Many companies depend on legacy systems: old applications developed years (or decades) ago that remain critical to the business. Although they work, they are increasingly difficult to maintain, integrate, and evolve. Is it time to migrate? We help you decide.
What is a Legacy System?
A legacy system is any application that:
- Uses obsolete or hard-to-maintain technologies
- Doesn't easily integrate with modern systems
- Depends on knowledge concentrated in few people
- Has high maintenance cost relative to its value
- Cannot evolve at the pace the business needs
Common examples: Visual Basic applications, Access, Delphi, old client-server systems, custom ERPs from the 90s or 2000s.
Signs You Need to Migrate
Technical Signs
- Unsupported technology: The language or framework no longer receives security updates
- Integration problems: Can't connect with modern APIs or cloud services
- Degraded performance: The system is slow and doesn't scale
- Non-existent documentation: Nobody knows exactly what the code does
- Specific hardware dependency: Requires old servers or OS
Business Signs
- Growing maintenance cost: Each fix is more expensive than the last
- Staff risk: Only one or two people understand the system
- Missed opportunities: Can't implement features the business needs
- Competition advancing: Your competitors offer better digital experiences
Migration Strategies
1. Big Bang (Complete Replacement)
Develop a new system from scratch and migrate everything at once.
- Pros: Clean system without inherited technical debt
- Cons: High risk, long project, possible business interruption
- When to use: Small systems or when legacy is irreparable
2. Strangler Fig (Gradual Strangulation)
Build the new system around the legacy, progressively replacing functionalities.
- Pros: Lower risk, incremental value deliveries
- Cons: Period of coexistence of two systems
- When to use: Large systems where you can't stop the business
3. Lift and Shift
Move the system as-is to modern infrastructure (cloud) without changing code.
- Pros: Fast, lower initial investment
- Cons: Doesn't solve architecture or technology problems
- When to use: As a preliminary step to a deeper migration
4. Progressive Refactoring
Modernize existing code module by module.
- Pros: Preserves existing investment, low risk
- Cons: Limited if base architecture is bad
- When to use: When system has good base but obsolete technology
Steps for a Successful Migration
1. Analysis and Documentation
Before touching code, document:
- All business processes the system supports
- Integrations with other systems
- Data: structure, volume, business rules
- Users and their workflows
2. Define Priorities
Not everything is equally critical. Classify functionalities:
- Critical: Business doesn't function without them
- Important: Provide significant value
- Desirable: Nice to have
- Obsolete: No longer used, eliminate
3. Data Migration
Data is the most valuable asset. Migration plan:
- Source to destination data mapping
- Cleaning and normalization
- Tested migration scripts
- Rollback plan
4. Exhaustive Testing
The new system must do at least everything the previous one did:
- Functional tests by business process
- Regression tests
- Validation with real users
- Load and performance tests
5. Training and Change
A new system requires adaptation:
- User training
- Updated documentation
- Intensive support in the first weeks
- Feedback channel for improvements
Benefits of Migrating to Web with Symfony
- Access from anywhere: You only need a browser
- Modern integration: REST APIs to connect with any system
- Scalability: Grows with your business
- Simple maintenance: Centralized updates
- Current security: Framework with active support
- Available talent: It's easier to find Symfony developers than COBOL
Conclusion
Migrating a legacy system is a complex but necessary project for many companies. The key is to plan well, choose the right strategy, and execute incrementally to minimize risks.
Have a legacy system holding you back? Contact us to evaluate modernization options.