Windows Azure for Developers Task 3: Understanding Windows Azure
An application designed and developed to be as hosted service
for windows azure consist of
1. Managed Code
2. XML file for
Managed codes are mapped into
XML files are mapped into different configuration settings.
If we see the below diagram it explains all the components mainly involved
in Windows Azure application.
Note: This image taken from Windows Azure SDK
We will examine each
component of above diagram one by one.
The first thing is Roles
there types of Roles
1. Web Role
2. Worker Role
3. VM Role
1. This is role customized for IIS.
2. If we choose
this type of Role automatically IIS setup is configured for this.
role mainly takes input.
4. This role is configured for HTTP request.
5. This contains web sites or other codes that is supported by IIS.
This mainly contains ASPX pages or it may contain WCF Services also. Any
application supported by IIS can be used as Web Role.
7. Any application
can be used as Web Role if it supports HTTP protocol.
8. When we use WCF
Service for Web Role in Windows Azure we need to make sure that binding used in
WCF service is basicHttpBinding
We cannot use another binding with WCF
Service as Web Role. Advancement in Web Role in Windows Azure SDK 1.3
1. It got full capability of IIS.
2. Web Applications and sites
run fully under IIS.
3. Web Roles uses the application domain in the same
way as of IIS.
Biggest advantage is that now we could have multiple sites or
application is a single Web Role.
While creating Azure project we can select
the type of Web Role we want for the application. Installed templates are
1. ASP.Net Web Role
2. ASP.Net MVC Web Role
3. WCF Service Web
4. CGI Web Role
creation of Windows Azure project, you can see there are two types of
configuration files created for you.
file, we can give the number of Web Role
It is mainly useful for background work. The main point to be
noticed here is that Worker Role does not support IIS. So it is very much
capable to process any type of application including unmanaged code. Worker
role does not directly interact with the user so it is very useful when it come
for asynchronous long processing task.
Mainly Worker Roles are useful
1. Useful in the task where user has not to wait for.
2. Useful for
3. Useful to run non HTTP service like TCP services.
4. To host the application does not require user input. Difference
between Worker Role and Web Role
Let us understand some differences
between Web Role and Worker Role
1. Web Role is web application which gets
HTTP Input from the user and it is supported by IIS. Worker Role has not
supported IIS. This is the main difference between Web Role and Worker Role.
2. Web Role faces the user interface whereas Worker Role gets input from
Web Role and mainly performs the batch operations asynchronously.
3. In Web
Role Threading is managed by IIS whereas in Worker Role Threading is managed by
developer or ourselves.
4. In Worker role we must need to provide Run
method to start the process.
5. The security parameter is not same in
between Web Role and Worker Role.
6. ACL [Access Control List] for
certificates is supported by default for IIS and network services by default
whereas in Worker Role developer has to manage it.
In csdef file Worker
Role is defined like below , name of the worker role is WokerRole1
Role class mainly contains two methods VM
Third type of role is VM Role. This is very special types of role
and it mainly deals with operating system up gradation in virtual machines.
Web Role and Worker Role run on a virtual machine whereas VM Role is a
virtual machine which gives full control of the operations on virtual machines.
Using VM Role we control the operating system and any up gradation in
virtual machine operating system is instance of VM Role. This role is suited
for migrating application to run as hosted service in Windows Azure.
Role can be defined as below
Now since we have understood the three different types of Roles.
Let us have a look on two types of configuration files involved in Windows Azure
file can be updated without stopping the azure service. This file mainly
contains information about
1. Number of Role instances
Value for the different types of setting.
Instance count says number of instance of the Web Role or Worker Role will be
2. In above configuration file we can see that application is
using local development. ServiceDefinition.csdef
contains below information
1. Various ROLES used by the service
2. Information about Certificates used in the service.
Input and Internal End Points for the service
4. Local disk storage
needed by the service
5. Configuration setting that would be used by
different Roles .
This configuration file defines the Web Role or Worker
Role. Let us understand each segment of this file one by one.
segment contains the definitions for site and web applications. These sites and
web applications are hosted in IIS 7.
are two types of End Points in this configuration file, Input End Point and
Internal End Point. Input End Point
contains the definition of
endpoint that is used to contact hosted service. Internal End
contains the definition that is used by roles to communicate with each
segment contains the certificate needed for a role.
segment contains definition of imported rules. Storage Service
The last segment of Azure Application is Azure Storage service.
There are three types of azure services
1. For unstructured Data
2. For structured Data ( TABLES
messages between application and services (QUEUES
mainly for used for large storage of Data. There are two types of BLOG storage,
Block BLOG and PAGE BLOB. Azure Tables are used to store structured data. CRUD
operations can be performed using ODATA protocol or using the same syntax used
for WCF Data Service. Each row in the Azure table uniquely identified by Row
key and Partition Key.
For storage purpose we
can use SQL Azure also. Conclusion
In this article we saw
an introduction of Windows Azure application. This article was more of
theoretical. In next article of this series we will explore Windows Azure
application in a walkthrough way . Thanks for reading.