a method that returns a dataflow error
|
|
`File_Being_Uploaded path` that will flow through the graph to annotate all
|
|
portions waiting on the file upload. All the IDE has to do is insert this
|
|
expression implicitly into the source file while the upload is progressing, and
|
|
it can trace the impacted nodes and display the necessary UI details.
|