| Architecture Style |
Single, unified codebase for the entire application. |
Decoupled services, typically using an Enterprise Service Bus (ESB) for communication. |
Independent, small services that communicate via lightweight protocols like HTTP/REST. |
| Size and Complexity |
Large, tightly coupled application. |
Modular but often larger services compared to microservices. |
Fine-grained, small, loosely coupled services. |
| Communication |
Internal method calls within the same process. |
Typically uses ESB for messaging and service coordination. |
Communicates via lightweight mechanisms such as REST or messaging queues. |
| Deployment |
Entire application must be redeployed for changes. |
Individual services can be deployed independently, but ESB may require coordination. |
Independent services can be deployed and scaled independently. |
| Scalability |
Limited scalability; scaling involves duplicating the whole application. |
Scalable, but can be bottlenecked by ESB. |
Highly scalable; individual services can be scaled based on demand. |
| Maintenance |
Harder to maintain; any change may affect the entire application. |
Easier to maintain due to modularity but complexity in ESB management. |
Easier to maintain as services are smaller and focused on specific tasks. |
| Fault Isolation |
Failure in one part can bring down the entire system. |
Better fault isolation but complex ESB can affect recovery. |
Failures are isolated to specific services; the rest of the system remains unaffected. |
| Data Management |
Centralized database shared by the entire application. |
Shared databases but with some service-specific schemas. |
Each service manages its own database, promoting data isolation. |
| Performance |
Faster within a single process, but can become slow as the application grows. |
Slower due to ESB overhead and service orchestration. |
Can be slower due to network communication, but scales well under load. |
| Pros |
Simple to develop and deploy in small applications. |
Modular services, better reusability, flexibility with ESB integration. |
Highly scalable, fault-tolerant, technology agnostic, and easy to maintain. |
| Cons |
Difficult to scale, maintain, and deploy in large systems; tightly coupled components. |
ESB can become a bottleneck; increased complexity in managing service dependencies. |
More complex to develop due to distributed nature; requires good management of service communication and data consistency. |
