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Legacy Application Modernization: Your Five-Minute Guide

Old systems built with the technology of the past are no longer relevant to modern business needs
May 31, 2024

Legacy applications are software programs that have been operational for a very long time—some date back even a century. They are the mainstay of business operations, but they are also difficult and costly to maintain. For organizations to remain competitive, their legacy applications must be modernized. This is achieved by replacing or rebuilding the old systems with new platforms, languages, and architectural styles.

Modernizing legacy applications is difficult. It requires a well-thought-out plan that covers an organization's human, process, and technology aspects. This article provides a step-by-step approach to launching your legacy modernization project.

Step 1: Strengthen the Business Case

Before investing time and money into legacy application modernization services, you need to create a case that is robust enough. Key elements include:

Identify Business Drivers

What business challenges are your business organization facing that can be resolved by the modernization of legacy systems? Common drivers include:

  • Agility is becoming the fundamental requirement to bring new products/services to the market.
  • Stagnation of hiring experts for obsolete languages
  • Rising maintenance costs
  • Lack of scalability or flexibility

Set Target Objectives

Describe what the exact goals are you want to manage from a modernization attempt. For example:

  • Save 30% of the IT maintenance expenditure.
  • Enable a mobile channel for business information.
  • Slash time-to-market of new features to 50% of the original time.

Detail Benefits

Enumerate the expected business benefits that would be created based on factors like cost, revenue, customer experience, and risk. This helps to also earn support from the key stakeholders.

Step 2: Assess Existing Systems

Once you have a solid business case, conduct a comprehensive assessment of your current application landscape. Key assessment areas include:

Inventory Systems

Catalog all systems, interfaces, and databases. Capture information such as the technology stack, data models, and integration points.

Map Dependencies

Diagram system components and data dependencies to identify risk areas. A legacy change or outage can ripple across connected systems.

Evaluate Functionality

Review system functionality against current and future business requirements. Identify functional gaps.

Analyze Code Quality

Examine code complexity, technical debt, and documentation. This impacts the effort required to modernize.

Assign Priority

With assessment data, assign modernization priority levels to each application based on business value.

Step 3: Determine Modernization Strategy

Next, analyze assessment findings to determine the right modernization strategy for each legacy app. Common strategic options:

  1. Replatform. Lift and shift the application to a new infrastructure/platform, like the cloud. This reduces hardware costs.
  2. Refactor. Keep the existing platform but refactor code, data structures, and UX/UI design. This increases maintainability.
  3. Rebuild. Fully redevelop applications using the latest technologies and modular architecture. This approach offers the highest business agility but is also the most expensive.
  4. Replace. Swap legacy systems for a commercial off-the-shelf (COTS) or software-as-a-service (SaaS) alternative. This is quicker to deploy but may require process change.
  5. Retain. Keep investing minimal enhancements into stable, non-critical legacy systems. This is the lowest disruption.

Evaluate total cost, risk, and business impact when selecting strategies. Hybrid approaches are common across a legacy portfolio.

Step 4: Plan the Migration

With legacy systems earmarked for modernization, it’s time to plan the migration:

Architect Target State

Define target architecture vision across infrastructure, data, integrations, UX, and modular services.

Staff Accordingly

Build out cross-functional teams combining both legacy domain experts and technical modernization resources.

Choose Transition Approach

Select transition methodology - big bang single cutover, phased rollout by region/users, or parallel run.

Mitigate Risks

Identity risks around areas like data integrity, security, ops availability, and user adoption. Create mitigation plans.

Budget & Schedule

Estimate efforts, build a project plan, and secure appropriate funding for the modernization program.

Step 5: Execute Migration

With a solid migration plan in place, now tackle executing the complex task of transitioning from legacy to modern:

Digitalize Processes

Rethink and optimize business processes first before translating them into digital systems.

Mobilize Change Network

Engage with business and IT stakeholders early and often to manage change.

Integrate New Capabilities

Utilize API-led connectivity to weave in modernized components into the existing environment.

Test Iteratively

Validate frequently - functionality, integrations, user scenarios and performance. Fix issues quickly.

Decommission Legacy

Once the modern version is stable, retire legacy applications and infrastructure.

Step 6: Continue Optimizations

Legacy modernization is not a one-time affair. The new modern landscape is a dynamic environment that needs continuous investments and refinements.

  • Expand Features. Implement agile techniques to constantly deliver improvements that meet ever-changing business expectations.
  • Refine Architecture. Evolve the architecture using the latest technologies and cloud services. Use COTS solution instead of custom code.
  • Upgrade Skills. Refresh staff with modern skills including cloud, DevOps, and user experience design.
  • Clean Technical Debt. Actively deal with the technical debt that has accumulated by paying off defects, increasing test coverage, and deleting outdated codes.
  • Consolidate Systems. Identify areas to merge systems that perform similar jobs to bring down expenses.

By adhering to these instructions, organizations will be able to make their legacy systems that are outdated into modern and agile technology platforms that are delivering more value to the business. The journey involves a lot of patience to minimize the disruptions, however, the long-term benefits are great and worth the cost and investment.

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