The advent of the second decade of the 21st century has seen businesses leaning towards coworking spaces. Operating in space shared by professionals who help each other grow seems to be a beneficial idea. What is more, it is quite logical from the financial point of view, as it is lighter on one’s pocket. Renting a hot desk for a needed amount of time, instead of paying a monthly rate for a full-fledged office is way cheaper and efficient in terms of economized time and resources. While the tech, financial, and real estate industries are nowadays tightly intervened, it didn’t take long before the concept of sharing the space has infiltrated the IT-market. Nonetheless, developers know it by the name multitenancy, which is quite an interesting concept to discuss, especially if your company tends to provide similar software development and support services to a range of customers. Before we plunge ourselves into the whirl of technicalities, let us first define what the concept of multitenancy actually is. Multitenancy is an architectural approach that lets multiple independent instances of copious or single applications operate jointly in a shared environment. Sounds a bit of rocket science, right? Yet, multitenancy is nothing to be afraid of even if you hear the term for the first time. Long story short, multitenancy is an approach that lets you build an app to be used by copious customers at the same time. Nonetheless, while multitenancy is built on the principle of using a common database, each of your customers can have their own secure database that does not intervene with the other cloud repositories within the same space. It all depends on the variant of a multitenant architecture that they would like to have in the product. Multitenancy is quite a bilateral concept that gets both positive and negative reviews from developers. So, let’s shed the light of truth on what a multitenant approach in app development is and what are the best situations to use it. 

Is It That Good? 

 Before we take to discussing the modes and ways of using multitenancy, let us first deal with the probable counter-arguments that might be coming from the folks that disapprove of its usage.  Copious developers still doubt the efficiency of a multitenant approach, claiming that it might add noise and complexity to the development process. While the multitenant instances are becoming more and more omnipresent within the modern applications’ stack, a multi-cloud strategy, which is the core of the multitenancy approach, represents an unprecedented challenge to legacy analytics. Imagine your company taking over a development project that requires a couple of new instances added. The critics claim that you will have to face an immense tech debt that will surely make your project stagger along the way. Instead of working on the features required, you will have to deal with a lot of research pertaining to the platform's stack. Thus, a developer will require an enhanced intelligence strategy in order to deal with the data consolidated within the single pane created throughout developing a multitenant app. Still, it should be acknowledged that the majority of multitenant apps are built from scratch, which means that the so-called noise and complexity are not that much of a problem. 

Django (Un)Chained? 

 Django framework, which is the core platform for developing multitenant apps, is also being harshly criticized by today’s critics for being too slow. This Python-based open-source web framework is known as being a widely used 501 non-profit module that is built on the model-template-view architecture pattern. Nonetheless, it lacks convention, when compared to, for example, Ruby on Rails. As a result, the configuration panel is too extensive and ends up slowing the development process down. Django is also not the best choice for you if you are looking to develop a lot of small projects hosted on a multitenant cloud. It might be too complicated for developing copious and simplistic projects, given the expansive toolkit it features. However, analyzing an app’s legacy and tech debt is a hard task regardless of the web framework used. Therefore, claiming that opting for a multitenant approach might be a mistake because of the noise and complexity seems to be quite a vague statement. What is more, the Python ecosystem depends heavily on the internal configurations, so it does not matter whether you use Django. Even though Django might seem too monolithic and requires a developer’s comprehensive knowledge of the system, it is easy to integrate with another Django app, and it offers a lot of routes to follow when developing a multitenant application. There are multiple schemas to use when building a multitenant app, even when there is a single database. 

Multitenant Equals Multipurpose

 A multitenant app is nothing but a bunch of logically isolated and physically integrated instances, that is, tenants. One of the most widespread causative factors for using the multitenant approach is saving money. You don’t have to develop the same feature for each and every customer, while you can simply keep adding instances to an already existing app. A resource saved is a resource earned. This is one of the most widespread programming architectures in cloud computing, with Lambda, a serverless technology from AWS being a vivid example of how multitenancy can be a truly reasonable from the financial point of view decision. Frankly speaking, multitenancy is also something that the IT companies’ customers enjoy a lot.   One business can come and buy an instant application and spare itself of waiting for the product to be developed. Meanwhile, the developers themselves, depending on the contract they sign with the customer, can resell the app’s features to other businesses as there is still enough place for the clients to join the party. While the app is hosted in one space, it can be used by multiple users. Sometimes, it might not be the best approach, especially for the companies that require all the information to be stored on their own services. Nonetheless, the advantages offered by multitenancy are quite obvious to perceive. The app is easier to support and manage, and it takes less resources to deal with it. What is more, the information-sharing capacity is being boosted, as the tenants can embark upon mutually-advantageous information exchange. Finally, those who keep claiming that multitenancy is not secure should know that each and every tenant can have its own private space within the server. 

Multitenancy Modes

 As a matter of fact, there are three modes of implementing multitenant apps, as the correlation of instances and databases can always be gauged in accordance with the needs of the project. 
  • Mode 1. Multiple Database Instances.
This mode is being applied when you have a lot of tenants with separate databases. However, keeping each tenant’s data private can be more expensive. 
  • Mode 2. Single Database with a Single Usage Schema.
This is the primordial multitenancy approach. It is the cheapest to apply as it requires almost no additional developmental moves. Yet, it is associated with lower performance due to the server overload. 
  • Mode 3. Single Database and Multiple Schema.
This is the most advanced multitenancy mode, as it envisages the usage of a unified database while keeping the users’ data secure and costs redacted. While performance might also drop down a bit, it is still the best multitenancy approach, as here, the tenants’ information is stored individually. A new tenant means a new schema, and there is no need to add any further configurations. The information that the tenants decide to share is stored in the public schema. The biggest advantage of multitenancy experienced by developers is the Do Not Repeat yourself principle. You don’t have to do the same job for every customer. Nonetheless, it yet takes some time to copy the general features and add the new ones when the new instances, tenants come, as multitenancy is also dependent on the Repeat Yourself or Die principle. 

When To Use It 

 The multitenant approach is quite a useful thing to know and use in three pivotal cases. As a developer, you know that it all depends on your customers' specific needs, but here comes a short and yet comprehensive description of the practical situations in which building a multitenant app might be your best solution. 
  1. Building a multi-tier system that requires a unified database. It might be useful when your client is a big corporation asking for developing a unique database for a number of its affiliated companies. A great example of a multi-tier system with a unified database is SAP ERP - a resource planning tool used by companies worldwide. It is composed of a database backend and several web servers. Adding new customers is not a problem, as everything to be done in such a case is to add a new instance.
  1. Your customer approaches you and asks to build a system that envisages several simultaneous processes running. For example, a bunch of web services open to different customers via a range of domain names. However, the processes running on the server have to be the same. Here, you should apply the multitenant approach and isolate the data by establishing several databases. This is multitenancy as pure as it comes. A nice example of simultaneous processes running on various databases is the SQL server that holds copious processes for a host of users with isolated information.
  1. Applying the multitenant approach would also be a great decision when you need to establish a system that can simultaneously and similarly run a couple of loosely connected sets of web services with separate micro-databases. Coding a register feature for them will help; you would be able to start new clones of the microservices, which will be automatically looking for their peers and would connect to them automatically, thus offering a unified application behavior.
 When developing a multitenant app of such a type, you, as a developer, face two scenarios. When the app or a new instance is created for serving a new customer, this is a new set of microservices that must be established. Furthermore, they must be organized in a manner to connect solely to the operations related to one customer. Thus, you end up with a number of single tenants within the app. However, running the same code for copious customers while keeping their information logically separated means creating a pure multitenant app. 

It’s Good When It’s Apropos

 The concept of multitenancy is nothing but a reference to the mode of software operation that envisages multiple stances coming from one or more applications operating in a shared environment. While the tenants represent the instances, that is, clients using the app, a developer gets rid of a myriad of tasks and saves a lot of money. Sure enough, multitenancy is not a universal app building approach to use. Still, it surely offers many benefits when it comes to dealing with copious customers that require similar features.