There has been confusion about the meaning of software as a service (SaaS) and on-demand. This confusion, further muddled by the existence of the former hosting and application service provider (ASP) models, has bred a range of often fuzzy and sometimes incorrect assumptions. For many it is difficult to ascertain whether SaaS or on demand imply that
1. the software application is hosted; that is some kind of hosting middleman is needed to provide users with access to the software, at a guaranteed level of service;
2. software is available in a hosted-form only, off-site, and is accessible via a Web browser, through a self-service type model, not through compact discs (CD) or uploads; or
3. software is available via a subscription model, where users pay on a daily, weekly, monthly, or per usage basis.
This is Part Two of the four-part Software as a Service Is Gaining Ground series.
Certainly, the recent generation of software, designed from scratch to be delivered as a service, fundamentally differs from traditional hosting models. This new generation offers a number of benefits that those earlier delivery models could not. Namely, although SaaS hosting models are still evolving, many of the technological problems that spoiled the first wave of ASPs have been or are being solved. For instance, in addition to improvements in security and reduced prices for bandwidth that bode well for hosting adoption, hosted software finally looks and feels more like traditional rich user interface client/server applications. This is because of tools such as JavaScript that provide error-checking and validation on the client side. Additionally, and possibly even more importantly, the development of dynamic hypertext markup language (DHTML) has allowed Web content to change every time it is viewed, by enabling a Web page to react to user input without sending requests to the Web server. This, in particular, has introduced a degree of interactivity to Web-based applications that was simply not possible a few years ago. Back then, users were either forced to fill in and submit cumbersome hypertext markup language (HTML) forms, or they had to run additional thin client software, such as Citrix MetaFrame, on their desktops. Neither of these approaches was satisfactory, despite the fact that while thin client software seemingly promised a good solution, it still had a number of shortcomings.
First, thin client software increased costs because the software had to be licensed on a per user basis, an idea that the hosting model was to do away with. This often caused the cost of the Citrix MetaFrame license to account for more than half of a less-than-enticing monthly fee. Second, because the screen was effectively being "rendered" miles away from where the user was actually located, it was slow and increased the load on the network at a time when bandwidth was at a premium price. Finally, users still had to run and maintain the proprietary thin client software on their desktops, defeating the object of running server-centric, Web-based software. As a result, costs were not being reduced by as much as originally promised.
However, with the advent of new tools, this has been ameliorated a great deal. In terms of the browser, support for very advanced graphics is still lacking, while the need for complex interactions on the client side has been mitigated by DHTML's help with minimization of server round-trips and page refreshes. One should expect more developments enabling more sophisticated interaction scenarios in the foreseeable future. Basically, well devised SaaS applications should be able to leverage rich user interface metaphors, without necessarily mandating them.
Based on this, one can define SaaS as software components that are developed or purchased and hosted by an independent service provider, and that are billed on a resource usage or per user basis (which can be changed and is not a fixed monthly fee). These software components do not require any user-owned or managed infrastructure, except for Internet access. The software is supported on a virtual infrastructure platform made up of physical equipment, such as networks and servers; storage located within commercial data centers and logical applications, such as Web sites; applications; and database software, which runs on the physical hardware and is delivered by the independent third party.
Different from Traditional Application Hosting
It is important to distinguish SaaS from traditional application hosting. Typically, a traditional hosting lease means that the user still buys the software and hardware but finances it in monthly payments. Under these terms, the hosting user enterprise owns rights to the hosted software, but the subscription is essentially a payment to third party to manage the hardware and infrastructure aspect of the installation. In the ASP model, the ASP vendor typically owns the software. The subscription buys the right to access the software for the period of the subscription on either a time basis or on a usage basis (e.g., so much for such a transaction).
Conversely, in the SaaS model, there is no upfront capital investment, and no hardware or software to purchase. Users and their implementation partners (Web developers and systems integrators) may only customize and manage the content, design, and business logic of their Web sites or pages. A good example of this is the way banks use check processing services. While software is used to run those services, banks are not paying to access the software, but are rather paying for a check clearing service. Another example would be the way the airlines use global distribution systems such as Sabre.
There are also technical differences between SaaS and application hosting. In the traditional hosting model, referred to as single tenancy, a service provider licenses an application from an independent software vendor (ISV) and remotely hosts and manages the application (possibly via an ASP), typically for a start-up charge and a monthly maintenance fee. In this one-to-one model, despite high availability and a lower risk of security breaches and service outages, users would often find themselves stuck in situations where they could not roll out new features quickly or respond nimbly to fluctuating customer demand.
SOURCE:-
http://www.technologyevaluation.com/research/articles/what-is-software-as-a-service-18454/
1. the software application is hosted; that is some kind of hosting middleman is needed to provide users with access to the software, at a guaranteed level of service;
2. software is available in a hosted-form only, off-site, and is accessible via a Web browser, through a self-service type model, not through compact discs (CD) or uploads; or
3. software is available via a subscription model, where users pay on a daily, weekly, monthly, or per usage basis.
This is Part Two of the four-part Software as a Service Is Gaining Ground series.
Certainly, the recent generation of software, designed from scratch to be delivered as a service, fundamentally differs from traditional hosting models. This new generation offers a number of benefits that those earlier delivery models could not. Namely, although SaaS hosting models are still evolving, many of the technological problems that spoiled the first wave of ASPs have been or are being solved. For instance, in addition to improvements in security and reduced prices for bandwidth that bode well for hosting adoption, hosted software finally looks and feels more like traditional rich user interface client/server applications. This is because of tools such as JavaScript that provide error-checking and validation on the client side. Additionally, and possibly even more importantly, the development of dynamic hypertext markup language (DHTML) has allowed Web content to change every time it is viewed, by enabling a Web page to react to user input without sending requests to the Web server. This, in particular, has introduced a degree of interactivity to Web-based applications that was simply not possible a few years ago. Back then, users were either forced to fill in and submit cumbersome hypertext markup language (HTML) forms, or they had to run additional thin client software, such as Citrix MetaFrame, on their desktops. Neither of these approaches was satisfactory, despite the fact that while thin client software seemingly promised a good solution, it still had a number of shortcomings.
First, thin client software increased costs because the software had to be licensed on a per user basis, an idea that the hosting model was to do away with. This often caused the cost of the Citrix MetaFrame license to account for more than half of a less-than-enticing monthly fee. Second, because the screen was effectively being "rendered" miles away from where the user was actually located, it was slow and increased the load on the network at a time when bandwidth was at a premium price. Finally, users still had to run and maintain the proprietary thin client software on their desktops, defeating the object of running server-centric, Web-based software. As a result, costs were not being reduced by as much as originally promised.
However, with the advent of new tools, this has been ameliorated a great deal. In terms of the browser, support for very advanced graphics is still lacking, while the need for complex interactions on the client side has been mitigated by DHTML's help with minimization of server round-trips and page refreshes. One should expect more developments enabling more sophisticated interaction scenarios in the foreseeable future. Basically, well devised SaaS applications should be able to leverage rich user interface metaphors, without necessarily mandating them.
Based on this, one can define SaaS as software components that are developed or purchased and hosted by an independent service provider, and that are billed on a resource usage or per user basis (which can be changed and is not a fixed monthly fee). These software components do not require any user-owned or managed infrastructure, except for Internet access. The software is supported on a virtual infrastructure platform made up of physical equipment, such as networks and servers; storage located within commercial data centers and logical applications, such as Web sites; applications; and database software, which runs on the physical hardware and is delivered by the independent third party.
Different from Traditional Application Hosting
It is important to distinguish SaaS from traditional application hosting. Typically, a traditional hosting lease means that the user still buys the software and hardware but finances it in monthly payments. Under these terms, the hosting user enterprise owns rights to the hosted software, but the subscription is essentially a payment to third party to manage the hardware and infrastructure aspect of the installation. In the ASP model, the ASP vendor typically owns the software. The subscription buys the right to access the software for the period of the subscription on either a time basis or on a usage basis (e.g., so much for such a transaction).
Conversely, in the SaaS model, there is no upfront capital investment, and no hardware or software to purchase. Users and their implementation partners (Web developers and systems integrators) may only customize and manage the content, design, and business logic of their Web sites or pages. A good example of this is the way banks use check processing services. While software is used to run those services, banks are not paying to access the software, but are rather paying for a check clearing service. Another example would be the way the airlines use global distribution systems such as Sabre.
There are also technical differences between SaaS and application hosting. In the traditional hosting model, referred to as single tenancy, a service provider licenses an application from an independent software vendor (ISV) and remotely hosts and manages the application (possibly via an ASP), typically for a start-up charge and a monthly maintenance fee. In this one-to-one model, despite high availability and a lower risk of security breaches and service outages, users would often find themselves stuck in situations where they could not roll out new features quickly or respond nimbly to fluctuating customer demand.
SOURCE:-
http://www.technologyevaluation.com/research/articles/what-is-software-as-a-service-18454/
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