AJAX Tutorial

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In this AJAX tutorial we discuss about asynchronous call for servers. AJAX, short form of Asynchronous JavaScript and XML, is a web development technique for creating interactive web applications.

AJAX meant to increase the web page’s interactivity, speed, and usability. AJAX is not a new programming language, but a new way to use existing standards. AJAX is the art of exchanging data with a server, and updating parts of a web page – without reloading the whole page.

AJAX allows you to send only important information to the server not the entire page. So only valuable data from the client side is routed to the server side. It makes your application interactive and faster.

Ajax uses XHTML for content and CSS for presentation, as well as the Document Object Model and JavaScript for dynamic content display.

AJAX is a web browser technology independent of web server software.

A user can continue to use the application while the client program requests information from the server in the background.

Intuitive and natural user interaction. No clicking required only Mouse movement is a sufficient event trigger.

Data-driven as opposed to page-driven.

Used?
There are many web applications now a days using Ajax technologies in the web application as like gmail, facebook, twiter, etc.


Contents for AJAX
AJAX Intro
Synchronous and Async in AJAX
AJAX XMLHttp
AJAX Request
AJAX Response

Community Cloud Model in Cloud Computing

Community cloud shares infrastructure between several organizations from a specific community with common concerns (security, compliance, jurisdiction, etc.), whether managed internally or by a third-party and hosted internally or externally. The costs are spread over fewer users than a public cloud (but more than a private cloud), so only some of the cost savings potential of cloud computing are realized.

Community Cloud Model in Cloud Computing

Benefits of Community Cloud Model
Cost Effective-
Community cloud offers same advantage as that of private cloud at low cost.

Sharing Between Organizations-
Community cloud provides an infrastructure to share cloud resources and capabilities among several organizations.

Security-
Community cloud is comparatively more secure than the public cloud.

Disadvantages of Community Cloud Model
Data accessible between Organizations-
Since all data is housed at one location, one must be careful in storing data in community cloud because it might be accessible by others.

Challenging in Responsibilities-
It is also challenging to allocate responsibilities of governance, security and cost.

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Hybrid Cloud Model in Cloud Computing

In this cloud tutorial we will discuss about the Hybrid Cloud Model, it is the mixture of public and private cloud. Non-critical activities are performed by public cloud while critical activities are performed by private cloud.

Hybrid Cloud Model in Cloud Computing

Benefits of Hybrid Cloud Model
Scalable-
It provides both the features of public and private cloud scalability.

Security-
Private cloud in hybrid cloud ensures higher degree of security.

Flexible and secure-
It provides secure resources because of private cloud and scalable resources because of public cloud.

Cost effective-
It is having less cost as compared to private cloud.

Disadvantages of Hybrid Cloud Model
Network Issue –
Networking becomes complex due to presence of private and public cloud.

Security Compliance-
It is necessary to ensure that cloud services are compliant with the security policies of an organization.

Infrastructural Dependency-
The hybrid cloud model is dependent on internal IT infrastructure, therefore it is necessary to ensure redundancy across data centers.

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Private Cloud Model in Cloud Computing

In this cloud tutorial we will talking about one of the cloud model is private cloud model in the Private Cloud allows systems and services to be accessible with in an organization. The Private Cloud is operated only within a single organization. However, It may be managed internally or by third-party.

Private Cloud Model in Cloud Computing

Benefits of Private Cloud Model
High security and privacy-
Private cloud resources are shared from distinct pool of resources and hence highly secured.

More Control-
Private clouds have more control on its resources and hardware than public cloud because it is accessed only within the boundary of an organization.

Cost & Energy Efficiency-
Private cloud resources are not as cost effective as public clouds but they offer more efficiency than public cloud.

Disadvantages of Private Cloud Model
Restriction-
Private cloud is only accessible locally and it is very difficult to deploy globally.

Less Scalability-
Private clouds are scaled only within capacity of internal hosted resources.

Additional Skills-
In order to maintain cloud deployment, organization requires more skilled and expertise.

Inflexible Costing-
In order to fulfill demand, purchasing new hardware is very costly.

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Public Cloud in Cloud Computing

A cloud is called a “public cloud” when the services are rendered over a network that is open for public use. Technically there may be little or no difference between public and private cloud architecture, however, security consideration may be substantially different for services (applications, storage, and other resources) that are made available by a service provider for a public audience and when communication is effected over a non-trusted network. Generally, public cloud service providers like Amazon AWS, Microsoft and Google own and operate the infrastructure and offer access only via Internet.

Public Cloud in Cloud Computing

Benefits of Public Cloud Model-
1. Low Cost
Public cloud is having low cost as compared to private or hybrid cloud, because it shares same resources with large number of consumer.

2. Reliable
Public cloud provides large number of resources from different locations, if any of the resource fail, public cloud can employ another one.

3. Flexible
It is very easy to integrate public cloud with private cloud and hence it gives flexible approach to consumers.

4. Location Independent
It ensures the independency of location, because public cloud services are delivered through Internet.

5. High Scalability
Cloud resources are available as per the demand from the pool of resources that means they can be scaled up or down according to the requirement.

Risks of Public Cloud
Here are the disadvantages of public cloud model:

1. LOW SECURITY
In public cloud model, data is hosted off-site and resources are shared publicly, therefore does not ensure higher level of security.

2. LESS CUSTOMIZABLE
It is comparatively less customizable than private cloud.

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Network-as-a-Service (NaaS)

In cloud computing Network as a Service (NaaS) is provide remote network infrastructure as service securely with less cost. NaaS makes it possible to deploy custom routing protocols.

NaaS provide virtual network Infrastructure to provide network service to the business consumers. NaaS manage the network and security related responsibilities and also manage resources uses by consumers and decreases the workload. NaaS is also based on pay per use model.

Benefits of Network as-a-Service:
1. Near you and your end users.
More than 95% of the world’s enterprise business users are within 20 milliseconds from any of our POPS. Multi-segment TCP optimization technology minimizes the application performance impact of packet loss on both the first and last mile.

2. Service, not boxes.
You subscribe for the bandwidth you need, when you need it, instead of building your WAN for future growth. We offer global on-demand capacity, so you can quickly add bandwidth at any location.

3. Connect in minutes.
You can be up and running in minutes, not the days, weeks or even months it can take to deploy MPLS. You simply connect into the network using an IPSec-capable edge device over your business-class Internet connection (or a direct L2 connection) to one or more of our nearest POPs.

4.QoS.
Our network honors your Quality of Service (QoS) markings to prioritize business-critical applications by class (such as for real-time applications) over other data traveling across the network, guaranteeing performance levels. The ability to burst above your subscription provides even more capacity for peak loads without additional cost.

5. Security.
We can connect an IPSec VPN directly into the network at the closest POP for those cloud services that require secure private access. For us, this is as simple as setting up any other location on the private network.

6. Visibility.
Our web-based portal delivers end-to-end network-wide visibility. With our service-based offering, we do all of the management for you, providing 24/7 support via Network Operations Centers (NOCs) located on opposite sides of the world.

Some service models are
1. Virtual Private Network (VPN): Extends a private network and the resources contained in the network across networks like the public Internet.

2. Bandwidth on demand (BoD): Technique by which network capacity is assigned based on requirements between different nodes or users.

3. Mobile network virtualization: Model in which a telecommunications manufacturer or independent network operator builds and operates a network (wireless, or transport connectivity) and sells its communication access capabilities to third parties (commonly mobile phone operators) charging by capacity utilization.

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Identity as a Service (IDaaS)

Suppose one IT Company have thousands of Employees and that IT company share resources of multiple tasks with different login ID and password. In my office Times have different portal like TJ, MB, IndiaTimes, TOI, SM etc. these portal have login functionality for all users so its very difficult to manage all login IDs for each portal.

To solve above problems, a new technique emerged which is known as Identity as a Service (IDaaS). Identity as a Service (IDaaS) is an authentication infrastructure that is built, hosted and managed by a third-party service provider. IDaaS can be thought of as single sign-on (SSO) for the cloud.

Single Sign-On (SSO)
To solve the problem of using different username & password combination for different servers, companies now employ Single Sign-On software, which allows the user to login only one time and manages the user’s access to other systems.

SSO has single authentication server, managing multiple accesses to other systems, as shown in the following diagram:

Identity as a Service (IDaaS)


Working of SSO
Following steps explain the working of Single Sign-On software:
1. User logs into the authentication server using a username and password.
2. The authentication server returns the user’s token.
3. User sends the token to intranet server.
4. Intranet server sends the token to the authentication server.

Authentication server sends the user’s security credentials for that server back to the intranet server.

IDaaS

Benefits of IDaaS Cloud Computing layer
1. Increased site conversation rates.
2. Access to greater user profile content.
3. Fewer problems with lost passwords.
4. Ease of content integration into social networking sites.

Examples-
It offers users to login into multiple websites with single account. Google, Yahoo!, Flickr, MySpace, WordPress.com are some of the companies that support OpenID.

References
1. http://ccskguide.org/cloud-identity-as-a-service-idaas/

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Software as a Service (SaaS)

Software as a Service(SaaS) is one of the most important module or layer of cloud computing. SaaS means Software on demand, it provide distributed software to business customer. In SaaS, software and associated data are centrally hosted on the cloud server. SaaS is accessed by users using a thin client via a web browser. Some of the below components which use as SaaS-

1. Billing and Invoicing System
2. Customer Relationship Management (CRM) applications
3. Help Desk Applications
4. Human Resource (HR) Solutions

SaaS is service oriented architecture (SOA). Software as a Service (SaaS) delivers business processes and applications, such as CRM, collaboration, and email, as standardized capabilities for a usage-based cost at an agreed, business-relevant service level. SaaS provides significant efficiencies in cost and delivery in exchange for minimal customization and represents a shift of operational risks from the consumer to the provider. All infrastructure and IT operational functions are abstracted away from the consumer.

Software as a Service (SaaS)

Benefits of SaaS cloud computing layer
1. No additional hardware costs-
the processing power required to run the applications is supplied by the cloud provider.

2. No initial setup costs-
applications are ready to use once the user subscribes.

3. Pay for what you use-
if a piece of software is only needed for a limited period then it is only paid for over that period and subscriptions can usually be halted at any time.

4. Usage is scalable-
if a user decides they need more storage or additional services, for example, then they can access these on demand without needing to install new software or hardware.

5. Updates are automated-
whenever there is an update it is available online to existing customers, often free of charge. No new software will be required as it often is with other types of applications and the updates will usually be deployed automatically by the cloud provider.

6. Cross device compatibility-
SaaS applications can be accessed via any internet enabled device, which makes it ideal for those who use a number of different devices, such as internet enabled phones and tablets, and those who don’t always use the same computer.

7. Accessible from any location-
rather than being restricted to installations on individual computers, an application can be accessed from anywhere with an internet enabled device.

8. Applications can be customized and white-labelled-
with some software, customisation is available meaning it can be altered to suit the needs and branding of a particular customer.

Risks of SaaS cloud computing layer-
1. Security
Actually data is stored in cloud, so security may be an issue for some users. However, cloud computing is not more secure than in-house deployment. Learn more cloud security.

2. Latency issue
Because the data and application are stored in cloud at a variable distance from the end user, so there is a possibility that there may be more latency while interacting with the application than a local deployment. So, SaaS model is not suitable for applications whose demand response times are in milliseconds.

3. Total Dependency on Internet
Without internet connection, most SaaS applications are not usable.

4. Portability between SaaS vendors is difficult
Transferring workloads from one SaaS cloud to another is not so easy because work flow, business logics, user interfaces, support scripts can be provider specific.

References
1. http://en.wikipedia.org/wiki/Cloud_computing#Software_as_a_service_.28SaaS.29
2. http://en.wikipedia.org/wiki/Software_as_a_service

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Platform as a Service (PaaS)

Platform as a Service, often simply referred to as PaaS, is a category of cloud computing that provides a platform and environment to allow developers to build applications and services over the internet. PaaS services are hosted in the cloud and accessed by users simply via their web browser.

Platform as a Service (PaaS) delivers application execution services, such as application runtime, storage, and integration for applications written for a pre-specified development framework. PaaS provides an efficient and agile approach to operate scale-out applications in a predictable and cost-effective manner. Service levels and operational risks are shared because the consumer must take responsibility for the stability, architectural compliance, and overall operations of the application while the provider delivers the platform capability (including the infrastructure and operational functions) at a predictable service level and cost.

Platform as a Service allows users to create software applications using tools supplied by the provider. PaaS services can consist of preconfigured features that customers can subscribe to; they can choose to include the features that meet their requirements while discarding those that do not. Consequently, packages can vary from offering simple point-and-click frameworks where no client side hosting expertise is required to supplying the infrastructure options for advanced development.

The following diagram shows how PaaS offers an API and development tools to the developers and how it helps the end user to access business applications.

Platform as a Service

Benefits of PaaS cloud computing layer

1) Simplified Development
Developers can focus on development and innovation without worrying about the infrastructure.

2) Lower risk
No requirements of up-front investment in hardware and software. Developers only need a PC and an internet connection to start building applications.

3) Prebuilt business functionality
Some PaaS vendors also provide already defined business functionality so that users can avoid building everything from very scratch and hence can directly start the projects only.

4) Instant community
PaaS vendors frequently provides online communities where developer can get the ideas, share experiences and seek advice from others.

5) Scalability
Applications deployed can scale from one to thousands of users without any changes to the applications.

Disadvantages of PaaS Layer

1) Vendor lock-in
One have to write the applications according to the platform provided by PaaS vendor so migration of an application to another PaaS vendor would be a problem.

2) Data Privacy
Corporate data, whether it can be critical or not, will be private so if it is not located within the walls of the company there can be a risk in terms of privacy of data.

3) Integration with the rest of the systems applications
It may happen that some applications are local and some are in cloud. So there will be chances of increased complexity when we want to use data which in the cloud with the local data.

PaaS Types
Based on the functions, the PaaS can be classified into four types as shown in the following diagram:

Platform as a Service  (PaaS)

Top vendors who are providing PaaS cloud computing platform

  • Google Apps Engine (GAE)
  • SalesFroce.com
  • Windows Azure
  • AppFog
  • Openshift
  • Cloud Foundary from VMware

References
1. http://en.wikipedia.org/wiki/Platform_as_a_service

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Infrastructure as a service (IaaS)

In cloud computing there are many layers exist in picture. IaaS is one of most important layer which provide IT infrastructure to the customer organization such as servers, networking, processing, storage, virtual machines and other resources. Customers access these resources over internet i.e. cloud computing platform, on a pay-per-use model. Infrastructure as a Service is sometimes referred to as Hardware as a Service (HaaS).

Infrastructure as a service (IaaS)

Salient examples of how IaaS can be utilized by enterprise:

Cloud hosting-
the hosting of websites on virtual servers which are founded upon pooled resources from underlying physical servers. A website hosted in the cloud, for example, can benefit from the redundancy provided by a vast network of physical servers and on demand scalability to deal with unexpected demands placed on the website.

Enterprise infrastructure-
by internal business networks, such as private clouds and virtual local area networks, which utilise pooled server and networking resources and in which a business can store their data and run the applications they need to operate day-to-day. Expanding businesses can scale their infrastructure in accordance with their growth whilst private clouds (accessible only by the business itself) can protect the storage and transfer of the sensitive data that some businesses are required to handle.

Virtual Data Centers (VDC)-
a virtualised network of interconnected virtual servers which can be used to offer enhanced cloud hosting capabilities, enterprise IT infrastructure or to integrate all of these operations within either a private or public cloud implementation.

IaaS offering can deliver the following features and benefits:

Scalability-
resource is available as and when the client needs it and, therefore, there are no delays in expanding capacity or the wastage of unused capacity

No investment in hardware-
the underlying physical hardware that supports an IaaS service is set up and maintained by the cloud provider, saving the time and cost of doing so on the client side.

Utility style costing-
the service can be accessed on demand and the client only pays for the resource that they actually use

Location independence-
the service can usually be accessed from any location as long as there is an internet connection and the security protocol of the cloud allows it.

Physical security of data centre locations-
services available through a public cloud, or private clouds hosted externally with the cloud provider, benefit from the physical security afforded to the servers which are hosted within a data centre

No single point of failure-
if one server or network switch, for example, were to fail, the broader service would be unaffected due to the remaining multitude of hardware resources and redundancy configurations. For many services if one entire data center were to go offline, nevermind one server, the IaaS service could still run successfully.

Disadvantages of IaaS cloud computing layer
There is a risk of IaaS cloud computing platform vendor by gaining the access to the organization???s data. But it can be avoided by opting for private cloud.

1) IaaS cloud computing platform model is dependent on internet availability.
2) It is also dependent on the availability of virtualization services.
3) IaaS cloud computing platform can limit the user privacy and customization options.

Some key point remember about IaaS-
1. IaaS cloud computing platform may not eliminate the need for an in-house IT department. It will be needed to monitor or control the IaaS setup. IT salary expenditure might not reduce significantly, but other IT expenses can be reduced.

2. The IaaS cloud computing platform vendor can get access to your sensitive data. So, engage with the credible companies or organizations. Study their security policies and precautions.

3. IaaS cloud computing platform cannot replace traditional hosting method but it provides more than that and each resources which are used are predictable as per the usage.

Vendors who provides IaaS-

1. Amazon Web Services
Elastic, Elastic Compute Cloud (EC2) MapReduce, Route 53, Virtual Private Cloud, etc.

2. Netmagic Solutions
Netmagic runs from data centers in Mumbai, Chennai, and Bangalore, and a virtual data center in the United States. Plans are underway to extend services to West Asia.

3. Reliance Communications
RIDC supports both traditional hosting and cloud services, with data centers in Mumbai, Bangalore, Hyderabad, and Chennai. The cloud services offered by RIDC include IaaS and SaaS.

4. Sify Technologies (Sify IaaS)
Sify’s cloud computing platform is powered by HP’s converged infrastructure. The vendor offers all three types of cloud services: IaaS, PaaS, and SaaS.

References
1. http://en.wikipedia.org/wiki/Cloud_computing#Infrastructure_as_a_service_.28IaaS.29

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