Ucanto UCAN RPC in Golang.
go get github.com/storacha/go-ucantopackage main
import (
"..."
)
// service URL & DID
serviceURL, _ := url.Parse("https://up.web3.storage")
servicePrincipal, _ := did.Parse("did:web:web3.storage")
// HTTP transport and CAR encoding
channel := http.NewHTTPChannel(serviceURL)
conn, _ := client.NewConnection(servicePrincipal, channel)
// private key to sign UCANs with
priv, _ := ioutil.ReadFile("path/to/private.key")
signer, _ := ed25519.Parse(priv)
audience := servicePrincipal
type StoreAddCaveats struct {
Link ipld.Link
Size int
}
func (c StoreAddCaveats) ToIPLD() (datamodel.Node, error) {
return ipld.WrapWithRecovery(&c, StoreAddType())
}
func StoreAddType() ipldschema.Type {
ts, _ := ipldprime.LoadSchemaBytes([]byte(`
type StoreAdd struct {
link Link
size Int
}
`))
return ts.TypeByName("StoreAdd")
}
capability := ucan.NewCapability(
"store/add",
did.Parse("did:key:z6MkwDuRThQcyWjqNsK54yKAmzfsiH6BTkASyiucThMtHt1T").String(),
StoreAddCaveats{
// TODO
},
)
// create invocation(s) to perform a task with granted capabilities
inv, _ := invocation.Invoke(signer, audience, capability, delegation.WithProofs(...))
invocations := []invocation.Invocation{inv}
// send the invocation(s) to the service
resp, _ := client.Execute(invocations, conn)
// define datamodels for ok and error outcome
type OkModel struct {
Status string
}
type ErrModel struct {
Message string
}
// create new receipt reader, passing the IPLD schema for the result and the
// ok and error types
reader, _ := receipt.NewReceiptReader[OkModel, ErrModel]([]byte(`
type Result union {
| Ok "ok"
| Err "error"
} representation keyed
type Ok struct {
status String
}
type Err struct {
message String
}
`))
// get the receipt link for the invocation from the response
rcptlnk, _ := resp.Get(invocations[0].Link())
// read the receipt for the invocation from the response
rcpt, _ := reader.Read(rcptlnk, res.Blocks())
fmt.Println(rcpt.Out().Ok())package main
import (
"..."
)
type TestEcho struct {
Echo string
}
func (c TestEcho) ToIPLD() (ipld.Node, error) {
return ipld.WrapWithRecovery(&c, EchoType())
}
func EchoType() ipldschema.Type {
ts, _ := ipldprime.LoadSchemaBytes([]byte(`
type TestEcho struct {
echo String
}
`))
return ts.TypeByName("TestEcho")
}
func createServer(signer principal.Signer) (server.ServerView, error) {
// Capability definition(s)
testecho := validator.NewCapability(
"test/echo",
schema.DIDString(),
schema.Struct[TestEcho](EchoType(), nil),
validator.DefaultDerives,
)
return server.NewServer(
signer,
// Handler definitions
server.WithServiceMethod(
testecho.Can(),
server.Provide(
testecho,
func(cap ucan.Capability[TestEcho], inv invocation.Invocation, ctx server.InvocationContext) (TestEcho, receipt.Effects, error) {
return TestEcho{Echo: cap.Nb().Echo}, nil, nil
},
),
),
)
}
func main() {
signer, _ := ed25519.Generate()
server, _ := createServer(signer)
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
res, _ := server.Request(uhttp.NewHTTPRequest(r.Body, r.Header))
for key, vals := range res.Headers() {
for _, v := range vals {
w.Header().Add(key, v)
}
}
if res.Status() != 0 {
w.WriteHeader(res.Status())
}
io.Copy(w, res.Body())
})
listener, _ := net.Listen("tcp", ":0")
port := listener.Addr().(*net.TCPAddr).Port
fmt.Printf("{\"id\":\"%s\",\"url\":\"http://127.0.0.1:%d\"}\n", signer.DID().String(), port)
http.Serve(listener, nil)
}Feel free to join in. All welcome. Please open an issue!
Dual-licensed under MIT + Apache 2.0