Azure – servizio di Cloud Computing di Microsoft
Tutte le soluzioni esposte da Azure [Link]
Introduction to Windows Azure Cloud Services
Cloud Services Tutorials [Link]
Scarica qui la presentazione che spiega cos’è il Cloud scaricata da Slideshare.net
Cloude Service = [Rol 1 x2, Role 2 x3, Role 3 x1, …]
Role Instance = VM + Guest OS + {service bits} + {x}
x1 = instance = one virtual machine
Tutorial [Link]
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Azure – Paas
PaaS is the self-service enabled compute service that provisions computing resources in terms of CPU, memory and volatile disk storage through resource descriptors provided at the deployment time. The unit of deployment in PaaS is an application package and its associated data. PaaS is characterized by the stateless compute nodes which will be complimented by a collection of managed services for accelerating the application delivery to the market. These managed services shown in the picture below are not unique to PaaS as the same can be consumed inside an IaaS hosted application.
Windows Azure PaaS is available to application developers as Web Role and Worker Role abstractions deployed into a resource container titled Cloud Service
· The Web Role presents ASP.NET programming model that is meant to be used as a template for spawning individual node instances of a web farm as dictated by the accompanying XML resource descriptor.
· The Worker Role exposes a background processing programming model for implementing batch processing farms with the necessary resources described in the accompanying XML resource descriptor.
The complete list of positive and negative aspects of PaaS are listed below:
1. Business: Low Total Cost of Ownership:
Automated server maintenance and auto scaling of compute resources for meeting temporal resource demands are the two significant contributors towards lowering the cost of operations
2. Business: Accelerates Innovation:
With IaaS, applications tend to be sticky to the underlying platform due to the tight coupling resulting from the complete control developers have on the OS and application platform stack. Migrating to newer releases of the infrastructure is much harder in IaaS resulting in applications getting stuck in the older platforms there by hampering innovation.
Technology: Better Development Operations
· Windows Azure PaaS is characterized by the REST interfaces for a fine grained interaction with the deployment artifacts
· Developers are no longer needed to work at the levels that require deep understanding of the OS and the networking infrastructure.
· PaaS makes all of this very simple by allowing a developer to add network endpoints with public and private port mapping through intuitive commands or UI
Technology: Mitigates Vulnerability Risks
Maintaining physical and/or virtual servers is a laborious process as it involves downloading of the patches, testing them on a representative sample of servers, verify application compatibility, distribute patches and perform rolling upgrades so as to not to impact the availability of the mission critical apps. In spite of the advances in automation, it still requires significant effort on the part of the IT Pros to keep the infrastructure healthy. Azure PaaS team takes care of the infrastructure health by keeping the infrastructure updated against all the known vulnerabilities for which fixes have been distributed. Since this process is opaque to the developers and is automatic, the risk of information breach resulting from the known vulnerabilities is significantly reduced
Platform as a Service
Il Platform as a Service (PaaS) rappresenta una tipologia di servizio fornito del tutto differente, anche se per molti versi simile all’IaaS. A essere fornito come servizio, questa volta, non c’è solo l’hardware, ma anche la piattaforma che astrae l’hardware stesso e permette di usufruire di un set di funzionalità che consentono di ottenere load balancing, storage, reti, Virtual Machine, deployment. Il vantaggio è quello di concentrarsi solo ed esclusivamente sullo sviluppo dell’applicazione, e non perdersi nell’analisi di problematiche legate all’ambiente in cui essa deve essere distribuita, ottenendo contestualmente dalla piattaforma la scalabilità e l’affidabilità necessaria. Come per l’IaaS, non dobbiamo preoccuparci di aggiornare il sistema operativo: viene tutto gestito dinamicamente e in modo del tutto automatico dalla piattaforma. Se in determinati periodi abbiamo carichi di picco, per esempio durante il periodo natalizio un negozio online può essere soggetto a un carico di richieste decisamente più alto, la piattaforma è in grado di adeguare la propria struttura per rispondere alle mutate esigenze, anche se temporanee. Diversamente da quanto viene fatto nelle soluzioni tradizionali, dove tutta l’infrastruttura hardware e software deve essere progettata per essere scalabile e affidabile, così da evitare problemi e interruzioni del servizio che causano ripercussioni sul business. Un’infrastruttura di Cloud Computing, invece, è progettata partendo dal presupposto che i problemi ci possono essere. È quindi in grado di risolverli autonomamente, per quanto possibile, attraverso meccanismi in grado di non bloccare il normale flusso applicativo, come la replica delle macchine virtuali.
Fonte [link]