Software as a Service (SaaS)
- Cloud computing service model where software applications are delivered over the internet on a subscription basis
- Provider hosts and maintains the application, infrastructure, and platform - users access via web browser or thin client
- Eliminates need for local installation, maintenance, and updates - everything handled by the service provider
- Multi-tenant architecture allows multiple customers to share the same application instance while keeping data isolated
Service Delivery Model
- Applications accessed through web browsers or dedicated client applications
- Provider manages all underlying infrastructure (servers, storage, networking, OS, middleware)
- Automatic updates and patches deployed by provider without user intervention
- Users only responsible for their data and user access management
Key Characteristics
- Subscription-based pricing model (monthly/annual fees rather than upfront licensing)
- Scalability handled automatically by provider based on demand
- Accessibility from any device with internet connection and compatible browser
- Built-in disaster recovery and backup capabilities managed by provider
- Integration capabilities through APIs (Application Programming Interfaces)
SaaS vs Other Cloud Models
| Model | User Manages | Provider Manages | Examples |
|---|---|---|---|
| SaaS | Data, Users | Everything else | Office 365, Salesforce, Gmail |
| PaaS | Applications, Data | Runtime, OS, Infrastructure | Azure App Service, Google App Engine |
| IaaS | OS, Applications, Data | Hardware, Virtualization | AWS EC2, Azure VMs |
Network Requirements
- Reliable internet connectivity essential (no internet = no access)
- Bandwidth considerations for multiple concurrent users
- Latency impacts user experience, especially for real-time applications
- Quality of Service (QoS) policies may be needed to prioritize SaaS traffic
Common SaaS Applications
- Productivity Suites: Microsoft Office 365, Google Workspace
- Customer Relationship Management (CRM): Salesforce, HubSpot
- Enterprise Resource Planning (ERP): NetSuite, SAP SuccessFactors
- Communication: Slack, Zoom, Microsoft Teams
- Email Services: Gmail, Outlook.com, Yahoo Mail
Vocabulary
Multi-tenancy: Architecture where single application instance serves multiple customers while keeping their data logically separated
API (Application Programming Interface): Set of protocols and tools that allow different software applications to communicate and integrate
Thin Client: Lightweight computer or application that depends on server-side processing rather than local resources
Subscription Model: Pricing structure based on recurring payments rather than one-time purchases
Service Level Agreement (SLA): Contract defining expected uptime, performance, and support levels from provider
Notes
- SaaS applications require constant internet connectivity - offline functionality often limited or non-existent
- Data sovereignty concerns when provider stores data in different geographic locations than user’s country
- Vendor lock-in risk - migrating data and processes away from SaaS provider can be complex and costly
- Security considerations: you’re trusting provider with your data - verify their compliance certifications (SOC 2, ISO 27001)
- Network planning: estimate bandwidth needs based on concurrent users and application types (video conferencing requires more than email)
- Consider hybrid approaches where critical applications remain on-premises while non-critical functions move to SaaS
- Evaluate integration capabilities before adoption - ensure SaaS applications can connect with existing on-premises systems
- Always have data backup and export strategies - don’t rely solely on provider’s backup systems