Multi-Tenancy

Multi-tenancy is an architecture in which a single instance of a software application serves multiple customers. Each customer is called a tenant. Tenants may be given the ability to customize some parts of the application, such as color of the user interface (UI) or business rules, but they cannot customize the application’s code.

Multi-tenancy can be economical because software development and maintenance costs are shared. It can be contrasted with single-tenancy, an architecture in which each customer has their own software instance and may be given access to code. With a multi-tenancy architecture, the provider only has to make updates once. With a single-tenancy architecture, the provider has to touch multiple instances of the software in order to make updates.

In cloud computing, the meaning of multi-tenancy architecture has broadened because of new service models that take advantage of virtualization and remote access. A software-as-a-service (SaaS) provider, for example, can run one instance of its application on one instance of a database and provide web access to multiple customers. In such a scenario, each tenant’s data is isolated and remains invisible to other tenants.

Web Services

Web services is a special function that can be develop using any kind language  like C#,VB,Java etc.,  can be deployed on a server in such way that any application would be able to use it. Web Service is business logic component so Web service can be used inter application communication and cross business integration. To maintain the compatibility across various technology the web service code is translate  into an xml based language called WSDL(windows service definition language) because WSDL web services can cross the technology barriers.

The Communication Of Web Services is control by special protocol SOAP(Simple Object Access Protocol). It is combination of transmissions power of HTTP and representation ability of XML. The Job locating Web Services and making it available to an application is done by special service called UDDI(Universal Description Discovery Language).

They are two main ways to Consuming Web Services

1. HTTP-GET: In this method web service Directly loaded on the client browser either by typing the URL in the address bar or by clicking hyperlink. In this case Web Service provides readymade  default interface to interact with terminology.
2. HTTP-POST: In this method a customize html form will submit its data to web services and will receive the processing result.

A Web Service by default makes use of tempuri.org(universal resource  identifiers) as its xml namespace. It is highly recommended that the namespace  must be specified before the web services is made public.

Web Service extension is .asmx.

Why Clustered Index is must in Sql Azure?

When I started with Sql Azure and playing some T-Sql command in Sql Azure. I found an error when fired create table command.

Create table table_name (col1 data type, clo2 data type……)

And when I try to insert a data into table its gives a following error.

Figure: T-Sql Command in SQL Azure

It just because I’m not using clustered constraint means I am not mentioning any column primary key. It not happens with Sql server. Sql Azure Database does not support tables without clustered indexes. A table must have cluster index (constraint i.e. primary key) when use create table command if not create cluster index before insert command use for every table.

Example:

Figure:T-SQL Command in SQL Azure using Cluster Index

So what is need of Cluster Index in Sql Azure?

As we know Sql Azure have functionality of replication (i.e. 3 copy of database). Sql Azure requires cluster Index for Replication. Sql Azure keeping three replicas of data one primary replica and two are secondary replica. The Data pages are exactly same in all three replicas. In Sql Azure the ordering data pages is the key of replication that why need of Cluster Index in Sql Azure for every table.

Next time with new error with new query

Blg Files

The BLG file extension is associated with Microsoft Windows Operating System, concrete with Windows System Monitor (perfmon.exe).

The .blg files are used for saving Microsoft Windows Microsoft Windows binary performance logs. The .blg files contains a history of the computer resource utilization and performance, such as the amount of CPU, memory, and disk resources used by different programs. The .blg files are used analyse various server and computer loads and discover possible performance leaks.

The .blg files are stored in a proprietary binary format, but the format is different for different versions of Microsoft Windows. The .blg files can be converted to .csv files using the “relog” command at the command prompt in Windows. They also can be viewed in the Windows Administrative Tools.

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