SaaS Developer Guide - Part 1 - The Basics from SaaS Providers POV

This is the first blog post of a series, that is going to explain concepts and guide lines on how to build a successful SaaS application to deliver your services over the cloud. It aims to present the concepts and then dig deep into technical nitty-gritty behind SaaS concepts such as auto-scaling, resilience, user-experience, economy of scale and etc... All blog posts can be found under the tag SaaS Developer Guide

Cloud providers have spoiled the current SaaS consumer market with cool features. There are lot techniques and technologies, that are used to deliver SaaS as it has become a very mature form of software delivery.  Each day we hear SaaS providers delivering awesome user experience, and the question is how would you meet their sky-rocketing expectations?  Firstly, as a SaaS provider, it is important to have a deep understanding of SaaS characteristics, because it leads to best architectural principles, design patterns, implementation and deployment practices. 

SaaS characteristics,

• The software is centrally hosted by the vendor

• Provides self-service mode of operation

• License is subscription based, and supports "pay-as-you-go" model

The software is centrally hosted by the vendor

SaaS software needs to be designed such that it can serve thousands of concurrent users. Use access it via browser over the Internet. It must have properties such as,

• Highly Scalable - Modern software depends on horizontal scalability, i.e. software is designed as a distributed system or as a set of distributed services. In a distributed system the services coordinate over a network by passing messages to achieve a common task. This brings the advantage of ability to maintain each service independently from other parts of the system, allowing continuous delivery and controlled upgrades. Each service is cohesive and stateless,  allowing the system to be rapidly scaled up and down as desired.

• Resilient - SaaS needs should have self-healing fault tolerant features as it is deployed on an IaaS layer most of the time. If an instance goes down, there must be measures to bring up another instance automatically. If an instance is malfunctioning, that needs to be identified quickly and removed from the distributed system.

• Optimized resource consumption - In order to optimize the usage of IaaS by the SaaS, it needs to be dynamically scalable. As the demand goes high the system should scale up and when the demand goes down it should scale down. Lazy loading of containers and tenants is another approach of minimizing the IaaS layer consumption. In short terms this is called the "economy of scale". This means how many users the application will serve using X number of resources. This is a broad area that starts with  the architectural level decisions such as "container-zing" vs "multi-tenancy" and goes all the way down to coding, caching data, CDN networks to browser caching.

• Security - Security is another major area that a SaaS provider needs to be concerned about. This includes security of the data as well as the perimeter security. Data needs to be backed-up regularly and only authorized parties must have access to the data. APIs are to be protected and proper perimeter security must be in-place

Provides self-service mode of operation

SaaS is a user-facing software and needs to be maximally UX engineered. User stories must be written and tested. User behavior can be recorded (by recording user clicks) and analyzed to identify gaps. UX all the way is very important. Some of the characteristics of self-service mode of operation are,

• Self-registration - Users register organizations and users

• Password resetting, user/profile management, authorizations

• Subscription management 

• Monitoring their usage and rates

• Ability to monitor business activity

• Provide certain degree of customization

• Configurable dashboards 

License is subscription based, and supports "pay-as-you-go" model

Monitoring usage and metering is the key to support subscription based model of payments. Users pay per use and different bands of usages are available. When it comes to "pay per use", usage needs to be monitored at granular level. Each metering attributed needs to be recorded so that it is counted in the billing process. Recording the actions of thousands of users is a challenging task because of the volumes. Further the recorded data needs to be summarized periodically to execute throttling on usage and to generate the monthly bill/overages. There are well established architectural and design patterns that allow SaaS applications to handle large data volumes and generate billing information.