Welcome!

Agile Computing Authors: William Schmarzo, Elizabeth White, Pat Romanski, Zakia Bouachraoui, Liz McMillan

Related Topics: Agile Computing, Containers Expo Blog, @CloudExpo

Agile Computing: Article

Architecting for Multi-Tenancy in the Cloud

Implementing a multi-tenant service

Why is Software as a service (SaaS) gaining such momentum? What makes the SaaS proposition so compelling? “Faster time to capability” and “lower upfront cost” are two of the main reasons for this. For any organization looking into adding a system capability, once the buy or build decision is out of the way and the decision is to buy, there are two choices; either buy a software package and deploy it on premise OR subscribe to a SaaS provider. Deploying a software package on premise is no simple task. It can take months or even years to go-live with full functionality and realize the ROI. In contrast, SaaS can provide full functionality in days to weeks.

The reason SaaS can provide such fast time to capability and low upfront costs is because of a shared service model where multiple customers share the same deployment of software. This is also known as multi-tenancy. Achieving multi-tenancy is not trivial and requires a lot of upfront thinking and architectural work. The complexity due to multi-tenancy can vary depending on the nature of the service. For example, in the case of an infrastructural service (such as email, instant messaging etc), all customers (tenants) would pretty much require the same set of functionality. In contrast, a business application service (such as salesforce automation) might have to support different business processes, policies and rules for different customers (tenants), which can make the service very complex and challenging to implement. Also, usually, implementing multi-tenancy in business to consumer (B2C) services is simpler than that in business to business (B2B) services, because B2C services are used directly by customers of the service whereas B2B services are used by end-users of customers, leading to an additional layer of complexity to manage. Further, implementing multi-tenancy for Platform as a Service (PaaS), what I like to call multi-tiered multi-tenancy such as the Force.com platform is even more complex. Here each tenant has multiple tenants in turn and each of these tenants might need their own extensions or modifications to the functionality!

So how is multi-tenancy achieved? A typical software application consists of an application tier and a database tier. Different strategies can be applied at application and database tier to support multi-tenancy.

The simplest approach to implementing multi-tenancy is to create completely separate instances of servers (application and database) for each tenant. With this approach, application code and database schema for each tenant are deployed on completely separate servers and there is no sharing across tenants except the common codebase and schema definition. Each tenant can potentially have its own extension of the code and database schema to support any difference in processes and functionality from other tenants, although it can get very costly to maintain tenant specific extensions. With this approach, even though codebase is shared across multiple tenants, the cost of deployment for each tenant can be pretty high which in turn will increase the cost of the service. One way to optimize the cost with this approach is to host multiple instances of application and database servers on the same hardware. This can be further optimized using server virtualization. This may be an acceptable approach if the number of tenants is expected to be very small.

A more optimal way of implementing a multi-tenant SaaS (or PaaS) solution is to deploy shared instances of servers across multiple tenants. This is where SaaS starts to pay off. With this approach, compute and storage resources are shared across multiple tenants resulting in lower cost of service for each tenant. Within this approach, multiple levels of sharing can be implemented to further reduce the cost of the service as follows:

  • Instance sharing: Instance sharing can be done, 1) only at the database server level or 2) both at application and database server level. Of course, more sharing means more savings which can be passed on to customers resulting in lower cost of service. But more sharing also means that more upfront thought has to go into architecture and design of the service since any problem with the shared instance will affect multiple tenants. This higher upfront investment can have a huge long-term payoff though by reducing the operational cost (and hence total cost of ownership) of the service.
  • Database schema sharing: If instance sharing is implemented at the database level, then within the same database server instance, 1) a separate database user schema can be deployed for each tenant or 2) all tenants can share a common database user schema. Common database schema is more cost effective but can be challenging to implement and optimize. Handling custom extensions for each tenant can make this even harder to implement. One way to deal with this is to drive functionality based on meta-data. Each tenant can inherit the common meta-data and define its own meta-data on top of that to support tenant specific extensions to processes and policies. This is how Salesforce.com is designed. Database partitioning strategies can be implemented for better performance. Data is usually partitioned based on customer ID (Tenant ID) to keep all the data for a given customer in the same partition for performance reasons. A certain number of predetermined tenants live in each partition. The extent to which tenant specific extensions need to be supported depends on the nature of the service as mentioned earlier (e.g. email vs sales force automation)
  • Application code sharing: If instance sharing is implemented at the application server level, then within the same application server instance, 1) separate code modules can be deployed for each tenant or 2) all tenants can share the same code module deployment (e.g. war file). Again, more sharing means more savings but the operational issues have to be kept in mind and lot of thought has to go into architecture and design of the shared application. All the rules should be externalized so that tenant specific extensions to processes and policies can be incorporated in the shared codebase. Application partitioning strategies can be implemented to improve performance and scalability of shared applications. Multiple partitions can be created to support large sets of tenants. Requests can be routed to the correct partition based on tenant ID and/or other predetermined criteria.

In conclusion, there are multiple ways to implement multi-tenancy and the choice depends on the nature of service being implemented. It is very important to spend the necessary time upfront during architecture phase to determine the multi-tenancy needs and to come up with the best design for supporting multi-tenancy, depending on the current needs and future vision of the service. Once the approach has been decided and implemented, it can be extremely difficult and costly to change, much like converting a fourplex into a multiplex apartment complex can be an almost impossible task without starting from scratch.

More Stories By Vinay Singla

Vinay Singla is a senior technology professional with extensive experience in the SaaS and SOA space.

IoT & Smart Cities Stories
Darktrace is the world's leading AI company for cyber security. Created by mathematicians from the University of Cambridge, Darktrace's Enterprise Immune System is the first non-consumer application of machine learning to work at scale, across all network types, from physical, virtualized, and cloud, through to IoT and industrial control systems. Installed as a self-configuring cyber defense platform, Darktrace continuously learns what is ‘normal' for all devices and users, updating its understa...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
CloudEXPO has been the M&A capital for Cloud companies for more than a decade with memorable acquisition news stories which came out of CloudEXPO expo floor. DevOpsSUMMIT New York faculty member Greg Bledsoe shared his views on IBM's Red Hat acquisition live from NASDAQ floor. Acquisition news was announced during CloudEXPO New York which took place November 12-13, 2019 in New York City.
OpsRamp is an enterprise IT operation platform provided by US-based OpsRamp, Inc. It provides SaaS services through support for increasingly complex cloud and hybrid computing environments from system operation to service management. The OpsRamp platform is a SaaS-based, multi-tenant solution that enables enterprise IT organizations and cloud service providers like JBS the flexibility and control they need to manage and monitor today's hybrid, multi-cloud infrastructure, applications, and wor...
The Master of Science in Artificial Intelligence (MSAI) provides a comprehensive framework of theory and practice in the emerging field of AI. The program delivers the foundational knowledge needed to explore both key contextual areas and complex technical applications of AI systems. Curriculum incorporates elements of data science, robotics, and machine learning-enabling you to pursue a holistic and interdisciplinary course of study while preparing for a position in AI research, operations, ...
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
Tapping into blockchain revolution early enough translates into a substantial business competitiveness advantage. Codete comprehensively develops custom, blockchain-based business solutions, founded on the most advanced cryptographic innovations, and striking a balance point between complexity of the technologies used in quickly-changing stack building, business impact, and cost-effectiveness. Codete researches and provides business consultancy in the field of single most thrilling innovative te...
Atmosera delivers modern cloud services that maximize the advantages of cloud-based infrastructures. Offering private, hybrid, and public cloud solutions, Atmosera works closely with customers to engineer, deploy, and operate cloud architectures with advanced services that deliver strategic business outcomes. Atmosera's expertise simplifies the process of cloud transformation and our 20+ years of experience managing complex IT environments provides our customers with the confidence and trust tha...
With the introduction of IoT and Smart Living in every aspect of our lives, one question has become relevant: What are the security implications? To answer this, first we have to look and explore the security models of the technologies that IoT is founded upon. In his session at @ThingsExpo, Nevi Kaja, a Research Engineer at Ford Motor Company, discussed some of the security challenges of the IoT infrastructure and related how these aspects impact Smart Living. The material was delivered interac...
Intel is an American multinational corporation and technology company headquartered in Santa Clara, California, in the Silicon Valley. It is the world's second largest and second highest valued semiconductor chip maker based on revenue after being overtaken by Samsung, and is the inventor of the x86 series of microprocessors, the processors found in most personal computers (PCs). Intel supplies processors for computer system manufacturers such as Apple, Lenovo, HP, and Dell. Intel also manufactu...