[Reprinted] Flat qingcloud: Windows azure (2)

Now let's talk about storage service and fabric ).

Storage Service)

Windows Azure is an applicationProgramProvides several forms of data storage, as shown in:

 

The simplest data storage is blobs, which is a hierarchical data storage ., A data storage account contains one or more containers. Each container contains one or more blobs. A blog is used to store data in binary format and has a large capacity, they can also be associated with metadata, such as JPEG image shooting information and MP3 file singer information. Blobs is used for xdrives, a tool for viewing data on a local disk.

 

However, blobs cannot be used in all storage scenarios. Windows azure provides another method for applications: tables, but it is not a table in a relational database. In fact, tables store a group of entities that contain attributes (more like object databases ). Applications can directly use ADO. NET data services, instead of SQL. the reason why objects can be accessed directly is that tables allows scale-out storage to store data on several servers, which is far more efficient than relational databases. In practice, a table can store hundreds of millions of objects.

Blobs and tables are both applied to data access. The third storage mechanism provided by Windows Azure, queues, is different. It is used for asynchronous communication between a web role instance and a worker role instance. For example, when a request is sent to the Web role instance, the Web role will write a message in the queue to describe how to do it. A worker role instance waiting for a message reads the message and performs operations. The execution result is returned to another queue or processed in other ways.

Blobs, tables, and queues, all data is stored in three copies in Windows Azure, but we do not need to care about the specific implementation. These copies can contain errors, so the loss of a copy won't cause a disaster. Windows azure automatically backs up all data. Once the primary data is lost, the backup becomes available.

Windows azure storage data can be accessed by Windows azure applications, hosted applications, and other cloud platform applications under authorization. All three types of data can be authenticated and read using the rest mechanism. blobs, tables, and queues are all requested by HTTP operations in the form of URIs.. Net client can use ADO.. NET data services can also be directly called over HTTP.

In addition, Windows azure applications can also choose other storage mechanisms. For example, Windows azure platform also provides SQL azure database, which is a component similar to SQL database for access, you can store relational data on the cloud platform.

Management tools (fabric)

Fabric provides management tools for all windows azure applications and storage, including computers, switches, Server Load balancer, and so on, it can also browse stored data, monitor and record every minute operations of applications. You can also decide on the machine on which the application runs in fabric and manage the application through an xml configuration file.