JugTAAS ReSTful
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This document describes how to build a RESTful cloud service using OpenShift and related technologies like Tomcat, Jersey, JSON, and AngularJS. It discusses OpenShift as a hosting platform, the Richardson Maturity Model for REST APIs, best practices for REST including use of HTTP verbs, resources and hypermedia. Code examples demonstrate implementation including configuration of Tomcat in OpenShift, versioning via Git, and backports from another framework to support resources and hypermedia.
![POST /events/3 HTTP/1.1
{“request”: “options”}
HTTP/1.1 200 OK
{“options”: [
{“id”: 123, “date”: “2015-03-19”, “hour”: “18:00”},
{“id”: 124, “date”: “2015-03-19”, “hour”: “19:00”}
]}
POST /options/123 HTTP/1.1
{“request”: “confirm”, “participant”: “Tiziano”}
HTTP/1.1 200 OK
{“id”: 123, “participant”: “Tiziano”, “status”: “confirmed”}](https://image.slidesharecdn.com/jugtaasrestful-150320025254-conversion-gate01/85/JugTAAS-ReSTful-9-320.jpg)
JugTAAS ReSTful
- 1. JUGTAAS - RESTFUL OVVERO, COME SCOMODARE UN CLOUD RESTFUL PER UN LAVORO DA PAGINETTA PHP… byTiziano Lattisi
- 2. RICETTA • Servizio in cloud di RedHat (OpenShift) • Versionamento (git su GitHub e OpenShift) • Tomcat • Jax-ws (Jersey) • Json (Jackson) • AngularJS
- 3. OPENSHIFT DI REDHAT • Gratuito fino a tre applicazioni con tre "small gears" ciascuna • Repository git • SSH • https://www.openshift.com
- 4. RICHARDSON MATURITY MODEL • RMM estende l’approccio REST introducendo : • Risorse • Verbi HTTP • Hypermedia link
- 5. REST (RICAPITOLIAMO) • separazione client / server • stateless: nessun contesto client memorizzato sul server (Representational StateTransfer) • cacheable: i client possono fare cache delle risposte • layered: posso metterci in mezzo load balancing, cache, etc • code on demand (opzionale): es. il server può passare codice js • uniform interface: identificazione risorse, manipolazione attraverso la rappresentazione, messaggi auto-descrittivi, hateoas
- 6. HTTP COMETRASPORTO • HTTP semplicemente come tunnel • Nessun altro meccanismo tipico del web • URI rappresentano servizi (come soap, xml-rpc) • Architetture SOA (services oriented architecture)
- 7. POST /eventsService HTTP/1.1 {“request”: “get”, ”event-id”: 3} HTTP/1.1 200 OK {“title”: “...”, “description”: “...”, “status”: “pending”} POST /eventsService HTTP/1.1 {“request”: “confirm”, ”event-id”: 3} HTTP/1.1 200 OK {“title”: “...”, “description”: “...”, “status”: “confirmed”}
- 8. RISORSE • URI rappresentano risorse • I “metodi” vengono chiamati sulle risorse • Architettura ROA (resources oriented architecture)
- 9. POST /events/3 HTTP/1.1 {“request”: “options”} HTTP/1.1 200 OK {“options”: [ {“id”: 123, “date”: “2015-03-19”, “hour”: “18:00”}, {“id”: 124, “date”: “2015-03-19”, “hour”: “19:00”} ]} POST /options/123 HTTP/1.1 {“request”: “confirm”, “participant”: “Tiziano”} HTTP/1.1 200 OK {“id”: 123, “participant”: “Tiziano”, “status”: “confirmed”}
- 10. HTTPVERBS • I verbi HTTP per il controllo del ciclo di vita della risorsa (CRUD) • Utilizzo dei codici di risposta HTTP • Rispetto dei comportamenti safe e idempotent dei verbi HTTP
- 11. • Safe: la chiamata non comporta modificazioni sul server • Idempotent: chiamate successive alla prima non comportano modificazioni sul server (almeno per quanto il client possa percepire)
- 12. SAFE AND IDEMPOTENT safe idempotent verb ex. codes Select v v GET 200 OK Insert x x POST 201 Created Update/Insert x v PUT 204 No content Partial update x x PATCH 204 No content Delete x v DELETE 200 OK Client errors: 4xx (400 Bad request, 401 Unauthorized, 404 Not found,…) Server errors: 5xx
- 13. GET /events/3 HTTP/1.1 HTTP/1.1 200 OK {“id”: 3, “title”: “...”, “description”: “...”, “status”: “confirmed”} POST /events HTTP/1.1 {“title”: “...”, “description”: “...”} HTTP/1.1 201 CREATED {“id”: 4, “title”: “...”, “description”: “...”, “status”: “pending”}
- 14. HYPERMEDIA CONTROLS • HATEOAS (hypermedia as the engine of application state) • La risorsa espone dei link che indicano come proseguire nell’interazione con la risorsa stessa
- 15. GET /events?filterBy=confirmed&startIndex=4&size=4 HTTP/1.1 HTTP/1.1 200 OK { “events”: { “0”: “/services/events/1”, “1”: “/services/events/12” }, "_links": { “self”: “/events?filterBy=confirmed&startIndex=4&size=4”, “prev”: “/events?filterBy=confirmed&startIndex=0&size=4”, “next”: “/events?filterBy=confirmed&startIndex=8&size=4”, } }
- 16. GET /events/1 HTTP/1.1 HTTP/1.1 200 OK { “title”: “A new talk”, “description”: “An interesting talk” “events”: { “0”: “/services/events/1”, “1”: “/services/events/12” }, "_links": { “self”: “/events/1”, “confirm”: “/events/1/confirm”, “post-resource”: “/resources/1”, } }
- 17. FLUSSO GIT master develop v. 1.0 v. 2.0 master v. 1.0 v. 2.0 GITHUB OpenShift build & deploy handle
- 18. VEDIAMO UN PO’ DI COSE • API: services-jugtaas.rhcloud.com/docs/swagger-ui/?url=../api/services.json • ConfigurazioneTomcat OpenShift da git: • https://github.com/jugtaas/services/blob/develop/.openshift/config/server.xml • https://github.com/jugtaas/services/blob/develop/src/main/webapp/WEB-INF/web.xml • Backports ZoeXF: • https://github.com/jugtaas/services/blob/develop/src/main/java/org/jugtaas/services/ zoefxports/rest/AbstractResource.java • https://github.com/jugtaas/services/blob/develop/src/main/java/org/jugtaas/services/ zoefxports/db/Manager.java
- 19. NOTE • Abbiamo usato json, che non ha hypermedia support (json-ld oppure hal); non abbiamo usato xhtml/atom per AngularJs • PUT (idempotent) o POST (!idempotent)? • Risorse composite (buona idea per la cache): /events/3/speakers • Autenticazione/autorizzazione su ogni richiesta • Backport da ZoeFX per manager jpa e hateoas
- 20. RISORSE • Roy Fielding (tesi di dottorato, idea originale di REST): http:// www.ics.uci.edu/%7Efielding/pubs/dissertation/rest_arch_style.htm • Martin Fowler (articolo RMM): http://martinfowler.com/articles/ richardsonMaturityModel.html • http://www.w3.org/TR/json-ld/ • http://stateless.co/hal_specification.html • https://github.com/jugtaas/services
- 21. E ora passiamo al client…