Google Cloud Platform

Google Cloud
sito web
Logo
Logo
URLcloud.google.com
Tipo di sitoWeb service, Cloud computing
RegistrazioneObbligatoria
ProprietarioGoogle
Lancio7 aprile 2008
Scritto inJava, C++, Python, Go, Ruby

Google Cloud (a volte noto come GCP, precedentemente noto come Google Cloud Platform), offerto da Google, è una suite di servizi modulari di cloud computing tra cui archiviazione dati, analisi dei dati e apprendimento automatico, oltre ad una serie di strumenti di gestione. Funziona sulla stessa infrastruttura che Google utilizza internamente per i suoi prodotti per gli utenti finali, come ad esempio Ricerca Google, Gmail, e Google Documenti. La registrazione richiede un carta di credito o dettagli del conto bancario.

Google Cloud offre Infrastructure as a service, Platform as a service ed ambienti serverless.

Nell'aprile 2008, Google ha annunciato App Engine, una piattaforma per lo sviluppo e l'hosting di applicazioni web nei data center gestiti da Google, il primo servizio di cloud computing dell'azienda. Il servizio è diventato generalmente disponibile nel novembre 2011. Dall'annuncio di App Engine, Google ha aggiunto ulteriori servizi cloud alla piattaforma.

Google Cloud Platform è una parte di Google Cloud, che include l'infrastruttura cloud pubblica di Google Cloud, nonché Google Workspace (G Suite), versioni aziendali di Android e ChromeOS e interfacce di programmazione delle applicazioni (API) per il machine learning e le aziende di servizi di mappatura.

Prodotti

Conferenza di presentazione di Google Container Engine/Kubernetes

Google offre oltre 100 prodotti con il marchio Google Cloud. Alcuni dei servizi chiave sono elencati di seguito.

Computazione

Archiviazione e database

Rete

Big data

AI cloud

Strumenti di gestione

Identità e sicurezza

Internet delle cose (IoT)

Piattaforma API

Regioni e zone

Una regione è una posizione geografica specifica in cui gli utenti possono distribuire risorse cloud. Ogni regione è un'area geografica indipendente che, a sua volta, è divisa in zone.

Una zona è un'area di distribuzione per le risorse Google Cloud all'interno di una regione. In caso di guasi, le zone dovrebbero essere considerate un singolo dominio all'interno di una regione. La maggior parte delle regioni dispone di tre o più zone.

A partire dal terzo trimestre 2023, Google Cloud è disponibile in 39 regioni e 118 zone. Questo è l'elenco:

Nome regione Periodo di lancio Località Zone
us-west1 Q3, 2016 The Dalles, Oregon, USA
  • us-west1-a
  • us-west1-b
  • us-west1-c
us-west2 Q3, 2018 Los Angeles, California, USA
  • us-west2-a
  • us-west2-b
  • us-west2-c
us-west3 Q1, 2020 Salt Lake City, Utah, USA
  • us-west3-a
  • us-west3-b
  • us-west3-c
us-west4 Q2, 2020 Las VegasNevada, USA
  • us-west4-a
  • us-west4-b
  • us-west4-c
us-central1 Council Bluffs, Iowa, USA
  • us-central1-a
  • us-central1-b
  • us-central1-c
  • us-central1-f
us-east1 Q4, 2015 Moncks Corner, South Carolina, USA
  • us-east1-b
  • us-east1-c
  • us-east1-d
us-east4 Q2, 2017 Ashburn, Virginia, USA
  • us-east4-a
  • us-east4-b
  • us-east4-c
us-east5 Q2, 2022 Columbus, Ohio, USA
  • us-east5-a
  • us-east5-b
  • us-east5-c
us-south1 Q2, 2022 Dallas, Texas,
  • us-south1-a
  • us-south1-b
  • us-south1-c
northamerica-northeast1 Q1, 2018 Montréal, Canada
  • northamerica-northeast1-a
  • northamerica-northeast1-b
  • northamerica-northeast1-c
northamerica-northeast2 Q3, 2021 Toronto, Canada
  • northamerica-northeast2-a
  • northamerica-northeast2-b
  • northamerica-northeast2-c
southamerica-east1 Q3, 2017 São Paulo, Brasile
  • southamerica-east1-a
  • southamerica-east1-b
  • southamerica-east1-c
southamerica-west1 Q3, 2021 Santiago, Cile
  • southamerica-west1-a
  • southamerica-west1-b
  • southamerica-west1-c
europe-west1 St. Ghislain, Belgio
  • europe-west1-b
  • europe-west1-c
  • europe-west1-d
europe-west2 Q2, 2017 Londra, Regno Unito
  • europe-west2-a
  • europe-west2-b
  • europe-west2-c
europe-west3 Q3, 2017 Francoforte, Germania
  • europe-west3-a
  • europe-west3-b
  • europe-west3-c
europe-west4 Q1, 2018 Eemshaven, Paesi Bassi
  • europe-west4-a
  • europe-west4-b
  • europe-west4-c
europe-west6 Q1, 2019 Zurigo, Svizzera
  • europe-west6-a
  • europe-west6-b
  • europe-west6-c
europe-west8 Q2, 2022 Milano, Italia
  • europe-west8-a
  • europe-west8-b
  • europe-west8-c
europe-west9 Q2, 2022 Parigi,

Francia

  • europe-west9-a
  • europe-west9-b
  • europe-west9-c
europe-west10 Q3, 2023 Berlino, Germania
  • europe-west10-a
  • europe-west10-b
  • europe-west10-c
europe-west12 Q1, 2023 Torino, Italia
  • europe-west12-a
  • europe-west12-b
  • europe-west12-c
europe-central2 Q2, 2021 Varsavia, Polonia
  • europe-central2-a
  • europe-central2-b
  • europe-central2-c
europe-north1 Q2, 2018 Hamina, Finlandia
  • europe-north1-a
  • europe-north1-b
  • europe-north1-c
europe-southwest1 Q2, 2022 Madrid, Spagna
  • europe-southwest1-a
  • europe-southwest1-b
  • europe-southwest1-c
me-west1 Q4, 2022 Tel Aviv, Israele
  • me-west1-a
  • me-west1-b
  • me-west1-c
me-central1 Q2, 2023 Doha, Qatar
  • me-central1-a
  • me-central1-b
  • me-central1-c
asia-south1 Q4, 2017 Mumbai, India
  • asia-south1-a
  • asia-south1-b
  • asia-south1-c
asia-south2 Q2, 2021 Delhi, India
  • asia-south2-a
  • asia-south2-b
  • asia-south2-c
asia-southeast1 Q2, 2017 Jurong West, Singapore
  • asia-southeast1-a
  • asia-southeast1-b
  • asia-southeast1-c
asia-southeast2 Q2, 2020 Jakarta, Indonesia
  • asia-southeast2-a
  • asia-southeast2-b
  • asia-southeast2-c
asia-east2 Q3, 2018 Hong Kong
  • asia-east2-a
  • asia-east2-b
  • asia-east2-c
asia-east1 Changhua County, Taiwan
  • asia-east1-a
  • asia-east1-b
  • asia-east1-c
asia-northeast1 Q4, 2016 Tokyo, Giappone
  • asia-northeast1-a
  • asia-northeast1-b
  • asia-northeast1-c
asia-northeast2 Q2, 2019 Osaka, Giappone
  • asia-northeast2-a
  • asia-northeast2-b
  • asia-northeast2-c
asia-northeast3 Q1, 2020 Seul, Korea
  • asia-northeast3-a
  • asia-northeast3-b
  • asia-northeast3-c
australia-southeast1 Q3, 2017 Sydney, Australia
  • australia-southeast1-a
  • australia-southeast1-b
  • australia-southeast1-c
australia-southeast2 Q2, 2021 Melbourne, Australia
  • australia-southeast2-a
  • australia-southeast2-b
  • australia-southeast2-c

Confronto con altri fornitori di servizi cloud

Google Cloud Servizi Web di Amazon Microsoft Azure Oracle Cloud
Google Computing Engine Amazon EC2 Macchine virtuali di Azure Oracle Cloud Infra OCI
Google App Engine AWS Elastic Beanstalk Servizi di applicazioni di Azure Container di applicazioni Oracle
Motore Kubernetes di Google Servizio di Kubernetes Elastic Amazon Servizio di Azure Kubernetes Servizio Kubernetes Oracle
Google Cloud Bigtable Amazon DynamoDB Azure Cosmos DB Database Oracle NoSQL
Google BigQuery Amazon Redshift Azure Synapse Analytics Oracle Data Warehouse Autonomo
Google Cloud funzioni AWS Lambda Funzioni di Azure Oracle Cloud Fn
Google Cloud Data Store Amazon DynamoDB Azure Cosmos DB Database Oracle NoSQL
Google Cloud Storage Amazon S3 Storage di Blob di Azure Oracle Cloud Storage OCI

Cronistoria

Clienti di rilievo

I clienti annunciati nel 2023 includono: Kingfisher, Il governo del Kuwait, Deutsche Börse Group, Unity, Uber, FanCode e Mercedes-Benz.

Note

  1. ↑ cloud.google.com, https://cloud.google.com/products/. URL consultato il 2 giugno 2017.
  2. ↑ Abhishek Verma, Luis Pedrosa e Madhukar Korupolu, Large-scale cluster management at Google with Borg, in EuroSys '15: Proceedings of the Tenth European Conference on Computer Systems, 17 aprile 2015, DOI:10.1145/2741948.2741964. URL consultato il 5 ottobre 2023.
  3. ↑ Google Cloud, https://cloud.google.com/free/docs/gcp-free-tier.
  4. ↑ (EN) http://fortune.com/2016/09/29/ggoogle-cloud-branding-g-suite/.
  5. 1 2 Google Cloud Blog, https://cloud.google.com/blog/topics/hybrid-cloud/new-platform-for-managing-applications-in-todays-multi-cloud-world/.
  6. ↑ Google Cloud, https://cloud.google.com/gke-on-prem/.
  7. ↑ Knative, https://knative.dev/.
  8. 1 2 Google Cloud, https://cloud.google.com/run/.
  9. ↑ [Google Cloud], https://cloud.google.com/anthos/docs/concepts/overview. URL consultato il 5 gennaio 2021.
  10. ↑ (EN) Fortune, https://fortune.com/2015/05/06/google-launches-bigtable-database/. URL consultato il 28 aprile 2022.
  11. ↑ (EN) Business Insider, https://www.businessinsider.com/google-launches-cloud-spanner-2017-2. URL consultato il 28 aprile 2022.
  12. ↑ (EN) Ars Technica, https://arstechnica.com/information-technology/2013/05/google-wants-your-wordpress-blog-and-everything-else-in-its-cloud/. URL consultato il 28 aprile 2022.
  13. ↑ (EN) TechCrunch, https://social.techcrunch.com/2014/06/16/google-cloud-platform-gets-ssd-persistent-disks-and-http-load-balancing/[collegamento interrotto]. URL consultato il 28 aprile 2022.
  14. ↑ (EN) ZDNet, https://www.zdnet.com/article/google-rolls-out-memorystore-for-memcached-in-beta/. URL consultato il 28 aprile 2022.
  15. ↑ (EN) Network World, https://www.networkworld.com/article/3284930/google-cloud-storage-gets-a-boost-with-managed-nas-service.html. URL consultato il 28 aprile 2022.
  16. ↑ (EN) TechCrunch, https://social.techcrunch.com/2022/05/11/google-cloud-launches-alloydb-a-new-fully-managed-postgresql-database-service/[collegamento interrotto]. URL consultato il 12 maggio 2022.
  17. ↑ (EN) ZDNet, https://web.archive.org/web/20220427024109/https://www.zdnet.com/pictures/google-bigquery-self-service-cloud-data-analysis-from-your-ipad-or-desktop/. URL consultato il 27 aprile 2022 (archiviato dall'url originale il 27 aprile 2022).
  18. ↑ (EN) TechCrunch, https://social.techcrunch.com/2015/04/16/google-opens-cloud-dataflow-to-all-developers-launches-european-zone-for-bigquery/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  19. ↑ (EN) Google Cloud, https://cloud.google.com/data-fusion. URL consultato il 21 dicembre 2022.
  20. ↑ (EN) TechCrunch, https://social.techcrunch.com/2015/09/23/google-launches-cloud-dataproc-a-managed-spark-and-hadoop-big-data-service/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  21. ↑ (EN) TechCrunch, https://social.techcrunch.com/2018/05/01/google-launches-cloud-composer-a-new-workflow-automation-tool-for-developers/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  22. ↑ (EN) TechCrunch, https://social.techcrunch.com/2015/10/13/google-launches-cloud-datalab-an-interactive-tool-for-exploring-and-visualizing-data/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  23. ↑ (EN) VentureBeat, https://web.archive.org/web/20220707114924/https://venturebeat.com/2017/03/09/google-launches-cloud-dataprep-an-embedded-version-of-trifacta/. URL consultato il 27 aprile 2022 (archiviato dall'url originale il 7 luglio 2022).
  24. ↑ (EN) TechCrunch, https://social.techcrunch.com/2015/03/04/googles-cloud-pubsub-real-time-messaging-service-is-now-in-public-beta/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  25. ↑ (EN) Computerworld, https://www.computerworld.com/article/3075749/google-goes-after-microsoft-tableau-and-others-with-a-free-analytics-tool.html. URL consultato il 27 aprile 2022.
  26. ↑ InfoWorld, https://www.infoworld.com/article/3637001/google-cloud-tools-aim-to-ease-machine-learning-cross-cloud-analytics.html.
  27. ↑ Copia archiviata, su Protocol. URL consultato il 20 ottobre 2023 (archiviato dall'url originale il 16 maggio 2023).
  28. ↑ (EN) CNBC, https://www.cnbc.com/2018/01/17/google-launches-cloud-automl.html. URL consultato il 27 aprile 2022.
  29. ↑ (EN) Forbes, https://www.forbes.com/sites/moorinsights/2016/05/26/googles-tpu-chip-creates-more-questions-than-answers/. URL consultato il 27 aprile 2022.
  30. ↑ (EN) TechCrunch, https://social.techcrunch.com/2016/03/23/google-launches-new-machine-learning-platform/[collegamento interrotto]. URL consultato il 27 aprile 2022.
  31. ↑ (EN) VentureBeat, https://web.archive.org/web/20220427062342/https://venturebeat.com/2018/08/16/2384861/. URL consultato il 27 aprile 2022 (archiviato dall'url originale il 27 aprile 2022).
  32. ↑ (EN) TechRepublic, https://www.techrepublic.com/article/google-officially-unveils-chatbot-dialogflow-enterprise/. URL consultato il 27 aprile 2022.
  33. ↑ (EN) InfoQ, https://www.infoq.com/news/2016/08/google-nlpaas/. URL consultato il 27 aprile 2022.
  34. ↑ (EN) 9to5Google, https://9to5google.com/2016/07/20/google-natural-language-speech-api-beta/. URL consultato il 27 aprile 2022.
  35. ↑ (EN) The Verge, https://www.theverge.com/2018/3/27/17167200/google-ai-speech-tts-cloud-deepmind-wavenet. URL consultato il 27 aprile 2022.
  36. ↑ Futurism, https://futurism.com/launch-google-cloud-vision-revolutionizes-machines-see. URL consultato il 27 aprile 2022.
  37. ↑ (EN) The Indian Express, https://indianexpress.com/article/technology/tech-news-technology/google-next-2017-video-intelligence-api-can-recognise-objects-in-a-video/. URL consultato il 27 aprile 2022.
  38. ↑ (EN) TechTarget, https://www.techtarget.com/searchcloudcomputing/definition/Google-Stackdriver. URL consultato il 27 aprile 2022.
  39. ↑ (EN) Jose Ugia Gonzalez e S. P. T. Krishnan, Building Your Next Big Thing with Google Cloud: A Guide for Developers and Enterprise Architects, Apress, 15 giugno 2015, ISBN 978-1-4842-1004-8.
  40. ↑ cloud.google.com, https://cloud.google.com/free/docs/map-aws-google-cloud-platform. URL consultato il 14 aprile 2017.
  41. ↑ cloud.google.com, https://cloud.google.com/free/docs/map-azure-google-cloud-platform. URL consultato il 14 aprile 2017.
  42. ↑ cloud.oracle.com, https://web.archive.org/web/20191113122528/https://cloud.oracle.com/en_US/iaas/cloud-service-mapping. URL consultato il 13 giugno 2019 (archiviato dall'url originale il 13 novembre 2019).
  43. ↑ Google App Engine Blog, http://googleappengine.blogspot.com/2008/04/introducing-google-app-engine-our-new.html. URL consultato l'8 settembre 2018.
  44. ↑ Google Storage for Developers, http://googlecode.blogspot.com/2010/05/google-storage-for-developers-preview.html. URL consultato l'8 settembre 2018.
  45. 1 2 Google Cloud SQL, http://googlecode.blogspot.com/2011/10/google-cloud-sql-your-database-in-cloud.html. URL consultato l'8 settembre 2018.
  46. ↑ (EN) https://cloudplatform.googleblog.com/2012/06/google-compute-engine-launches.html.
  47. ↑ (EN) https://cloudplatform.googleblog.com/2013/12/google-compute-engine-is-now-generally-available.html.
  48. ↑ (EN) https://techcrunch.com/2013/08/15/google-cloud-storage-now-features-server-side-encryption/.
  49. ↑ (EN) https://cloudplatform.googleblog.com/2014/02/google-cloud-sql-now-generally-available.html.
  50. ↑ (EN) https://techcrunch.com/2014/05/07/google-acquires-cloud-monitoring-service-stackdriver/.
  51. ↑ (EN) https://cloudplatform.googleblog.com/2014/06/an-update-on-container-support-on-google-cloud-platform.html.
  52. ↑ (EN) https://cloudplatform.googleblog.com/2014/06/sneak-peek-google-cloud-dataflow-a-cloud-native-data-processing-service.html.
  53. ↑ (EN) https://techcrunch.com/2014/10/21/google-acquires-firebase-to-help-developers-build-better-realtime-apps/.
  54. ↑ (EN) https://cloudplatform.googleblog.com/2014/11/unleashing-containers-and-kubernetes-with-google-compute-engine.html.
  55. ↑ https://www.datacenterknowledge.com/archives/2015/01/14/googles-stackdriver-based-cloud-monitoring-now-in-beta.
  56. ↑ (EN) https://techcrunch.com/2015/03/04/googles-cloud-pubsub-real-time-messaging-service-is-now-in-public-beta.
  57. ↑ (EN) https://www.theregister.co.uk/2015/04/13/google_cloud_networking/.
  58. ↑ (EN) https://techcrunch.com/2015/04/16/google-opens-cloud-dataflow-to-all-developers-launches-european-zone-for-bigquery/.
  59. ↑ (EN) https://cloudplatform.googleblog.com/2015/08/Google-Container-Engine-is-Generally-Available.html.
  60. ↑ (EN) Copia archiviata. URL consultato il 20 ottobre 2023 (archiviato dall'url originale il 26 maggio 2022).
  61. ↑ (EN) https://www.forbes.com/sites/janakirammsv/2016/02/09/google-brings-serverless-computing-to-its-cloud-platform/#6204e4de1186.
  62. ↑ (EN) https://techcrunch.com/2016/09/08/google-will-acquire-apigee-for-625-million/.
  63. ↑ Copia archiviata. URL consultato il 20 ottobre 2023 (archiviato dall'url originale il 30 novembre 2018).
  64. ↑ (EN) https://techcrunch.com/2016/11/21/google-acquires-qwiklabs-to-teach-developers-cloud-skills/.
  65. ↑ (EN) https://cloudplatform.googleblog.com/2017/02/introducing-Cloud-Spanner-a-global-database-service-for-mission-critical-applications.html.
  66. ↑ (EN) https://cloudplatform.googleblog.com/2017/03/welcome-Kaggle-to-Google-Cloud.html.
  67. ↑ (EN) https://cloudplatform.googleblog.com/2017/04/220000-cores-and-counting-MIT-math-professor-breaks-record-for-largest-ever-Compute-Engine-job.html.
  68. ↑ (EN) https://cloudplatform.googleblog.com/2017/05/introducing-Google-Cloud-IoT-Core-for-securely-connecting-and-managing-IoT-devices-at-scale.html.
  69. ↑ (EN) https://cloudplatform.googleblog.com/2017/11/introducing-Certified-Kubernetes-and-Google-Kubernetes-Engine.html.
  70. ↑ (EN) https://cloudplatform.googleblog.com/2018/02/the-thing-is-Cloud-IoT-Core-is-now-generally-available.html.
  71. ↑ (EN) https://techcrunch.com/2018/02/15/google-to-acquire-xively-iot-platform-from-logmein/.
  72. ↑ (EN) https://www.zdnet.com/article/google-releases-cloud-tpu-beta-gpu-support-for-kubernetes/.
  73. ↑ Copia archiviata, su gartner.com. URL consultato l'8 settembre 2018 (archiviato dall'url originale il 30 novembre 2018).
  74. ↑ (EN) https://cloudplatform.googleblog.com/2018/05/Introducing-Cloud-Memorystore-A-fully-managed-in-memory-data-store-service-for-Redis.html.
  75. ↑ Google Cloud Blog, https://cloud.google.com/blog/products/serverless/announcing-cloud-run-the-newest-member-of-our-serverless-compute-stack/.
  76. ↑ Forbes, https://www.forbes.com/sites/janakirammsv/2019/04/14/everything-you-want-to-know-about-anthos-googles-hybrid-and-multi-cloud-platform/.
  77. ↑ Google Cloud Blog, https://cloud.google.com/blog/products/serverless/knative-based-cloud-run-services-are-ga/.
  78. ↑ businessinsider.com, https://www.businessinsider.com/google-cloud-next-postponed-digital-conference-coronavirus-2020-3. URL consultato il 17 marzo 2020.
  79. ↑ https://dlt.withgoogle.com/eos/.
  80. ↑ https://www.forbes.com/sites/tatianakoffman/2020/10/06/google-cloud-joins-forces-with-eos/.
  81. ↑ wikieduonline.com, https://www.wikieduonline.com/wiki/Google_Cloud_Platform_timeline.
  82. ↑ Google Cloud Blog, https://cloud.google.com/blog/products/containers-kubernetes/introducing-gke-autopilot.
  83. ↑ (EN) IT Business Edge (ITBE), https://www.itbusinessedge.com/development/google-makes-case-for-managing-ai-models/. URL consultato il 13 gennaio 2023.
  84. ↑ (EN) TelecomTV, https://www.telecomtv.com/content/edge/mobiledgex-acquired-by-google-cloud-44315/. URL consultato il 29 aprile 2022.
  85. ↑ blog.google, https://blog.google/technology/ai/ai-developers-google-cloud-workspace/.
  86. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2022-11-30-Kingfisher-Chooses-Google-Cloud-as-Catalyst-for-Growth-and-Innovation. URL consultato il 21 aprile 2023.
  87. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-01-05-The-Government-of-Kuwait-Selects-Google-Cloud-to-Commence-Nationwide-Digital-Transformation-Roadmap. URL consultato il 21 aprile 2023.
  88. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-02-09-Deutsche-Borse-Group-and-Google-Cloud-Announce-Strategic-Partnership-to-Accelerate-Innovation. URL consultato il 21 aprile 2023.
  89. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-01-26-Unity-and-Google-Deepen-Collaboration-to-Accelerate-Game-Developer-Success. URL consultato il 21 aprile 2023.
  90. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-02-13-Google-and-Uber-Deepen-Partnership-to-Reimagine-the-Customer-Experience. URL consultato il 21 aprile 2023.
  91. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-02-23-FanCode-and-Google-Cloud-Collaborate-to-Transform-the-Live-Sports-Viewing-Experience-for-Users-Across-South-Asia. URL consultato il 21 aprile 2023.
  92. ↑ (EN) Google Cloud Press Corner, https://www.googlecloudpresscorner.com/2023-02-22-Mercedes-Benz-and-Google-Join-Forces-to-Create-Next-Generation-Navigation-Experience. URL consultato il 21 aprile 2023.

Voci correlate

Altri progetti

Collegamenti esterni