syncular_client/transport.rs
1//! The transport seam handed TO the client by its host (the conformance
2//! harness, an app shell, …). Bytes and strings only — mirroring the
3//! `ClientEndpoints` inversion of the conformance driver contract. The
4//! client is synchronous: the driver protocol is request/response.
5
6/// A transport-level or request-level failure (§1.1 HTTP-JSON surface).
7#[derive(Debug, Clone)]
8pub struct TransportError {
9 pub code: String,
10 pub message: String,
11}
12
13impl TransportError {
14 pub fn new(code: impl Into<String>, message: impl Into<String>) -> Self {
15 TransportError {
16 code: code.into(),
17 message: message.into(),
18 }
19 }
20}
21
22/// Direct-endpoint segment fetch (§5.5). Signed-URL descriptors never
23/// reach this call: the §5.4 resolution lives in the client core, which
24/// routes url-carrying descriptors through `fetch_url` instead.
25#[derive(Debug, Clone)]
26pub struct SegmentRequest {
27 pub segment_id: String,
28 pub table: String,
29 /// Canonical JSON (§11.2) of the requested scope map (§5.5).
30 pub requested_scopes_json: String,
31}
32
33/// A §5.9.5 blob download result: inline bytes, or a presigned url the client
34/// fetches directly (always-issue). `url_expires_at_ms` is present iff `url`.
35#[derive(Debug, Clone)]
36pub enum BlobDownload {
37 Bytes(Vec<u8>),
38 Url {
39 url: String,
40 url_expires_at_ms: Option<i64>,
41 },
42}
43
44/// A §5.9.3 presigned-upload grant: a single PUT url, an already-present
45/// marker (skip the PUT), or none (stream through the direct endpoint).
46#[derive(Debug, Clone)]
47pub enum BlobUploadGrant {
48 Url {
49 url: String,
50 url_expires_at_ms: Option<i64>,
51 },
52 Present,
53 None,
54}
55
56pub trait Transport {
57 /// One combined push+pull round trip (§1.5) over the request/response
58 /// binding (`POST /sync`, loopback, …).
59 fn sync(&mut self, request: &[u8]) -> Result<Vec<u8>, TransportError>;
60 /// One combined push+pull round over the realtime socket (§8.7). The
61 /// host owns the WS-binding mechanics — channel tags, chunk assembly
62 /// to the response's END — and returns the assembled response bytes.
63 /// The client calls this instead of `sync` whenever realtime is
64 /// connected (Direction decision 1: the socket IS the sync-round
65 /// transport, not a fallback pair); the server registers the round's
66 /// subscriptions on the connection at round end, so no reconnect is
67 /// needed after subscription changes.
68 fn realtime_sync(&mut self, request: &[u8]) -> Result<Vec<u8>, TransportError>;
69 /// Segment download via the direct endpoint (§5.5).
70 fn download_segment(&mut self, request: &SegmentRequest) -> Result<Vec<u8>, TransportError>;
71 /// §5.4 direct URL fetch capability: `true` makes the client
72 /// advertise accept bit 3 (capability negotiation, §4.2). Default:
73 /// not capable.
74 fn supports_url_fetch(&self) -> bool {
75 false
76 }
77 /// Plain GET of a signed URL (§5.4). The URL is the entire grant —
78 /// implementations MUST NOT attach sync-server authentication or the
79 /// `X-Syncular-Scopes` header. Only called when `supports_url_fetch`
80 /// returned `true`.
81 fn fetch_url(&mut self, url: &str) -> Result<Vec<u8>, TransportError> {
82 let _ = url;
83 Err(TransportError::new(
84 "sync.invalid_request",
85 "this transport has no direct URL fetch (§5.4)",
86 ))
87 }
88 /// §5.9.3 blob upload: host-authenticated `PUT <mount>/blobs/{blobId}`.
89 /// The server verifies the content address. Default: unsupported.
90 fn blob_upload(
91 &mut self,
92 blob_id: &str,
93 bytes: &[u8],
94 media_type: Option<&str>,
95 ) -> Result<(), TransportError> {
96 let _ = (blob_id, bytes, media_type);
97 Err(TransportError::new(
98 "sync.invalid_request",
99 "this transport has no blob upload (§5.9)",
100 ))
101 }
102 /// §5.9.5 blob download: host-authenticated `GET <mount>/blobs/{blobId}`,
103 /// re-authorized server-side against referencing rows. Returns inline
104 /// bytes OR (always-issue, presign configured) a signed url the client
105 /// fetches directly. Default: none.
106 fn blob_download(&mut self, blob_id: &str) -> Result<BlobDownload, TransportError> {
107 let _ = blob_id;
108 Err(TransportError::new(
109 "blob.not_found",
110 "this transport has no blob download (§5.9)",
111 ))
112 }
113 /// §5.9.5 presigned-download fetch: a bare GET of the signed url. MUST
114 /// attach NO host authentication — the url is the entire grant (§5.4).
115 /// Only called when `blob_download` returned a `Url` arm.
116 fn fetch_blob_url(&mut self, url: &str) -> Result<Vec<u8>, TransportError> {
117 let _ = url;
118 Err(TransportError::new(
119 "sync.invalid_request",
120 "this transport has no blob url fetch (§5.9.5)",
121 ))
122 }
123 /// §5.9.3 presigned-upload grant: `POST /blobs/{blobId}/upload-grant` with
124 /// the declared size. Absent (`None`) ⇒ the client always streams through
125 /// `blob_upload`. A `Url` grant is PUT via `blob_put_url`.
126 fn blob_upload_grant(
127 &mut self,
128 blob_id: &str,
129 byte_length: u64,
130 media_type: Option<&str>,
131 ) -> Result<BlobUploadGrant, TransportError> {
132 let _ = (blob_id, byte_length, media_type);
133 Ok(BlobUploadGrant::None)
134 }
135 /// §5.9.3 direct-to-storage PUT of the granted url. MUST attach NO host
136 /// authentication — the presigned url is the entire grant (§5.4). Only
137 /// called when `blob_upload_grant` returned a `Url` arm.
138 fn blob_put_url(
139 &mut self,
140 url: &str,
141 bytes: &[u8],
142 media_type: Option<&str>,
143 ) -> Result<(), TransportError> {
144 let _ = (url, bytes, media_type);
145 Err(TransportError::new(
146 "sync.invalid_request",
147 "this transport has no blob put url (§5.9.3)",
148 ))
149 }
150 /// Realtime attach (§8.1). Inbound traffic is delivered by the host via
151 /// `SyncClient::on_realtime_text` / `on_realtime_binary`.
152 fn realtime_connect(&mut self) -> Result<(), TransportError>;
153 /// Client → server JSON control message (acks, §8.2).
154 fn realtime_send(&mut self, text: &str) -> Result<(), TransportError>;
155 fn realtime_close(&mut self) -> Result<(), TransportError>;
156}