{"id":786,"date":"2019-07-12T15:56:18","date_gmt":"2019-07-12T13:56:18","guid":{"rendered":"https:\/\/blog.besharp.it\/?p=786"},"modified":"2021-03-17T12:50:33","modified_gmt":"2021-03-17T11:50:33","slug":"realizziamo-un-sistema-di-notifiche-serverless-con-amazon-api-gateway","status":"publish","type":"post","link":"https:\/\/blog.besharp.it\/it\/realizziamo-un-sistema-di-notifiche-serverless-con-amazon-api-gateway\/","title":{"rendered":"Realizziamo un sistema di notifiche Serverless con Amazon API Gateway"},"content":{"rendered":"<p><span style=\"font-weight: 400;\">La diffusione capillare del Cloud computing ha portato, negli ultimi anni, ad una adozione massiva del paradigma di sviluppo applicativo \u201ca microservizi\u201d. La rifattorizzazione di applicazioni monolitiche in microservizi permette infatti di sfruttare al meglio alcune caratteristiche intrinseche del Cloud stesso, tra le quali la presenza di molti servizi di tipo <\/span><i><span style=\"font-weight: 400;\">managed<\/span><\/i><span style=\"font-weight: 400;\">, utili a demandare al Cloud provider la gestione e l\u2019affidabilit\u00e0 di task critici, ma non facenti parte del <\/span><i><span style=\"font-weight: 400;\">core<\/span><\/i><span style=\"font-weight: 400;\"> applicativo.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">beSharp non fa eccezione: questo processo di rifattorizzazione, infatti, ha coinvolto anche <\/span><a href=\"https:\/\/www.noovolari.com\/\"><span style=\"font-weight: 400;\">Noovolari Smart Backup<\/span><\/a><span style=\"font-weight: 400;\"> &#8211; il nostro prodotto per la gestione del Backup e Disaster Recovery di infrastrutture AWS.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">A tal proposito \u00e8 stato particolarmente interessante il refactoring del sistema di notifiche interne all\u2019applicazione, che vengono \u201cpushate\u201d all\u2019interno dell\u2019interfaccia web al verificarsi di specifici eventi, come ad esempio la conclusione di un backup job o l\u2019apertura di una sessione di file-level recovery.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">La soluzione monolitica era basata su Ruby\/<\/span><b>ActionCable <\/b><span style=\"font-weight: 400;\">e<\/span><b> Redis <\/b><span style=\"font-weight: 400;\">e accentrava la gestione degli invii di notifiche in un controller dell\u2019applicazione.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Approfittando del recente rilascio da parte di AWS delle API Websocket per API Gateway, abbiamo deciso di rifattorizzare l\u2019engine di gestione delle notifiche in un microservizio completamente serverless, utilizzando SQS per disaccoppiare l\u2019invio e la ricezione dei messaggi.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Sempre recentemente sono stati introdotti i Lambda Layers e la possibilit\u00e0 di scrivere funzioni Lambda in Ruby (il linguaggio principale con cui \u00e8 sviluppato Noovolari Smart Backup); grazie a queste due feature abbiamo potuto riutilizzare buona parte del codice backend originale, mantenendolo pulito e facilmente integrabile in altre applicazioni.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Questo approccio ci ha dato diversi spunti tecnici che abbiamo deciso di condividere in questo articolo, creando un piccolo tutorial su come realizzare un microservizio di notifiche completamente Serverless basato sui servizi AWS.\u00a0<\/span><\/p>\n<h2>Tecnologie utilizzate<\/h2>\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">Per implementare questa soluzione andremo ad utilizzare i seguenti linguaggi e servizi:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Html e JavaScript (jQuery)<\/span><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">AWS Lambda<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Node.js su AWS Lambda<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Ruby su AWS Lambda<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Amazon API Gateway<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Amazon SQS<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Amazon DynamoDB<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">AWS IAM<\/span><\/li>\n<\/ul>\n<h2><span style=\"font-weight: 400;\">Implementazione lato client<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Per cominciare vediamo come attivare il canale WebSocket con API Gateway mediante l\u2019url che ci verr\u00e0 fornito all\u2019atto della creazione delle API di back-end.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Nel template principale dell\u2019applicazione abbiamo aggiunto la seguente funzione javascript:<\/span><\/p>\n<pre><span style=\"font-weight: 400;\">&lt;<\/span><span style=\"font-weight: 400;\">script<\/span><span style=\"font-weight: 400;\">&gt;<\/span>\r\n<b>$<\/b><span style=\"font-weight: 400;\">(<\/span><b><i>document<\/i><\/b><span style=\"font-weight: 400;\">).<\/span><b>ready<\/b><span style=\"font-weight: 400;\">(<\/span><b>function <\/b><span style=\"font-weight: 400;\">() {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/Setup notification system<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><\/i><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>websocket<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">connect<\/span><span style=\"font-weight: 400;\">(<\/span>\r\n<b>'<\/b><b>&lt;%=<\/b> <b><i>Rails<\/i><\/b><b>.<\/b><b>env <\/b><b>%&gt;<\/b><b>'<\/b><span style=\"font-weight: 400;\">,<\/span>\r\n<b>'<\/b><b>&lt;%=<\/b> <b><i>Notification<\/i><\/b><b>::<\/b><b><i>NotificationAuthorizer<\/i><\/b><b>.<\/b><b>check_token<\/b><b>(<\/b><b>user_id<\/b><b>: <\/b><b>current_user<\/b><b>.<\/b><b>id<\/b><b>, <\/b><b>company_code<\/b><b>: <\/b><b>current_user<\/b><b>.<\/b><b>companies<\/b><b>.<\/b><b>first<\/b><b>.<\/b><b>code<\/b><b>) <\/b><b>%&gt;<\/b><b>'<\/b>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0);<\/span>\r\n<span style=\"font-weight: 400;\">&lt;\/<\/span><span style=\"font-weight: 400;\">script<\/span><span style=\"font-weight: 400;\">&gt;<\/span><\/pre>\n<p><span style=\"font-weight: 400;\">Questa funzione \u00e8 cos\u00ec implementata nel dettaglio:<\/span><\/p>\n<pre><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>websocket<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">connect <\/span><span style=\"font-weight: 400;\">= <\/span><b>function<\/b><span style=\"font-weight: 400;\">(stage, token) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b>var <\/b><span style=\"font-weight: 400;\">socketUrl <\/span><span style=\"font-weight: 400;\">= <\/span><b>'wss:\/\/<\/b><b>&lt;WEBSOCKET_URL&gt;<\/b><b>\/'<\/b><span style=\"font-weight: 400;\">+stage+<\/span><b>'?token='<\/b><span style=\"font-weight: 400;\">+token;\r\n<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ connecting to the websocket url and retrieve function for connect and disconnect<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b>websocket <\/b><span style=\"font-weight: 400;\">=\u00a0 <\/span><b>new <\/b><b><i>WebSocket<\/i><\/b><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">socketUrl<\/span><span style=\"font-weight: 400;\">);\r\n<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>websocket<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">onopen <\/span><span style=\"font-weight: 400;\">= <\/span><b>function <\/b><span style=\"font-weight: 400;\">() {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b><i>console<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">info<\/span><span style=\"font-weight: 400;\">(<\/span><b>'socket connection opened properly with...'<\/b><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0};<\/span>\r\n\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>websocket<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">onclose <\/span><span style=\"font-weight: 400;\">= <\/span><b>function <\/b><span style=\"font-weight: 400;\">() {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ websocket is closed.<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i><b><i>console<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">info<\/span><span style=\"font-weight: 400;\">(<\/span><b>\"Connection closed...\"<\/b><span style=\"font-weight: 400;\">);<\/span>\r\n\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0};<\/span>\r\n\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b><i>noovolari<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>smartbackup<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b><i>websocket<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">onmessage <\/span><span style=\"font-weight: 400;\">= <\/span><b>function <\/b><span style=\"font-weight: 400;\">(evt) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b>var <\/b><span style=\"font-weight: 400;\">notification <\/span><span style=\"font-weight: 400;\">= <\/span><b><i>JSON<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">parse<\/span><span style=\"font-weight: 400;\">(evt.<\/span><b>data<\/b><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b>var <\/b><span style=\"font-weight: 400;\">message <\/span><span style=\"font-weight: 400;\">= <\/span><span style=\"font-weight: 400;\">notification<\/span><span style=\"font-weight: 400;\">.<\/span><b>data<\/b><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b>noovolariUiToolkit<\/b><span style=\"font-weight: 400;\">.<\/span><b><i>notifications<\/i><\/b><span style=\"font-weight: 400;\">.<\/span><b>subscribers<\/b><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">forEach<\/span><span style=\"font-weight: 400;\">(<\/span><b>function<\/b><span style=\"font-weight: 400;\">(subscriber) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><b>if<\/b><span style=\"font-weight: 400;\">(subscriber.<\/span><b>type <\/b><span style=\"font-weight: 400;\">=== <\/span><span style=\"font-weight: 400;\">message<\/span><span style=\"font-weight: 400;\">.<\/span><b>type<\/b><span style=\"font-weight: 400;\">) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0subscriber.<\/span><span style=\"font-weight: 400;\">callback<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">message<\/span><span style=\"font-weight: 400;\">.<\/span><b>data<\/b><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0});<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0};<\/span>\r\n<span style=\"font-weight: 400;\">};\r\n<\/span><\/pre>\n<p><span style=\"font-weight: 400;\">Andiamo ad analizzare il codice passo-passo.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Con questa funzione andiamo a definire tutti e tre i metodi necessari ad implementare l\u2019interfaccia dell\u2019oggetto WebSocket di Javascript; si nota che dall\u2019esterno passiamo sia la variabile \u201cstage\u201d che identifica per quale ambiente di lavoro vogliamo aprire la comunicazione, sia esso <\/span><b>development <\/b><span style=\"font-weight: 400;\">che <\/span><b>production<\/b><span style=\"font-weight: 400;\">, sia la variabile token che, per sicurezza, viene generata da codice Ruby in modo da non dare la possibilit\u00e0 di fare inspect della funzione (gli inspector dei browser possono sempre mostrare il codice Javascript, invece in questo modo il token ci arriva gi\u00e0 generato dal back-end).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Le callback di apertura e chiusura della connessione WebSocket vengono gestite direttamente da AWS, vedremo poi come.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Sulla ricezione del messaggio invece cicliamo sul numero di \u201csubscriber\u201d, che abbiamo registrato prima dell\u2019apertura del canale, per rappresentare il messaggio con una callback dello stesso tipo del messaggio stesso (ad esempio: un messaggio di informazione, uno di allerta, uno di pericolo, etc.)<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">Il <\/span><b>token <\/b><span style=\"font-weight: 400;\">\u00e8 un JWT Token crittografato con SHA512, il secret condiviso \u00e8 gestito mediante\u00a0<\/span><span style=\"font-weight: 400;\">variabile d\u2019ambiente nella nostra applicazione e su AWS.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Vediamo come viene costruito (il linguaggio di riferimento \u00e8 Ruby):<\/span><\/p>\n<pre><b>def self<\/b><span style=\"font-weight: 400;\">.<\/span><b><i>generate_token<\/i><\/b><span style=\"font-weight: 400;\">(<\/span><i><span style=\"font-weight: 400;\">user_id<\/span><\/i><span style=\"font-weight: 400;\">:, <\/span><i><span style=\"font-weight: 400;\">company_code<\/span><\/i><span style=\"font-weight: 400;\">:)<\/span>\r\n<i><span style=\"font-weight: 400;\">token <\/span><\/i><span style=\"font-weight: 400;\">= compose_token(<\/span><b>user_id<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">user_id<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b>company_code<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">company_code<\/span><\/i><span style=\"font-weight: 400;\">)<\/span>\r\n<i><span style=\"font-weight: 400;\">payload <\/span><\/i><span style=\"font-weight: 400;\">= { <\/span><b>user_id<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">user_id<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b>room_id<\/b><span style=\"font-weight: 400;\">:<\/span><i><span style=\"font-weight: 400;\">company_code<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b>token<\/b><span style=\"font-weight: 400;\">:<\/span><i><span style=\"font-weight: 400;\">token<\/span><\/i><span style=\"font-weight: 400;\">,<\/span><b>exp<\/b><span style=\"font-weight: 400;\">: <\/span><b><i>Time<\/i><\/b><span style=\"font-weight: 400;\">.now.to_i + <\/span><b><i>EXPIRATION_TIME_IN_SECONDS <\/i><\/b><span style=\"font-weight: 400;\">}<\/span>\r\n<b><i>JWT<\/i><\/b><span style=\"font-weight: 400;\">.encode <\/span><i><span style=\"font-weight: 400;\">payload<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b><i>Configuration<\/i><\/b><span style=\"font-weight: 400;\">.load_secrets[<\/span><b>'bernie'<\/b><span style=\"font-weight: 400;\">][<\/span><b>'notification_key'<\/b><span style=\"font-weight: 400;\">], <\/span><b>'HS512'<\/b>\r\n<b>End\r\n<\/b><\/pre>\n<pre><b>def self.<\/b><b><i>compose_token<\/i><\/b><b>(<\/b><b><i>user_id<\/i><\/b><b>:, <\/b><b><i>company_code<\/i><\/b><b>:)<\/b>\r\n<b><i>\u00a0\u00a0\u00a0\u00a0\u00a0dynamo <\/i><\/b><b>= get_dynamo_client()<\/b>\r\n<b><i>\u00a0\u00a0\u00a0\u00a0\u00a0token <\/i><\/b><b>= <\/b><b>\"<\/b><b>#{<\/b><b><i>user_id<\/i><\/b><b>}#{<\/b><b><i>Configuration<\/i><\/b><b>.load_secrets[<\/b><b>'bernie'<\/b><b>][<\/b><b>'notification_passcode'<\/b><b>]<\/b><b>}#{<\/b><b><i>company_code<\/i><\/b><b>}<\/b><b>\"<\/b>\r\n<b><i>\u00a0\u00a0\u00a0\u00a0\u00a0token <\/i>= <i>Digest<\/i>::<i>SHA256<\/i>.hexdigest(<i>token<\/i>)\r\n<\/b><\/pre>\n<pre><b><i>dynamo<\/i><\/b><b>.put_item({<\/b>\r\n<b>\u00a0\u00a0<\/b><b>table_name<\/b><b>: <\/b><b><i>Configuration<\/i><\/b><b>.load_secrets[<\/b><b>'bernie'<\/b><b>][<\/b><b>'notification_table'<\/b><b>],<\/b>\r\n<b>\u00a0\u00a0<\/b><b>item<\/b><b>: {<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0<\/b><b>'user_id' <\/b><b><i>=&gt; <\/i><\/b><b><i>user_id<\/i><\/b><b>.to_s,<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0<\/b><b>'room_id' <\/b><b><i>=&gt; <\/i><\/b><b><i>company_code<\/i><\/b><b>,<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0<\/b><b>'token' <\/b><b><i>=&gt; <\/i><\/b><b><i>BCrypt<\/i><\/b><b>::<\/b><b><i>Password<\/i><\/b><b>.create(<\/b><b><i>token<\/i><\/b><b>)<\/b>\r\n<b> \u00a0}<\/b>\r\n<b> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0})<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0return <\/b><b><i>token<\/i><\/b>\r\n<b>end\r\n<\/b><\/pre>\n<p><span style=\"font-weight: 400;\">La funzione \u201cgenerate_token\u201d non solo crea il nostro token mediante la libreria di JWT ma salva anche il token crittografato con il segreto condiviso su DynamoDB, questo ci permette di avere due livelli di sicurezza, il primo dato da JWT che crittografa con SHA512 e il secondo dato da noi con BCrypt.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Implementazione lato AWS<\/span><\/h2>\n<h4><b>\u00a0<\/b><b>API GATEWAY<\/b><\/h4>\n<p><b><span style=\"font-weight: 400;\">Accediamo al nostro account AWS e cerchiamo il servizio<\/span> API Gateway<span style=\"font-weight: 400;\">. Apriamo la pagina del servizio e creiamo una nuova API.<\/span><\/b><span style=\"font-weight: 400;\"> <img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-791 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-5.png\" alt=\"\" width=\"781\" height=\"474\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-5.png 781w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-5-400x243.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-5-768x466.png 768w\" sizes=\"(max-width: 781px) 100vw, 781px\" \/><\/span><\/p>\n<p><span style=\"font-weight: 400;\">Utilizziamo questi parametri:<\/span><\/p>\n<p><span style=\"font-weight: 400;\">&#8211;<\/span><span style=\"font-weight: 400;\"> \u00a0 \u00a0 \u00a0 <\/span><b>WebSocket: <\/b><span style=\"font-weight: 400;\">si usa per passare dalla creazione di una API Http standard ad una di tipo <\/span><b>WebSocket<\/b><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">&#8211;<\/span><span style=\"font-weight: 400;\"> \u00a0 \u00a0 \u00a0 <\/span><b>API name: <\/b><span style=\"font-weight: 400;\">possiamo utilizzare il nome che vogliamo ma ricordiamoci di annotarlo, ci servir\u00e0.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">&#8211;<\/span><span style=\"font-weight: 400;\"> \u00a0 \u00a0 \u00a0 <\/span><b>$request.body.action: <\/b><span style=\"font-weight: 400;\">fa riferimento al nome della chiave JSON che conterr\u00e0 l\u2019azione da chiamare per inviare un messaggio sul canale WebSocket<\/span><b>. <\/b><span style=\"font-weight: 400;\">Ad esempio:<\/span><b>\u00a0 <\/b><span style=\"font-weight: 400;\">&#8220;action&#8221;<\/span><span style=\"font-weight: 400;\">:<\/span><span style=\"font-weight: 400;\">&#8220;sendMessage&#8221;<\/span> <span style=\"font-weight: 400;\">utilizzer\u00e0 <\/span><b>action <\/b><span style=\"font-weight: 400;\">come da parametro specificato ed invocher\u00e0 \u201csendMessage\u201d come lambda per la gestione del messaggio.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">Non appena l\u2019API \u00e8 creata sotto la voce \u201cRoutes\u201d troveremo $connect, $disconnect e $default; le prime due sono molto importanti perch\u00e8 con esse andremo a gestire le fasi di connessione e disconnessione del canale WebSocket sia lato AWS (con le lambda function)\u00a0 sia lato client (come abbiamo visto negli script precedenti).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Clicchiamo su <\/span><b>$connect <\/b><span style=\"font-weight: 400;\">e settiamo i parametri come nell\u2019immagine sottostante:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-793 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-6.png\" alt=\"\" width=\"1002\" height=\"387\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-6.png 1002w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-6-400x154.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-6-768x297.png 768w\" sizes=\"(max-width: 1002px) 100vw, 1002px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Vogliamo collegare la fase di<\/span><b> $connect <\/b><span style=\"font-weight: 400;\">con una funzione lambda, quindi la spuntiamo alla voce \u201cIntegration type\u201d; spuntiamo anche \u201cLambda Proxy Integration\u201d perch\u00e8 vogliamo che la nostra variabile<\/span><b> context <\/b><span style=\"font-weight: 400;\">contenga la lista completa delle propriet\u00e0 della chiamata ad API Gateway.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">La Regione va settata secondo le proprie esigenze, nel nostro caso <\/span><b>eu-west-1<\/b><span style=\"font-weight: 400;\">, \u201clambda function\u201d rappresenta il nome della lambda da richiamare, possiamo caricarlo dal men\u00f9 a tendina. Usiamo il valore di default e salviamo.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Facciamo lo stesso per <\/span><b>$disconnect<\/b><span style=\"font-weight: 400;\"> e<\/span><b> sendMessage<\/b><span style=\"font-weight: 400;\"> puntando alle rispettive funzioni Lambda.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">Se avete eseguito i passaggi correttamente vi ritroverete nella seguente situazione:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-795 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-7.png\" alt=\"\" width=\"654\" height=\"402\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-7.png 654w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-7-400x246.png 400w\" sizes=\"(max-width: 654px) 100vw, 654px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Ora abbiamo quattro rotte configurate con le corrispondenti Lambda, dobbiamo creare i ruoli IAM per farle comunicare con i servizi necessari. Oltre a ci\u00f2 creiamo anche le tabelle di DynamoDB.\u00a0<\/span><\/p>\n<h4><span style=\"font-weight: 400;\">\u00a0<\/span><b>IAM<\/b><\/h4>\n<p><span style=\"font-weight: 400;\">Prima di tutto creiamo quattro ruoli IAM:<\/span><b> OnConnectFunctionRole<\/b><span style=\"font-weight: 400;\">,<\/span><b> OnDisconnectFunctionRole<\/b><span style=\"font-weight: 400;\">,<\/span><b> SendMessageFunctionRole.<\/b><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-797 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-8.png\" alt=\"\" width=\"1002\" height=\"87\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-8.png 1002w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-8-400x35.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-8-768x67.png 768w\" sizes=\"(max-width: 1002px) 100vw, 1002px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Diamogli il nome che preferiamo; per utilizzare la funzione di OnConnect abbiamo bisogno di un<\/span><b>\u00a0 \u201cLambdaBasicExecutionRole\u201d <\/b><span style=\"font-weight: 400;\">e una<\/span><b> \u201ccustom policy\u201d <\/b><span style=\"font-weight: 400;\">con questo json:<\/span><\/p>\n<pre><i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\"Statement\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Action\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:GetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DeleteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:PutItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Scan\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Query\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:UpdateItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:BatchWriteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:BatchGetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DescribeTable\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">  \"Resource\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\/index\/*\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Effect\": \"Allow\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">]<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">}<\/span><\/i><\/pre>\n<p><span style=\"font-weight: 400;\">Ricordiamoci di cambiare <\/span><b>&lt;ACCOUNT_ID&gt;<\/b><span style=\"font-weight: 400;\"> con il nostro account id e di prendere nota del fatto che \u201c<\/span><b>hermesConnections<\/b><span style=\"font-weight: 400;\">\u201d rappresenta la nostra tabella di dynamodb.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">Per<\/span><b> \u201cOnDisconnect\u201d:<\/b><\/p>\n<pre><i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\"Statement\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Action\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:GetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DeleteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:PutItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Scan\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Query\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:UpdateItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\"> \"dynamodb:BatchWriteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:BatchGetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DescribeTable\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Resource\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\/index\/*\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Effect\": \"Allow\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">]<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">}<\/span><\/i><\/pre>\n<p><span style=\"font-weight: 400;\">Per<\/span><b> \u201cSendMessage\u201d <\/b><span style=\"font-weight: 400;\">utilizziamo ancora un \u201c<\/span><b>LambdaBasicExecutionRole<\/b><span style=\"font-weight: 400;\">\u201d, AWSLambdaSQSQueueExecutionRole e tre custom policies:<\/span><\/p>\n<pre><b><i>{<\/i><\/b>\r\n<i><span style=\"font-weight: 400;\">\"Statement\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Action\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:GetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DeleteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:PutItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Scan\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"dynamodb:Query\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:UpdateItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:BatchWriteItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:BatchGetItem\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"dynamodb:DescribeTable\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Resource\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"arn:aws:dynamodb:eu-west-1:&lt;ACCOUNT_ID&gt;:table\/hermesConnections\/index\/*\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Effect\": \"Allow\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">]<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n\r\n<\/pre>\n<p>Quest\u2019altra:<\/p>\n<pre><i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\"Statement\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Action\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"sqs:ChangeMessageVisibility\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"sqs:ChangeMessageVisibilityBatch\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i>    <i><span style=\"font-weight: 400;\">\"sqs:DeleteMessage\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"sqs:DeleteMessageBatch\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i>    <i><span style=\"font-weight: 400;\">\"sqs:GetQueueAttributes\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i>    <i><span style=\"font-weight: 400;\">\"sqs:ReceiveMessage\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Resource\": \"arn:aws:sqs:eu-west-1:&lt;ACCOUNT_ID&gt;:hermes-messageQueue\",<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Effect\": \"Allow\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">]<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">}<\/span><\/i><\/pre>\n<p>Infine:<\/p>\n<pre><i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\"Statement\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">{<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\"> \u00a0 \"Action\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"execute-api:ManageConnections\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Resource\": [<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\"arn:aws:execute-api:eu-west-1:&lt;ACCOUNT_ID&gt;:&lt;API_CODE&gt;\/*\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">],<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">\"Effect\": \"Allow\"<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><\/i> <i><span style=\"font-weight: 400;\">}<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">]<\/span><\/i>\r\n<i><span style=\"font-weight: 400;\">}<\/span><\/i><\/pre>\n<p><span style=\"font-weight: 400;\">La voce<\/span><b> &lt;API_CODE&gt; <\/b><span style=\"font-weight: 400;\">pu\u00f2 essere recuperata dalla schermata di API Gateway in alto a sinistra:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-799 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-9.png\" alt=\"\" width=\"441\" height=\"131\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-9.png 441w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Picture1-9-400x119.png 400w\" sizes=\"(max-width: 441px) 100vw, 441px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Ora possiamo creare la tabella di DynamoDB per salvare le connectionID che ci vengono fornite da API Gateway durante la <\/span><b>$connect<\/b><span style=\"font-weight: 400;\">. Questo parametro \u00e8 molto importante perch\u00e8 identificano l\u2019utente che ha aperto la connessione. Vedremo poi come autenticare la richiesta di apertura della connessione, ma anche come filtrare l\u2019invio dei messaggi per ROOM.<\/span><\/p>\n<h4><b>DYNAMODB<\/b><\/h4>\n<p><span style=\"font-weight: 400;\">Connettiamoci al servizio di DynamoDB e clicchiamo \u201ccreate table\u201d, ci ritroveremo nella situazione in figura:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-801 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-2.png\" alt=\"\" width=\"385\" height=\"512\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-2.png 385w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-2-226x300.png 226w\" sizes=\"(max-width: 385px) 100vw, 385px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Settiamo come nome lo stesso che abbiamo impostato negli IAM role precedentemente, in questo caso \u201chermesConnections\u201d; come <\/span><b>partition key <\/b><span style=\"font-weight: 400;\">settiamo <\/span><b>connetion_id<\/b><span style=\"font-weight: 400;\"> di tipo <\/span><b>stringa<\/b><span style=\"font-weight: 400;\">, per i settaggi della tabella lasciamo la spunta di <\/span><b>default<\/b><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">La tabella verr\u00e0 creata in pochi secondi, man mano che gli utenti si collegheranno ad API Gateway la funzione associata a $connect creer\u00e0 delle tuple in questa tabella.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Ora passiamo a definire le nostre funzioni lambda a partire dalle rotte create precedentemente su API Gateway.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Lambda per $connect e authorizer<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Andiamo alla pagina di gestione delle funzioni Lambda e creiamo una nuova funzione.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-803 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-12.44.59-1024x101.png\" alt=\"\" width=\"1024\" height=\"101\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-12.44.59-1024x101.png 1024w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-12.44.59-400x39.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-12.44.59-768x75.png 768w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-12.44.59.png 1140w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Diamo il nome che abbiamo utilizzato all\u2019<\/span><b>atto di creazione della rotta di $connect<\/b><span style=\"font-weight: 400;\">, poi impostiamo i seguenti valori come da figura:<\/span><\/p>\n<p><b>app.js<\/b><\/p>\n<pre><b>var<\/b><b> AWS = require(<\/b><b>\"aws-sdk\"<\/b><b>);<\/b>\r\n<b>AWS.config.update({ region: process.env.AWS_REGION });<\/b>\r\n<b>var<\/b><b> DDB = <\/b><b>new<\/b><b> AWS.DynamoDB({ apiVersion: <\/b><b>\"2012-10-08\"<\/b><b> });\r\n\r\n<\/b><\/pre>\n<pre><b>exports.handler = <\/b><b>function<\/b><b> (event, context, callback) {<\/b>\r\n<b>\u00a0\u00a0<\/b><b><i>\/\/ based on query string parameter on the connection websocket add the connection in the dynamo table with the selected room_id and user_id<\/i><\/b>\r\n<b> \u00a0console.log(event.requestContext.stage);<\/b>\r\n<b>\u00a0\u00a0<\/b><b>let<\/b><b> table = event.requestContext.table_name;<\/b>\r\n<b>\u00a0\u00a0<\/b><b>var<\/b><b> putParams = {<\/b>\r\n<b> \u00a0\u00a0\u00a0TableName: process.env[table],<\/b>\r\n<b> \u00a0\u00a0\u00a0Item: {<\/b>\r\n<b> \u00a0\u00a0\u00a0\u00a0\u00a0room_id: {S: event.requestContext.authorizer.room_id},<\/b>\r\n<b> \u00a0\u00a0\u00a0\u00a0\u00a0connection_id: { S: event.requestContext.connectionId },<\/b>\r\n<b> \u00a0\u00a0\u00a0\u00a0\u00a0user_id: {S: event.requestContext.authorizer.user_id}<\/b>\r\n<b> \u00a0\u00a0\u00a0}<\/b>\r\n<b>\u00a0\u00a0};<\/b>\r\n\r\n<b><\/b><\/pre>\n<pre><b>DDB.putItem(putParams, <\/b><b>function<\/b><b> (err) {<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0callback(<\/b><b>null<\/b><b>, {<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statusCode: err ? <\/b><b>500<\/b><b> : <\/b><b>200<\/b><b>,<\/b>\r\n<b>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0body: err ? <\/b><b>\"Failed to connect: \"<\/b><b> + JSON.stringify(err) : <\/b><b>\"Connected.\"<\/b>\r\n<b> \u00a0\u00a0\u00a0});<\/b>\r\n<b> \u00a0});<\/b>\r\n<b>};\r\n<\/b><\/pre>\n<p><b>package.json<\/b><\/p>\n<pre><span style=\"font-weight: 400;\">{<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"name\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"onConnect\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"version\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"1.0.0\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"description\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"OnConnect function for WebSockets on API Gateway\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"main\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"src\/app.js\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"author\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"SAM CLI\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"license\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"MIT\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"dependencies\"<\/span><span style=\"font-weight: 400;\">: {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"aws-sdk\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"^2.434.0\"<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0} <\/span>\r\n<span style=\"font-weight: 400;\">}<\/span><\/pre>\n<p>Come environment variables inseriamo il nome della tabella delle connessioni:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-807 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-16.54.41.png\" alt=\"\" width=\"937\" height=\"187\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-16.54.41.png 937w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-16.54.41-400x80.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-16.54.41-768x153.png 768w\" sizes=\"(max-width: 937px) 100vw, 937px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Aggiungiamo anche la Lambda di Authorizer:<\/span><\/p>\n<p><b>index.js<\/b><\/p>\n<pre><span style=\"font-weight: 400;\">exports.handler = async (event) =&gt; {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">try<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0console.log(event.requestContext.stage);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ Query string parameters you can use to validate the connection<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ We verify the json Web Token<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> jwt = require(<\/span><span style=\"font-weight: 400;\">'jsonwebtoken'<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> secret_environment = <\/span><span style=\"font-weight: 400;\">'JWT_SECRET'<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> table_environment = <\/span><span style=\"font-weight: 400;\">'TABLE_NAME'<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> decoded = jwt.verify(event.queryStringParameters.token, process.env[secret_environment]);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> userId = decoded.user_id;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> roomId = decoded.room_id;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> token\u00a0 = decoded.token;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ The principal id\u00a0 can be anything, in this case we used <\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> principalId = userId;\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">        const<\/span><span style=\"font-weight: 400;\"> AWS = require(<\/span><span style=\"font-weight: 400;\">'aws-sdk'<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0const ddb = new AWS.DynamoDB({ apiVersion: '2012-08-10' });\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> db_token, db_user_id, db_room_id, db_expire_date;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> params = {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0TableName: process.env[table_environment],<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Key: {\u00a0<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0user_id: { S: userId.toString() },<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0room_id: { S: roomId.toString() }\u00a0<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0};<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0await ddb.getItem(params, <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\">(err, data) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">if<\/span><span style=\"font-weight: 400;\"> (err) { <\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/* an error occurred *\/<\/span><\/i> \r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0console.log(err, err.stack);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">else<\/span><span style=\"font-weight: 400;\"> { <\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ successful response<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db_user_id = data.Item.user_id.S;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db_room_id = data.Item.room_id.S;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0db_token = data.Item.token.S;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}).promise();\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> bcrypt = require(<\/span><span style=\"font-weight: 400;\">\"bcryptjs\"<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> compare_hash = bcrypt.compareSync(token, db_token);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> compare_user_and_room = db_room_id.toString() === roomId.toString() &amp;&amp; db_user_id.toString() === userId.toString();<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> effect = (compare_hash &amp;&amp; compare_user_and_room) ? <\/span><span style=\"font-weight: 400;\">'Allow'<\/span><span style=\"font-weight: 400;\"> : <\/span><span style=\"font-weight: 400;\">'Deny'<\/span><span style=\"font-weight: 400;\">; <\/span><i><span style=\"font-weight: 400;\">\/\/ Set 'Allow' or 'Deny' to decide if one can connect or not<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0console.log(effect);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> generatePolicy(principalId, effect, event.methodArn, userId, roomId);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">catch<\/span><span style=\"font-weight: 400;\">(e) {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0console.log(e.stack);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span> <span style=\"font-weight: 400;\">null<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">};\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> generatePolicy = <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\">(principalId, effect, resource, user_id, room_id) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ Required output:<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> authResponse = {};<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0authResponse.principalId = principalId;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">if<\/span><span style=\"font-weight: 400;\"> (effect &amp;&amp; resource) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> policyDocument = {};<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0policyDocument.Version = <\/span><span style=\"font-weight: 400;\">'2012-10-17'<\/span><span style=\"font-weight: 400;\">; <\/span><i><span style=\"font-weight: 400;\">\/\/ default version<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0policyDocument.Statement = [];<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> statementOne = {};<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statementOne.Action = <\/span><span style=\"font-weight: 400;\">'execute-api:Invoke'<\/span><span style=\"font-weight: 400;\">; <\/span><i><span style=\"font-weight: 400;\">\/\/ default action<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statementOne.Effect = effect;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statementOne.Resource = resource;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0policyDocument.Statement[<\/span><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\">] = statementOne;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0authResponse.policyDocument = policyDocument;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ Optional output with custom properties of the String, Number or Boolean type.<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0authResponse.context = {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0room_id: room_id,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0user_id: user_id<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0};\u00a0<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> authResponse;<\/span>\r\n<span style=\"font-weight: 400;\">}\r\n<b><\/b><\/span><\/pre>\n<p><strong>package.json<\/strong><\/p>\n<pre><span style=\"font-weight: 400;\">{<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"name\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"authorizer\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"version\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"1.0.0\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"description\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"Authorizer function for WebSockets on API Gateway\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"main\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"index.js\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"author\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"beSharp\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"license\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"MIT\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"dependencies\"<\/span><span style=\"font-weight: 400;\">: {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"bcryptjs\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"^2.4.3\"<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">\"jsonwebtoken\"<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">\"^8.5.1\"<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">}<\/span><\/pre>\n<p>E le variabili di ambiente:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-809 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-3.png\" alt=\"\" width=\"512\" height=\"125\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-3.png 512w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/unnamed-3-400x98.png 400w\" sizes=\"(max-width: 512px) 100vw, 512px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">La Lambda di autorizzazione accede al JWT Token inviato attraverso API Gateway, lo decodifica, ottiene il token crittografato con BCrypt sull\u2019applicazione client che ha aperto la connessione, quindi lo confronta con il token crittografato salvato su DynamoDB, se coincidono, l\u2019authorizer da il permesso di aprire la connessione mediante la creazione di una policy IAM di autorizzazione ad hoc.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Ritorniamo alla schermata di API Gateway e cliccando su <\/span><b>$connect<\/b><span style=\"font-weight: 400;\"> andiamo ad editare il campo <\/span><b>authorizer<\/b><span style=\"font-weight: 400;\"> aggiungendo la lambda appena creata.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-811 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.39.54.png\" alt=\"\" width=\"709\" height=\"303\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.39.54.png 709w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.39.54-400x171.png 400w\" sizes=\"(max-width: 709px) 100vw, 709px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Dove \u201c<\/span><b>websocketAuth<\/b><span style=\"font-weight: 400;\">\u201d \u00e8 il nome che abbiamo dato alla Lambda di autorizzazione.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Ora dobbiamo aggiungere le lambda di <\/span><b>$disconnect<\/b><span style=\"font-weight: 400;\">, <\/span><b>sendMessage<\/b><span style=\"font-weight: 400;\">; procediamo dunque ad aggiungerle partendo da $disconnect che \u00e8 molto semplice:<\/span><\/p>\n<p><b>app.js <\/b><\/p>\n<pre><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> AWS = require(<\/span><span style=\"font-weight: 400;\">\"aws-sdk\"<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">AWS.config.update({ region: process.env.AWS_REGION });<\/span>\r\n<span style=\"font-weight: 400;\">var DDB = new AWS.DynamoDB({ apiVersion: \"2012-10-08\" });\u00a0\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">exports.handler = <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\"> (event, context, callback) {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0console.log(event.requestContext.stage);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> table_environment = <\/span><span style=\"font-weight: 400;\">'TABLE_NAME_'<\/span><span style=\"font-weight: 400;\"> + event.requestContext.stage.toUpperCase();<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> deleteParams = {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0TableName: process.env[table_environment],<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0Key: {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0connection_id: { S: event.requestContext.connectionId }<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0};\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">DDB.deleteItem(deleteParams, <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\"> (err) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0callback(<\/span><span style=\"font-weight: 400;\">null<\/span><span style=\"font-weight: 400;\">, {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statusCode: err ? <\/span><span style=\"font-weight: 400;\">500<\/span><span style=\"font-weight: 400;\"> : <\/span><span style=\"font-weight: 400;\">200<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0body: err ? <\/span><span style=\"font-weight: 400;\">\"Failed to disconnect: \"<\/span><span style=\"font-weight: 400;\"> + JSON.stringify(err) : <\/span><span style=\"font-weight: 400;\">\" Disconnected.\"<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0});<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0});<\/span>\r\n<span style=\"font-weight: 400;\">};\r\n<\/span><\/pre>\n<p><span style=\"font-weight: 400;\">In pratica ogni qualvolta API Gateway deve scollegare un utente dal canale, invoca la funzione associata alla $disconnect che provvede ad eliminare la riga corrispondente alla connection_id dalla tabella delle connessioni di DynamoDB.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Passiamo ora all\u2019invio dei messaggi con <b>sendMessage:<\/b><br \/>\n<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-813 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.58.55-1024x371.png\" alt=\"\" width=\"1024\" height=\"371\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.58.55-1024x371.png 1024w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.58.55-400x145.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.58.55-768x278.png 768w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-18-at-18.58.55.png 1261w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Per prima cosa in questa funzione dobbiamo aggiungere SQS come trigger perch\u00e8 verr\u00e0 richiamata non solo da API Gateway ma anche da SQS. Aggiungiamo SQS come da figura.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Fatto questo passiamo al codice della funzione:<\/span><\/p>\n<p><b>index.js<\/b><\/p>\n<pre><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> AWS = require(<\/span><span style=\"font-weight: 400;\">'aws-sdk'<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">require(<\/span><span style=\"font-weight: 400;\">'.\/patch.js'<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> ddb = <\/span><span style=\"font-weight: 400;\">new<\/span><span style=\"font-weight: 400;\"> AWS.DynamoDB.DocumentClient({ apiVersion: <\/span><span style=\"font-weight: 400;\">'2012-08-10'<\/span><span style=\"font-weight: 400;\"> });<\/span>\r\n<span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> dynamodb = <\/span><span style=\"font-weight: 400;\">new<\/span><span style=\"font-weight: 400;\"> AWS.DynamoDB({apiVersion: <\/span><span style=\"font-weight: 400;\">'2011-12-05'<\/span><span style=\"font-weight: 400;\">});<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> { ENDPOINT } = process.env;<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">exports.handler = async (event, context,callback) =&gt; {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> environment =<\/span><span style=\"font-weight: 400;\">undefined<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> table = process.env.TABLE_NAME;\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> user_id= <\/span><span style=\"font-weight: 400;\">undefined<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> room_id = <\/span><span style=\"font-weight: 400;\">undefined<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> postData = <\/span><span style=\"font-weight: 400;\">undefined<\/span><span style=\"font-weight: 400;\">;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0let messageBody = {};\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ if there are records we re in the sqs trigger put the event from the message of the SQS message received.<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">if<\/span><span style=\"font-weight: 400;\"> (event.Records != <\/span><span style=\"font-weight: 400;\">undefined<\/span><span style=\"font-weight: 400;\">) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> body = JSON.parse(event.Records[<\/span><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\">].body);<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0user_id = body.user_id;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0room_id = body.room_id;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0messageBody = {user_id: user_id };<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0postData = body.data;\u00a0\u00a0\u00a0\u00a0<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">else<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0postData = JSON.parse(event.body).data;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\">  connection_sender =\u00a0 event.requestContext.connectionId;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ get sender info on dynamo db table of connections\r\n<\/span><\/i><\/pre>\n<pre><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> params = {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0Key: {\u00a0 HashKeyElement:\u00a0 { S: connection_sender } },\u00a0<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0TableName:\u00a0 table<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0};<\/span>\r\n<i><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0let sender_item = undefined;\r\n<\/span><\/i><\/pre>\n<pre><span style=\"font-weight: 400;\">\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/get the row of dynamo referred to the connection_id sender.<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0await dynamodb.getItem(params, <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\">(err, data) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">if<\/span><span style=\"font-weight: 400;\"> (err) console.log(err, err.stack); <\/span><i><span style=\"font-weight: 400;\">\/\/ an error occurred<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">else<\/span><span style=\"font-weight: 400;\">  \u00a0 {\u00a0<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0sender_item = data;\u00a0\u00a0<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0user_id = sender_item.Item.user_id.S;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0room_id = sender_item.Item.room_id.S;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ adding in the messageBody the user_id of the sender<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0messageBody = {user_id: user_id };<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}\u00a0 <\/span><i><span style=\"font-weight: 400;\">\/\/ successful response<\/span><\/i>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0}).promise();<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0}\r\n<\/span><\/pre>\n<pre><i><span style=\"font-weight: 400;\">\/\/retrieve all connection for the selected room_id.<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> connectionData;<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">try<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">let<\/span><span style=\"font-weight: 400;\"> scanParam = { TableName: table, ProjectionExpression: <\/span><span style=\"font-weight: 400;\">'connection_id, user_id'<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0FilterExpression: <\/span><span style=\"font-weight: 400;\">'#roomId = :roomId'<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0ExpressionAttributeNames: {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">'#roomId'<\/span><span style=\"font-weight: 400;\">: <\/span><span style=\"font-weight: 400;\">'room_id'<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0},<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0ExpressionAttributeValues: {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">':roomId'<\/span><span style=\"font-weight: 400;\">: room_id,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0};<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0connectionData = await ddb.scan(scanParam).promise();<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">catch<\/span><span style=\"font-weight: 400;\"> (e) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> { statusCode: <\/span><span style=\"font-weight: 400;\">500<\/span><span style=\"font-weight: 400;\">, body: e.stack };<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0}\r\n\u00a0let url = (ENDPOINT === \"\") ? event.requestContext.domainName + '\/' + \r\n event.requestContext.stage : ENDPOINT + \"\/\"+ environment.toLowerCase();\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">console.log(url);<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> apigwManagementApi = <\/span><span style=\"font-weight: 400;\">new<\/span><span style=\"font-weight: 400;\"> AWS.ApiGatewayManagementApi({<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0apiVersion: <\/span><span style=\"font-weight: 400;\">'2018-11-29'<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0endpoint: url<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0});\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/ for each connection send a message through apigwManagementApi <\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0const postCalls = connectionData.Items.map(async ({ connection_id }) =&gt; {\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">\u00a0<\/span><span style=\"font-weight: 400;\">try<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0messageBody.data = postData;<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0await apigwManagementApi.postToConnection({ ConnectionId: connection_id, Data: JSON.stringify(messageBody)}).promise();<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0console.log(<\/span><span style=\"font-weight: 400;\">\"posted\"<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">catch<\/span><span style=\"font-weight: 400;\"> (e) {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0console.error(e);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><i><span style=\"font-weight: 400;\">\/\/if the connection in a stale status, the connection will be closed, and the connection_id will be removed from the dynamoDB table<\/span><\/i>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">if<\/span><span style=\"font-weight: 400;\"> (e.statusCode === <\/span><span style=\"font-weight: 400;\">410<\/span><span style=\"font-weight: 400;\">) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0console.log(<\/span><span style=\"font-weight: 400;\">`<\/span><span style=\"font-weight: 400;\">Found stale connection, deleting ${connection_id}<\/span><span style=\"font-weight: 400;\">`<\/span><span style=\"font-weight: 400;\">);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">var<\/span><span style=\"font-weight: 400;\"> deleteParams = {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0TableName: table,<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Key: {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0connection_id: { S: connection_id }<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0};<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0await ddb.deleteItem(deleteParams, <\/span><span style=\"font-weight: 400;\">function<\/span><span style=\"font-weight: 400;\"> (err) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0callback(<\/span><span style=\"font-weight: 400;\">null<\/span><span style=\"font-weight: 400;\">, {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0statusCode: err ? <\/span><span style=\"font-weight: 400;\">500<\/span><span style=\"font-weight: 400;\"> : <\/span><span style=\"font-weight: 400;\">200<\/span><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0body: err ? <\/span><span style=\"font-weight: 400;\">\"Failed to disconnect: \"<\/span><span style=\"font-weight: 400;\"> + JSON.stringify(err) : <\/span><span style=\"font-weight: 400;\">\" Disconnected.\"<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0}).promise();<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0});<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">else<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> { statusCode: <\/span><span style=\"font-weight: 400;\">500<\/span><span style=\"font-weight: 400;\">, body: e.stack };<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0}<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0});<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">try<\/span><span style=\"font-weight: 400;\"> {<\/span>\r\n<span style=\"font-weight: 400;\"> \u00a0\u00a0\u00a0await Promise.all(postCalls);<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0} <\/span><span style=\"font-weight: 400;\">catch<\/span><span style=\"font-weight: 400;\"> (e) {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> { statusCode: <\/span><span style=\"font-weight: 400;\">500<\/span><span style=\"font-weight: 400;\">, body: e.stack };<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0\u00a0}\r\n<\/span><\/pre>\n<pre><span style=\"font-weight: 400;\">eturn<\/span><span style=\"font-weight: 400;\"> { statusCode: <\/span><span style=\"font-weight: 400;\">200<\/span><span style=\"font-weight: 400;\">, body: <\/span><span style=\"font-weight: 400;\">'Data sent.'<\/span><span style=\"font-weight: 400;\"> };<\/span>\r\n<span style=\"font-weight: 400;\">};<\/span><\/pre>\n<p><span style=\"font-weight: 400;\">Passiamo ora ad aggiungere le variabili d\u2019ambiente:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-815 aligncenter\" src=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-19-at-08.48.05.png\" alt=\"\" width=\"939\" height=\"184\" srcset=\"https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-19-at-08.48.05.png 939w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-19-at-08.48.05-400x78.png 400w, https:\/\/blog.besharp.it\/wp-content\/uploads\/2019\/07\/Screenshot-2019-06-19-at-08.48.05-768x150.png 768w\" sizes=\"(max-width: 939px) 100vw, 939px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">In questa funzione Lambda il codice \u00e8 in grado di distinguere le chiamate provenienti da SQS o quelle da API Gateway; sulla base di questa informazione, il corpo del messaggio e le informazioni relative all\u2019utente vengono ricostruite. Sulla base della <\/span><b>room_id<\/b><span style=\"font-weight: 400;\"> ricaviamo gli <\/span><b>user_id<\/b><span style=\"font-weight: 400;\"> e i <\/span><b>connection_id<\/b><span style=\"font-weight: 400;\"> dalla tabella delle connessioni di DynamoDB. Quindi procediamo a spedire il messaggio a tutti gli utenti cos\u00ec trovati.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Nel caso in cui ci sia un problema di connessione la Lambda provvede a cancellare la riga relativa sempre dalla tabella delle connessioni.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Una volta aggiunte tutte queste funzioni verifichiamo che i nomi utilizzati per descriverle siano coerenti con quelli indicati rispettivamente in <\/span><b>$connect<\/b><span style=\"font-weight: 400;\">, <\/span><b>$disconnect <\/b><span style=\"font-weight: 400;\">e <\/span><b>sendMessage<\/b><span style=\"font-weight: 400;\">. A passaggi ultimati l\u2019architettura del nostro sistema di notifiche \u00e8 completata, possiamo testarla direttamente immettendo un messaggio con questo esempio:<\/span><\/p>\n<pre><i><span style=\"font-weight: 400;\">sqs <\/span><\/i><span style=\"font-weight: 400;\">= <\/span><b><i>Aws<\/i><\/b><span style=\"font-weight: 400;\">::<\/span><b><i>SQS<\/i><\/b><span style=\"font-weight: 400;\">::<\/span><b><i>Client<\/i><\/b><span style=\"font-weight: 400;\">.new(<\/span><b>region<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">region<\/span><\/i><span style=\"font-weight: 400;\">)<\/span>\r\n<i><span style=\"font-weight: 400;\">payload <\/span><\/i><span style=\"font-weight: 400;\">= <\/span><b><i>JSON<\/i><\/b><span style=\"font-weight: 400;\">.generate(<\/span><b>user_id<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">user_id<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b>room_id<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">room_id<\/span><\/i><span style=\"font-weight: 400;\">, <\/span><b>data<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">message<\/span><\/i><span style=\"font-weight: 400;\">)<\/span>\r\n<i><span style=\"font-weight: 400;\">params <\/span><\/i><span style=\"font-weight: 400;\">= {<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0<\/span><b>message_body<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">payload<\/span><\/i><span style=\"font-weight: 400;\">,<\/span>\r\n<span style=\"font-weight: 400;\">\u00a0<\/span><b>queue_url<\/b><span style=\"font-weight: 400;\">: <\/span><i><span style=\"font-weight: 400;\">config<\/span><\/i><span style=\"font-weight: 400;\">.queue_url<\/span>\r\n<span style=\"font-weight: 400;\">}\r\n<\/span><\/pre>\n<pre>sqs.send_message(params)<\/pre>\n<p>Altrimenti lato client si pu\u00f2 utilizzare questo esempio:<\/p>\n<pre>function sendMessage(){ ws.send(JSON.stringify( {\u201caction\u201d: \u201csendMessage\u201d, \u201cdata\u201d : \u201cmessage\u201d } ); }<\/pre>\n<p>Con questo si conclude il nostro tutorial su come sviluppare un microservizio di gestione notifiche basato sui servizi AWS, completo di autenticazione tramite API Gateway, DynamoDB, SQS e Lambda.<\/p>\n<p>Uno degli aspetti pi\u00f9 interessanti della soluzione \u00e8 sicuramente la sua compattezza &#8211; tutta la logica \u00e8 implementata in sole quattro funzioni Lambda piuttosto semplici &#8211; mantenendo al contempo una certa versatilit\u00e0.<\/p>\n<p>Nel caso si voglia gestire il lifecycle dell\u2019infrastruttura secondo il paradigma dell\u2019Infrastructure-as-Code, ad esempio tramite un SAM template, un ultimo accorgimento potrebbe essere la creazione di un record ALIAS di Route53 per disaccoppiare l\u2019URL chiamato dal client da quello di API Gateway che, essendo generato in maniera programmatica, cambia ad ogni deploy.<\/p>\n<p>Vuoi saperne di pi\u00f9 su questa soluzione e su come <strong>beSharp pu\u00f2 aiutarti nello sviluppo di applicazioni Serverless e Cloud-native<\/strong> su AWS? <a href=\"https:\/\/www.besharp.it\/contact-us\/\">Contattaci!<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>La diffusione capillare del Cloud computing ha portato, negli ultimi anni, ad una adozione massiva del paradigma di sviluppo applicativo [&hellip;]<\/p>\n","protected":false},"author":6,"featured_media":787,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[477],"tags":[255,263,267],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.9.1 - 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