Today, most enterprises trust their age-old legacy applications to support their business-critical systems. However, several critical concerns, as maintainability and scalability issues, are associated with the legacy system.
Cloud services offer a more agile and cost-effective platform to support business applications and IT infrastructure in this background. Moreover, as the adoption of cloud services has been increasing recently, so has the cloudification of mobile apps.
Cloudification is moving services or applications from on-premises to the cloud. Every organization is planning to move its maximum applications to the cloud. There are many benefits to going to the cloud.
Benefits of Cloudification for the Organizations
- Flexibility to Scale Up or Down
- Disaster recovery
- No upfront cost for Hardware & Software Licenses
- Focus on Core Business
Cloud Service Models
- IaaS (Infrastructure as a Service)- A virtualized environment on which systems can be deployed. This provides the underlying computing resources for the deployment of enterprise systems.
- PaaS (Platform as a Service)- We call it "Cloud Platform Services." What developers gain with PaaS is a framework they can build upon to develop or customize applications. In addition, PaaS makes the development, testing, and deployment of applications quick, simple, and cost-effective.
- SaaS (Software as a Service)- Cloud computing offering provides users with access to a vendor’s cloud-based software. Users don't need to install apps on their local devices. Instead, they reside on a remote cloud network accessed through the web or an API.
Below are a few key decision factors that help you to decide the best Cloud Service Model for your application & take further actions:
1. Integration with other on-premises applications- If your application has some integrations with other on-premises applications and you are not moving other applications to the cloud, then you need to also plan for Hybrid implementation so that after migration, your application (from the cloud) can communicate with on-prim applications securely. Many cloud providers provide a secure gateway or channel between on-prem and cloud.
2. Database compatibility on Cloud- First, check does particular cloud provider offers you a similar database on cloud PaaS. If yes, then go for it. If not, you can think of using another compatible database (of course, data migration will be overhead), or you can go for VM on IaaS & install your database and use it from PaaS applications.
3. Session Management- Scaling is one key feature of the Cloud. If you are planning to go on Cloud, then you should have stateless web applications or services. It will allow you to scale your application horizontally when user load increases. For example, if your application has some IN-Proc session, you can either save it to Database or Redis cache.
4. User-uploaded files or images- If your web application has provision for the user to upload images and documents on the web application and you are storing those on the application server itself, then you need to make changes in the application to store these files on separate storage, e.g., File Storage or Blob Storage. This will help your application to work properly when your applications multiple instances are running.
5. Dependency on any third-party software or custom software- If your application is dependent on any third-party software or application that needs to be installed on the application server, you need to check that particular Cloud service allows you to install these types of software. If not, you need to go for VM on IaaS to have full control over the application environment.
6. Dependency on Registry values- If your application depends on some particular values in the server's registry, you will not be able to use the Cloud PaaS service; you need to go for VM on IaaS.
7. The specific Port-If your application is dependent on a specific TCP port, then check the particular Cloud Service that allows you to communicate on that port. If not, then go for VM on IaaS.
8. Caching Implementation- If your application uses application caching to improve performance, it may become a bottleneck in the cloud where multiple instances of an application can be there. Therefore, you should have a separate caching mechanism or use PaaS Redis Cache.
9. User Authentication- If your application uses an on-premises Active Directory for user authentication, you need to think of a way to authenticate the user when your application is on Cloud. Either you can use some Cloud AD service (e.g., Azure AD) and sync on-prem users with Cloud AD or authenticate users by ADFS.
10. Cloud neutral development- If you don't want to stick with any particular cloud provider, you should go for the Container approach to move your containers from one cloud provider to another.
If you have complex business logic in the legacy application and many dependencies on other software's which you feel tough to migrate on PaaS, you can go for VM on IaaS as the first stage; this will give you upfront benefits, cost & maintainability.
Finally, check all the possible hurdles during application modernization to the cloud and do a proper cost-benefit analysis before starting a migration activity.