| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| "use strict"; |
| |
| const http = require("http"); |
| |
| const {StateFun, Message, Context, messageBuilder, egressMessageBuilder} = require("apache-flink-statefun"); |
| |
| // ------------------------------------------------------------------------------------------------------ |
| // Greeter |
| // ------------------------------------------------------------------------------------------------------ |
| |
| const GreetRequestType = StateFun.jsonType("example/GreetRequest"); |
| const EgressRecordType = StateFun.jsonType("io.statefun.playground/EgressRecord") |
| |
| /** |
| * A Stateful function that represents a person. |
| * |
| * @param {Context} context a StateFun context. |
| * @param {Message} message the input message. |
| * @returns {Promise<void>} |
| */ |
| async function person(context, message) { |
| // update the visit count |
| let visits = context.storage.visits; |
| visits += 1; |
| context.storage.visits = visits |
| |
| // enrich the request with the number of vists. |
| let request = message.as(GreetRequestType) |
| request.visits = visits |
| |
| // next, we will forward a message to a special greeter function, |
| // that will compute a super-doper-personalized greeting based on the |
| // number of visits that this person has. |
| context.send(messageBuilder({ |
| typename: "example/greeter", |
| id: request.name, |
| value: request, |
| valueType: GreetRequestType |
| })); |
| } |
| |
| |
| async function greeter(context, message) { |
| const request = message.as(GreetRequestType); |
| const person_name = request.name; |
| const visits = request.visits; |
| |
| const greeting = await compute_fancy_greeting(person_name, visits); |
| const egressRecord = { |
| topic: "greetings", |
| payload: greeting, |
| } |
| |
| context.send(egressMessageBuilder({ |
| typename: "io.statefun.playground/egress", |
| value: egressRecord, |
| valueType: EgressRecordType, |
| })); |
| } |
| |
| |
| async function compute_fancy_greeting(name, seen) { |
| if (seen === 0) { |
| return ""; |
| } else if (seen === 1) { |
| return `Welcome ${name}`; |
| } else if (seen === 2) { |
| return `Nice to see you again ${name}`; |
| } else if (seen === 3) { |
| return `Third time is a charm ${name}`; |
| } else { |
| return `Nice to see you at the ${seen}-nth time ${name}!`; |
| } |
| } |
| |
| |
| // ------------------------------------------------------------------------------------------------------ |
| // Bind all the functions |
| // ------------------------------------------------------------------------------------------------------ |
| |
| let statefun = new StateFun(); |
| |
| statefun.bind({ |
| typename: "example/person", |
| fn: person, |
| specs: [ |
| { |
| name: "visits", |
| type: StateFun.intType(), |
| } |
| ] |
| }); |
| |
| |
| statefun.bind({ |
| typename: "example/greeter", |
| fn: greeter |
| }); |
| |
| // ------------------------------------------------------------------------------------------------------ |
| // Serve all the functions |
| // ------------------------------------------------------------------------------------------------------ |
| |
| http.createServer(statefun.handler()).listen(8000); |