Why is Cloud Service?

Nostalgic, remember this interface?

Yes, this is the first edition of Windows Azure Management Portal, developed with Silverlight, awesome!

Strange, why not virtual machine?

Yes, there are no virtual machines in the original Windows Azure!

You see the hosted service? This is the predecessor of cloud service. Windows Azure was originally started from the PAAs, it is not difficult to understand-Microsoft's operating system, development tools are industry-leading, the traditional operating system and development tools "cloud", leveraging the original customer base and market influence, will undoubtedly become a major advantage of Windows Azure.

The Hosted service consists of two roles:

• Web role:web Application (Asp.net,php,java ...)
• Worker ROLE:WCF Service (Web service,restful service)

Either web Role or worker Role, host is on the virtual machine, and it is a virtual machine running Windows Server. Just because these virtual machines are managed centrally by Windows Azure, users don't need to pay attention to them, or the virtual machines are packaged by Windows Azure. Users create and publish hosted Service through Visual Studio. A hosted service can have multiple instance, each instance corresponding to a virtual machine. In short, for the user, the virtual machine is not fully aware of the existence. A very complete and elegant PAAs experience!

Later, the Hosted service appeared a new ROLE:VM role--this can be regarded as the predecessor of virtual machine. With VM role, users can deploy applications freely on virtual machines or more flexibly customize and tune Web role and worker role.

It is said that Windows Azure added VM Role in the hosted service because of the follow-up to AWS EC2. Apparently back in the 45, most users understand and accept virtual machines (IaaS) much more than managed services (PaaS). The idea is too advanced, inevitably high place is cold.

Later, VM role became a standalone virtual machine, and with support for the Linux operating system, users could finally deploy and use the Linux operating system on Windows Azure. In fact, Hyper-V originally supported the Linux operating system as the guest OS, but at the time, Linux was also considered "cancer" by Microsoft.

Although VM role was eventually finalized-becoming a standalone virtual machine, it was still unable to get rid of the hosted Service. After all, this is a key and the core of the underlying architecture design, not so easily changed or eliminated. Hosted Service also evolved into today's cloud service. Although cloud service is becoming more and more powerful, it originates from the hosted service. and the concept of Web Role,worker Role is gradually being watered down.

Now that you know the "cause and effect", let's summarize our knowledge of cloud service:

• A Cloud service is a container that can include managed services or virtual machines.
• Hosted services deployed in cloud service support open source technologies such as Java,php,python, Ruby, and node. js, but the virtual machines used to host the service are running the Windows Server operating system. The instance of a managed service is a virtual machine running the Windows Server operating system, and a managed service can contain multiple instance.
• A virtual machine must be placed in a cloud service. A cloud service can contain multiple virtual machines, but one VM can only belong to one cloud service.
• A cloud service is assigned a VIP by default, namely: Dynamically assigned public IP address.
• A cloud service is assigned a unique two-level domain name by default. The Chinese version is: xxx.chinacloudapp.cn; international edition is: Xxx.cloudapp.net.
• Virtual machines in the same cloud service are connected to the public via NAT, i.e., in the default configuration, multiple virtual machines share the same VIP.
• The virtual machine implements port mappings through endpoints (endpoint), for example, by mapping the 22 port on the intranet to 2222 of the public network.
• Multiple virtual machines in the same cloud service cannot open the same port (endpoint/endpoint) to the public network, for example: Server A opens 80 ports to the public network, and server A is in the same cloud The virtual machine in the service can no longer open 80 ports to the public network.
• Each cloud service can be configured with one or more load balancing endpoints (endpoint), and virtual machines in the cloud service can be serviced externally (to the public network) through a load balancing endpoint.

Why is Cloud Service?