What are the tenets of SaaS?

The architecture of software as a service (SAAS) is a significant concept to grasp as the business is turning into a software as a service, making it of great importance to those in charge Chief Technology Officer (CTO), software as a service startups, or IT managers. Among the most important concepts in this so-called tenant of SaaS that regulates the way the data is handled and is separated. Such knowledge is needed in order to make strategic cost, security, scalability and customization choices. 

In our study that involves the research of the SaaS and cloud technologies, we determine that the choice of tenancy model is a ground-level selection that determines the overall lifecycle of a product and the market positioning. 

What is a SaaS tenant?

In the most basic definition, a SaaS tenant is a consumer an organization, or a category of users, using a SaaS application. An example is when a company subscribes to Salesforce, such a firm is a tenant. 

One of the most popular comparisons is that of a multi-tenant SaaS application and an apartment building. 

•  The infrastructure: The servers and databases (the underlying infrastructure) of the SaaS application.
•  The tenants: A subscribing customer, be it a business or a team.
•  The apartments: the logically separated, individual space of each tenant in the common application. 

The tenants have a common underlying infrastructure but the data and settings are logically isolated to provide privacy and security. Among the examples of companies that sell SaaS products are Salesforce, Slack, HubSpot, Zoom, and Gmail. 

Types of SaaS tenancy models

Multi-tenant SaaS

With the multi-tenant model, an instance of the application and the database is shared by more than one customer. Tenant information is stored on common resources but is physically partitioned by some unique identifier to the tenant. 

Benefits:

• Economically efficient: This means that the shared infrastructure will mean the operational costs will be low, thus the product will be affordable to the customers.
• Very scalable: It is quick and simple to accommodate new customers. The provider merely delivers a new slice of the shared application, and not a complete new instance.
• Reduced maintenance overhead: Updates, bug patches and security patches are installed once and made available to all tenants at the same time which makes it easier to manage.
• Quick innovation: The provider will be able to deliver new features to the entire user base simultaneously, speeding up the development process. 

Drawbacks:

• Limitations of customization: Since a single code base is shared between tenants that in general cannot be highly customized.
• Security threat: Security architecture is very essential to avoid data leakage among tenants.
•  Bothering neighbor problems: Intense utilization by one tenant may occasionally affect the performance of other tenants sharing the same facilities. 

Examples: The multi-tenant architecture is used in most current SaaS products, including Salesforce, Slack, and Zoom. 

Single-tenant SaaS

With a single-tenant system, a customer is supplied with a dedicated application of the software and its infrastructure. It implies that every tenant is separated to an application and a data base. 

Benefits:

• Isolation of maximum data: The physical isolation of resources implies that a security breach affecting one tenant does not affect the other tenant.
•  More control and customization: Tenants can be offered far more control of their software instance, such as making bespoke requests as to which version or which integrations.
•  Improved performance: Noisy neighbor effect is nonexistent, and the performance of a specific tenant is more predictable.
•  Easier regulatory compliance: Strict data regulations, like those enforced by the healthcare or financial industry, can be better served by single-tenancy in order to comply with such regulations as HIPAA or GDPR. 

Drawbacks:

• Increased cost: The requirement of having dedicated infrastructure per customer causes an enormous increase in the cost to the provider and the customer.
•  Increased maintenance cost: Each instance of the customer has to be maintained and updated separately by the provider, making this more complex and potentially slowing down the deployment time.
• Complex scalability: It is more complicated and resource-consuming to scale a high number of individual instances. 

Example: A single-tenancy is also available as a premium on some platforms, especially those with highly regulated enterprise customers. Some examples might include on-premise managed or self-hosted solutions, particular to clients.

Comparison of tenancy models

Advantages of multi-tenant SaaS.

Multi-tenancy is an effective resource optimization and fast development architecture to SaaS providers and their customers. The core benefits include: 

• Cost savings: SaaS providers are able to work with much lower overhead since they share the same infrastructure which lets them give their customers comparatively lower prices.
• Scalability and faster updates: Release updates or implement new features to one code base is much more efficient than updating and dealing with individual cases in each instance. This enables the provider to be innovative and scale at a greater rate.
• Simplified maintenance: Updates, patches and maintenance are centralized and applied at once which is beneficial to all tenants at once and reduces disruption. 

Case study: Salesforce and its management of the thousands of tenants.

With Salesforce being one of the first to develop the multi-tenant model, it successfully handles its huge clientele with an architecture that is metadata-driven. This architecture keeps the core engine of an application isolated as well as the customizations and data of tenants. Salesforce stores this as metadata rather than creating a separate table in the database with each customization. At runtime, the system takes advantage of this metadata and generates the unique and customized view of the application to a customer as he/she logs in. This enables them to scale effectively as evidenced by their capacity to offer the same reliable platform to thousands of tenants that have distinctive settings. 

Best practices of SaaS tenant management.

A multi-tenant SaaS needs to be implemented with a lot of planning to make sure that it is secure, the performance is maintained, and the scalability is achieved.

• Isolation and encryption: Be sure that the data of every tenant is logically segregated and to provide maximum security, they will have to be encrypted both in transit and at rest. This secures confidential data and assists in addressing the compliance requirements such as HIPAA and GDPR.
• Role-based access control (RBAC): This is to implement a granular access control measure to such an extent that only users have access to data that is pertinent to their assigned role and tenant. An example of this is a hospital that can develop a role named Nurse, which will be capable of seeing the records of the patients but not billing information.
• Monitors User usage: Monitor consumption of resources by individual tenants in real time to detect and avoid performance bottlenecks.
• Automate provisioning: Tenants should be provisioned on autopilot, in order to make the setup process smooth and efficient. This may involve automated resource distribution and quotas being enforced in the first place. 

SaaS tenant vs user

One of the most frequent misunderstandings in SaaS world is that of a tenant and a user. This can be easily explained by the fact that a tenant is an organization or a customer and a user is an account holder in the organization. 

• Case in point: Company A might be one of the tenants of Zoom. The company would have 500 employees whose individual accounts would also be personal users within a tenant.
• Security implications There is a security and administration boundary of a tenant. Meanwhile, the administrators of the tenant assign the permissions to a user with the help of role-based access control (RBAC). A user in Company A will in no way be able to access the information of a user in Company B. 

SaaS tenant management issues.

Although multi-tenancy has great advantages, it presents certain management issues that are to be dealt with by SaaS providers. The level is complicated by the size of the operation and the industry serviced. 

• Rules on data privacy: In most countries, including the European General Data Protection Regulation (GDPR) and the United States Health Insurance Portability and Accountability Act (HIPAA), there are laws that require strict isolation and protection of information. An effective, logically segregated multi-tenant architecture should be provided by the provider to address these standards. In the case of very sensitive data, this may require a hybrid model or a single tenant environment to ensure the desired amount of isolation and control.
• Dealing with tenant specific customizations: Multi-tenancy has a tradeoff on standardization to achieve efficiency versus the needs of individual tenants. Although the main functionality of the application may be similar, tenants may need special branding, workflows, or data fields. An appropriately architectured SaaS platform offers configuration and personalization features without need of any alteration in the underlying, shared codebase as this would translate to maintenance that cannot be managed.
• Performance optimization: A noisy neighbor issue arises when a tenant of high usage utilizes an inappropriate portion of shared resources, thus decreasing the performance of the other tenants. The possible solutions are effective monitoring, resource capping, and strategic scale of infrastructure to maintain a constant performance of all tenants. 

Examples of SaaS tenants in the real world.

There are numerous flourishing SaaS enterprises that have perfected the art of tenant management so as to expand their operations.

• Salesforce: Salesforce being the pioneer of multi-tenancy designed its platform in such a way that it could easily serve thousands of tenants using the same infrastructure. Every customer, be it a small business or a large company, is an isolated customer with data. Metadata is used to manage customizations and customizations are managed as configuration information, and not as code modifications, which allows them to be updated quickly and on a platform wide basis.
• Microsoft 365: Enterprise customers Enterprise customers are tenants of the Microsoft 365 service. This tenant contains the information of the company and user accounts. One can manage their own users, groups and permissions with this model and enjoy the economy of scale of a large shared infrastructure.
• AWS tenant isolation: Cloud service providers such as Amazon Web Services (AWS) provide basic services that allow powerful multi-tenancy. As an example, container-based isolation with services such as AWS Fargate can provide individual, isolated, containerized environments on a shared infrastructure to each tenant. This provides greater security and still retains the aspect of scalability that multi-tenancy has. 

Conclusion

To build and scale effective SaaS applications, it is important to comprehend the complexity of SaaS tenancy, starting with the fundamental terminology, and management issues. This is because either through a multi-tenant mode which is less expensive and has more scalability or a single tenant which has the most isolation and control, your architectural implementation will greatly influence the performance and security of your product as well as its market position.

We would like to encourage you to read our strategy papers on SaaS to learn more and create strong and scalable applications that can address the requirements of the contemporary business environment.