There is widespread adoption of microservices architecture by enterprises in recent times. It is driven by the promise of improvements in resilience, scalability, time to market, and maintenance, among other reasons. In this post, we chalk out a plan for how organizations that wish to migrate existing applications to microservices can do so safely and effectively.
In a typical monolithic application, all the data objects and actions are handled by a single, tightly knit codebase. Data is typically stored in single database or filesystem. Functions and methods are developed to access the data directly from this storage mechanism, and all business logic is contained within the server codebase and the client application. It is possible to migrate several monolithic applications and/or platforms. Each module will have its own data storage mechanisms, user interfaces, and data schema, into a unified set of microservices that perform the same functions as the original applications under a single user interface.
Migrating these applications to microservices offers the following advantages:
- Removing duplication of effort for manual entry
- Reducing programmatic development risks
- Providing a single, unified view of the data
- Improving the control and synchronization of these systems
Migrating from Monolith to Microservices
Scalability is one of the primary motivations for moving to a microservice architecture. Components that are used by the most users should be considered for migration first.
Users want their interactions with a system to return the right data at the right level of detail, usually as fast as that data can be acquired. The jobs for users each involve one or more data objects, and each data object has a set of associated actions that can be performed. The development team that designs and implements the system must consider the collection of jobs, data objects, and data actions. A typical process to migrate from a monolithic system to a microservices-based system involves the following steps:
- Identify logical components.
- Flatten and refactor components.
- Identify component dependencies.
- Identify component groups.
- Create an API for remote user interface.
- Migrate component groups to macroservices (move component groups to separate projects and make separate deployments).
- Migrate macroservices to microservices.
- Repeat steps 6-7 until complete.
Step 8 exists because development team need not perform the entire migration at once. They can pull components out of the legacy monolith and make them into microservices, either singly or in groups as the development warrants.
1. Identify logical components:
When combining multiple systems into a unified system, the data objects, data actions, and jobs to perform for each individual system must be identified. All these components are implemented as modules within the codebase with one or more modules representing each data object, data action, and job to perform. These modules should be grouped into categories for working with later steps.
2. Flatten and Refactor Components:
After all the modules have been uniquely identified and grouped, it is time to organize the groups internally. Components that duplicate functionality must be addressed before implementing the microservice.
In the final system, there should be only one microservice that performs any specific function. It is essential that one final representation exists for each unique datatype.
3. Identify Component Dependencies:
After the components have been identified and reorganized to prepare for the migration, the system architect should identify the dependencies between the components.
It can be performed using a static analysis of the source code to search for calls between different libraries and datatypes. Another method can be to use dynamic analysis tools to provide an automated map between components.
4. Identify Component Groups:
After the dependencies have been identified, the system architect should focus on grouping the components into cohesive groups that can be transformed into microservices. The goal is to identify a small set of objects and their constituent actions that should be logically separated in the final system.
5. Create an API for Remote User Interface:
The remote user interface is intended as the sole mode of communication between the system, its components, and the system’s users. It is vitally important that this interface be scalable and well planned to avoid problems as the system evolves over time. The underlying interface must be usable both during the migration and afterwards.
6. Migrate Component Groups to Macroservices:
It is an interim step toward migrating to full microservices. The reason for not moving directly to microservices is complexity. A monolithic system is typically built with intertwined logic that may cause problems when converting to microservices. If the monolith is continuously changing, then migrating to microservices in a single step will be a continuously changing target as well.
The key goal at this step is to move component groups into separate projects and make separate deployments. At a minimum, each macroservice should be independently deployable from within the system’s continuous integration (CI) and continuous deployment (CD) pipeline.
7. Migrate Macroservices to Microservices:
In this step we pull the components, data objects, and functions out of the monolithic system and into macroservices, and can be further separated into microservices.
8. Deployment and Testing:
Once a macroservice or microservice is ready for deployment, the next step involves integration testing and deployment.
Wrapping Up
This plan is for migrating existing applications to microservices. It is intended to enable organizations to realize benefits of microservice architectures, such as resilience, improved time to market, and easier maintenance, with minimal disruption to existing applications and services.
You can also hire a trusted integration solution provider to assist you with migration to microservices architecture for your applications. The remote team has expertise in implementing microservices for enterprise applications.