Software as a service

Software as a service
Name	Software as a service
Other names	On-demand software, Web-based software
Industry	Cloud computing
Area served	Global

Software as a service. It is a software licensing and delivery model in which applications are hosted by a provider and made available to customers over a network, typically the Internet. This model eliminates the need for organizations to install and run applications on their own computers or in their own data centers, shifting the responsibility for maintenance, ongoing operation, and support to the provider. The service is typically accessed by users using a thin client, such as a Web browser.

Definition and characteristics

The defining characteristic is the delivery of application functionality via a subscription model, rather than a perpetual license. Key attributes include a multitenant architecture, where a single instance of the software serves multiple customer organizations, and centralized hosting managed from a data center. Access is generally provided through a standardized Web browser or a lightweight API, with no requirement for local installation. This model is a primary component of the broader Cloud computing ecosystem, alongside Infrastructure as a service and Platform as a service.

History and development

The conceptual origins can be traced to the 1960s with IBM and other mainframe providers offering time-sharing and utility computing services. The modern incarnation began to take shape in the late 1990s with the expansion of the Internet and the advent of Application Service Providers like Salesforce, which pioneered enterprise CRM delivered entirely online. The term "Software as a Service" was popularized in a 2001 article by the Software & Information Industry Association. The subsequent proliferation of high-speed Internet and advancements in Web 2.0 technologies enabled the explosive growth of companies like Google with Google Apps and Microsoft with Microsoft 365.

Architecture and delivery models

SaaS applications are built on a multitenant architecture, where all users and applications share a single, common infrastructure and code base maintained centrally. This is distinct from single-tenant models used in traditional software. Delivery is facilitated through Cloud computing infrastructures provided by major vendors such as Amazon Web Services, Microsoft Azure, and the Google Cloud Platform. Integration with other services often occurs via APIs, and many providers offer Platform as a service environments for customization. The OpenAPI Specification has become a common standard for these interfaces.

Adoption and economic impact

Adoption has become ubiquitous across industries, driven by the shift to remote work and digital transformation initiatives. Enterprise software segments like CRM, ERP, and HRM are now dominated by SaaS models, with leaders including Salesforce, SAP, and Workday. The economic model has transformed the software industry, moving revenue from large upfront license fees to predictable recurring subscription revenue, impacting traditional vendors like Microsoft and Oracle. This shift has also lowered barriers to entry, fueling the growth of startups and changing Venture capital investment patterns.

Advantages and disadvantages

Primary advantages include lower initial costs, as it eliminates capital expenditure on hardware and software licenses, and simplified administration, with the provider handling updates, patches, and backups. It offers scalability and accessibility from any location with an Internet connection. Significant disadvantages revolve around Vendor lock-in, where migrating data between providers can be difficult and costly. Other concerns include reliance on the provider's SLA for uptime and performance, potential for unpredictable long-term costs, and limited customization compared to on-premises software.

Security and compliance considerations

Security responsibilities are shared under the Shared responsibility model, where the provider secures the infrastructure and application, while the customer is responsible for user access and data. Providers like Microsoft and AWS invest heavily in security certifications, often adhering to standards like ISO/IEC 27001, SOC 2, and the Payment Card Industry Data Security Standard. Data residency and sovereignty have become critical issues, governed by regulations such as the General Data Protection Regulation in the European Union and the Health Insurance Portability and Accountability Act in the United States. Customers must conduct due diligence on a provider's data breach history and disaster recovery capabilities.

Category:Cloud computing Category:Business models Category:Software distribution