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pubsub-message.ts
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pubsub-message.ts
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import StreamID from '@ceramicnetwork/streamid';
import CID from 'cids';
import { UnreachableCaseError } from '@ceramicnetwork/common';
import dagCBOR from 'ipld-dag-cbor';
import * as multihashes from 'multihashes';
import * as sha256 from '@stablelib/sha256';
import { TextDecoder, TextEncoder } from 'util';
import * as uint8arrays from 'uint8arrays';
/**
* Ceramic Pub/Sub message type.
*/
export enum MsgType {
UPDATE,
QUERY,
RESPONSE,
}
export type UpdateMessage = {
typ: MsgType.UPDATE;
stream: StreamID;
tip: CID;
};
export type QueryMessage = {
typ: MsgType.QUERY;
id: string;
stream: StreamID;
};
export type ResponseMessage = {
typ: MsgType.RESPONSE;
id: string;
tips: Map<string, CID>;
};
export type PubsubMessage = UpdateMessage | QueryMessage | ResponseMessage;
const textEncoder = new TextEncoder()
const textDecoder = new TextDecoder('utf-8')
function messageHash(message: any): string {
// DAG-CBOR encoding
const encoded = dagCBOR.util.serialize(message);
// SHA-256 hash
const id = sha256.hash(encoded);
// Multihash encoding
return uint8arrays.toString(multihashes.encode(id, 'sha2-256'), 'base64url');
}
export function buildQueryMessage(streamId: StreamID): QueryMessage {
const payload = {
typ: MsgType.QUERY as MsgType.QUERY,
stream: streamId,
};
const id = messageHash({...payload, stream: streamId.toString()});
return {
...payload,
id: id,
};
}
export function serialize(message: PubsubMessage): Uint8Array {
switch (message.typ) {
case MsgType.QUERY: {
return textEncoder.encode(JSON.stringify({
...message,
doc: message.stream.toString(), // todo remove once we no longer support interop with nodes older than v1.0.0
stream: message.stream.toString(),
}));
}
case MsgType.RESPONSE: {
const tips = {};
message.tips.forEach((value, key) => (tips[key] = value.toString()));
const payload = {
...message,
tips: tips,
};
return textEncoder.encode(JSON.stringify(payload));
}
case MsgType.UPDATE: {
// todo remove 'doc' once we no longer support interop with nodes older than v1.0.0
const payload = { typ: MsgType.UPDATE, doc: message.stream.toString(), stream: message.stream.toString(), tip: message.tip.toString() };
return textEncoder.encode(JSON.stringify(payload));
}
default:
throw new UnreachableCaseError(message, 'Unknown message type');
}
}
export function deserialize(message: any): PubsubMessage {
const asString = textDecoder.decode(message.data);
const parsed = JSON.parse(asString);
const typ = parsed.typ as MsgType;
switch (typ) {
case MsgType.UPDATE: {
// TODO don't take streamid from 'doc' once we no longer interop with nodes older than v1.0.0
const stream = StreamID.fromString(parsed.stream || parsed.doc)
return {
typ: MsgType.UPDATE,
stream,
tip: new CID(parsed.tip),
};
}
case MsgType.RESPONSE: {
const tips: Map<string, CID> = new Map();
Object.entries<string>(parsed.tips).forEach(([key, value]) => tips.set(key, new CID(value)));
return {
typ: MsgType.RESPONSE,
id: parsed.id,
tips: tips,
};
}
case MsgType.QUERY: {
// TODO don't take streamid from 'doc' once we no longer interop with nodes older than v1.0.0
const stream = StreamID.fromString(parsed.stream || parsed.doc)
return {
typ: MsgType.QUERY,
id: parsed.id,
stream,
};
}
default:
throw new UnreachableCaseError(typ, 'Unknown message type');
}
}