121 lines
4.6 KiB
TypeScript
121 lines
4.6 KiB
TypeScript
// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
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import { CompletionMessage, HubMessage, IHubProtocol, InvocationMessage, MessageType, StreamItemMessage } from "./IHubProtocol";
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import { ILogger, LogLevel } from "./ILogger";
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import { TransferFormat } from "./ITransport";
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import { NullLogger } from "./Loggers";
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import { TextMessageFormat } from "./TextMessageFormat";
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const JSON_HUB_PROTOCOL_NAME: string = "json";
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/** Implements the JSON Hub Protocol. */
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export class JsonHubProtocol implements IHubProtocol {
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/** @inheritDoc */
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public readonly name: string = JSON_HUB_PROTOCOL_NAME;
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/** @inheritDoc */
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public readonly version: number = 1;
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/** @inheritDoc */
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public readonly transferFormat: TransferFormat = TransferFormat.Text;
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/** Creates an array of {@link HubMessage} objects from the specified serialized representation.
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*
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* @param {string} input A string containing the serialized representation.
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* @param {ILogger} logger A logger that will be used to log messages that occur during parsing.
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*/
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public parseMessages(input: string, logger: ILogger): HubMessage[] {
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// The interface does allow "ArrayBuffer" to be passed in, but this implementation does not. So let's throw a useful error.
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if (typeof input !== "string") {
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throw new Error("Invalid input for JSON hub protocol. Expected a string.");
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}
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if (!input) {
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return [];
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}
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if (logger === null) {
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logger = NullLogger.instance;
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}
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// Parse the messages
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const messages = TextMessageFormat.parse(input);
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const hubMessages = [];
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for (const message of messages) {
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const parsedMessage = JSON.parse(message) as HubMessage;
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if (typeof parsedMessage.type !== "number") {
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throw new Error("Invalid payload.");
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}
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switch (parsedMessage.type) {
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case MessageType.Invocation:
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this.isInvocationMessage(parsedMessage);
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break;
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case MessageType.StreamItem:
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this.isStreamItemMessage(parsedMessage);
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break;
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case MessageType.Completion:
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this.isCompletionMessage(parsedMessage);
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break;
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case MessageType.Ping:
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// Single value, no need to validate
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break;
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case MessageType.Close:
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// All optional values, no need to validate
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break;
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default:
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// Future protocol changes can add message types, old clients can ignore them
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logger.log(LogLevel.Information, "Unknown message type '" + parsedMessage.type + "' ignored.");
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continue;
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}
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hubMessages.push(parsedMessage);
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}
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return hubMessages;
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}
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/** Writes the specified {@link HubMessage} to a string and returns it.
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*
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* @param {HubMessage} message The message to write.
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* @returns {string} A string containing the serialized representation of the message.
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*/
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public writeMessage(message: HubMessage): string {
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return TextMessageFormat.write(JSON.stringify(message));
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}
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private isInvocationMessage(message: InvocationMessage): void {
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this.assertNotEmptyString(message.target, "Invalid payload for Invocation message.");
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if (message.invocationId !== undefined) {
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this.assertNotEmptyString(message.invocationId, "Invalid payload for Invocation message.");
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}
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}
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private isStreamItemMessage(message: StreamItemMessage): void {
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this.assertNotEmptyString(message.invocationId, "Invalid payload for StreamItem message.");
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if (message.item === undefined) {
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throw new Error("Invalid payload for StreamItem message.");
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}
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}
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private isCompletionMessage(message: CompletionMessage): void {
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if (message.result && message.error) {
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throw new Error("Invalid payload for Completion message.");
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}
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if (!message.result && message.error) {
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this.assertNotEmptyString(message.error, "Invalid payload for Completion message.");
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}
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this.assertNotEmptyString(message.invocationId, "Invalid payload for Completion message.");
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}
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private assertNotEmptyString(value: any, errorMessage: string): void {
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if (typeof value !== "string" || value === "") {
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throw new Error(errorMessage);
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}
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}
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}
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