<img alt="" src="https://secure.cold5road.com/218968.png" style="display:none;"> Skip to main content

Migrating legacy systems can feel overwhelming. In this guide, we explore service-orientated architectures and why you may, or may not, want to use them.


Exploring Migrating Legacy Systems: Should you use Service-Oriented Architectures?

Posted by Angela Davis on March 5, 2024
Listen to audio version

Migrating legacy systems can feel overwhelming, especially as there are so many different technologies, systems, and methods that can be used as part of the process. However, legacy system migration is essential for keeping modern businesses competitive and avoiding reliance on outdated systems. 

In this article, we will explore the technology of service-orientated architectures (SOAs), a self-contained software unit designed to complete a specific task. We’ll dive deep into the benefits and potential drawbacks of SOAs as well as how they are used.

We’ll also take a look at how SOAs fit into the future of digital modernization and how OpenLegacy can offer you a simpler method for migrating legacy systems.  

A diagram illustrating service-oriented architecture (SAOs).

Image source

What are service-oriented architectures (SOAs)?

Service-oriented architectures were designed to help with the increasing demands made upon business systems. The software systems are built in segments called services that contain both the code and the data needed to perform a specific function. This means that each service is self-contained and reusable. 

SOAs were designed to focus on the unique needs of businesses and make systems more versatile and scalable. They are built with common interface standards so that they can communicate across different platforms and be easily incorporated into new applications. Because of this, SOAs are easier to deploy and use, improving performance and lowering maintenance costs.

The benefits of using SOAs

SOAs were designed to translate technologies into business services that would create more value for businesses. This means that they can be used as a method of legacy system modernization. Let’s explore the benefits of using SOAs in more detail.

Saves costs by reusing services

SOAs allow businesses to continue using their existing services and save money by reusing them or even transforming them into public assets. However, it’s important to note that integrating existing services into new architecture always requires careful handling.

There are scenarios in which existing services will fit more easily with new SOAs, for example, updated or migrated versions should be less complicated and leave essential functions accessible and usable. 

Continuous system scalability 

As digital transformation continues to accelerate and data amounts increase, systems always need to be delivering more. SOA offers continuous scalability to allow systems to grow in line with increasing demands.

If a service isn’t coping with demand, it can be replicated and more instances of it can be created, allowing businesses to easily meet changing needs.

In comparison, legacy systems often cannot scale without damaging cache efficiency. 

Independent loose coupling

One of the most important advantages of SOA systems is their loose coupling. Legacy architecture uses interconnected modules and tight coupling. However, SOA provides the ability to implement loose coupling and gain independence from many technologies. 

This flexibility means that developers can add new features to existing services instead of creating them from scratch. This can reduce development time, increase productivity, and cut costs. 

Lucrative structuring

With an SOA system, business layers are organized and structured in a methodical and logical way to allow rapid responses to challenges or changes in either business or technical areas of your organization.

If a component isn’t working the way you want or need it to, then SOA makes it easy to either remove or replace it, without adversely affecting your whole system, simplifying and accelerating maintenance to large applications. 

Drawbacks to using SOAs 

Although SOA was designed with the aim of helping businesses move away from their legacy systems, the speed of technological innovation means that there are now a number of drawbacks to using this older architecture. Let’s explore why SOA may no longer be the best option for businesses that want to complete a digital transformation.

Complex services

SOA has a higher level of complexity compared to other legacy architectures. Services exchange messages to carry out duties and just a single application can have a message volume of millions. This results in a need for careful management and orchestration.


Due to the loose coupling of services, managing service dependencies, ensuring compatibility, and enforcing policies can be challenging. Detailed governance mechanisms can make this easier.

Increased overheads

While the simplification of creating services can save businesses money, the initial cost to implement SOA can be large in terms of development and technology, as well as human resources.

Furthermore, the additional layers of communication and indirection in SOA can require high-bandwidth servers to avoid any impact on the system performance and response times.

Testing and Debugging

The distributed nature of services and their dependencies can make SOA testing and debugging much more complicated, as every service needs to be tested independently. While this can reduce the impact of testing on the whole system, it is also more time and labor-intensive. It can also be difficult to predict how changes in one service will affect all the others.

Should old systems be migrated or modernized?

Implementing SOAs can be used as part of a wider modernization strategy, which can include migrating legacy systems. When choosing whether to modernize or migrate existing systems, it’s important to understand exactly what would be involved and how it will support your business type and goals. 

Legacy system migration

While your legacy system may be outdated, resistant to modification, or too inflexible to meet your current business needs, it will still contain legacy information that often makes up the backbone of your organization. 

Migrating legacy systems to new infrastructure may be the only way to ensure future system growth. By integrating legacy data with new technologies, these systems can continue to provide value for your business. 

Legacy modernization

Legacy modernization involves modernizing certain aspects of your legacy system. It is an ongoing process that seeks to streamline workflows and improve business performance. 

Modernizing legacy systems can include automated migration to allow legacy coding to work on modern platforms. This can provide the flexibility and scalability necessary for businesses to remain competitive. 

OpenLegacy Hub

OpenLegacy supports modernization strategies with their microservices-based API approach, which enables cloud-native functionality for legacy systems. In contrast to the complexity of SOAs, OpenLegacy’s architecture is highly granular, with each microservice serving a single purpose and all communication conducted via APIs instead of messaging or ESB. 

The lightweight technology can be developed in multiple coding languages, and OpenLegacy provides no, low, and full code formats, providing ease and control at every level. Smaller, cross-functional teams can take ownership of individual microservices for easy and quick testing, debugging, and alterations, which allows microservices to be more flexible, adaptable, and scalable than SAOs. 

Legacy system migration statistics. 

Image source

Top tips for implementing a legacy migration strategy

If you’re considering using service-oriented architecture, you’re probably also considering a modernization strategy. Here’s an overview of what to consider if legacy system migration seems like a good modernization option for your business. 

One-shot or parallel migration?

  • One-shot migration: If you choose one-shot migration, the process will normally be undertaken by your vendor, who will have extensive experience and can migrate your entire legacy system in one go. 

You’ll often find one-shot migration happening in industries such as telecoms, where a system with a single set of protocols needs to be transformed into a new system with another set of protocols. 

This strategy usually costs less but can affect your short-term business operations. It also requires extensive planning and testing before being undertaken. 

  • Parallel migration: With a parallel migration process, the transition of components and functionalities from your old legacy system happens gradually. Because it has multiple phases, this form of migration requires ongoing and continuous communication and cooperation between all parties involved, which is why it can also be known as continuous migration.

If you opt for this strategy, you’ll use an architecture like SOA or OpenLegacy Hub to enable both the new system and your old legacy system to work in parallel during the process. This is useful for businesses with large legacy infrastructures or those that operate applications used by significant audiences. 

While it can be more expensive than one-shot migration and requires considerable effort, parallel migration is safer, with minimal risks of failure, results in less downtime, and can save you time and money in the long run. 

Creating a legacy migration plan

A comprehensive legacy migration plan will ensure that the process is as efficient and risk-free as possible. These ten steps will help you migrate systems successfully.

  1. Evaluate legacy systems and assess proof-of-concept

Before making any decisions, you should evaluate your current legacy system. You need an understanding of what your current system does, including its core functionalities and which tools help your business to operate. This will allow you to identify what can be ported to a new system and what needs to be replaced. 

Your evaluation should encompass everything from coding to applications, and you will also need to identify how well things will work post-migration. 

This is also a good time to assess your proof-of-concept and establish the expectations for your modernized system. A proper risk assessment is key to this step, as is evaluating the chances of successfully migrating your entire IT legacy system as it is. 

  1. Perform a SWOT assessment

The four components of a SWOT analysis.

Image source

A SWOT (strengths, weaknesses, opportunities, and threats) assessment is the next step in planning a migration. You can apply this to both your legacy system and the migration process to develop an awareness of what you’re going to face and highlight any areas where there may be particular challenges. 

By identifying both the strengths and weaknesses of your legacy system, as well as your migration plan, you’ll have a better idea of where to invest and deploy resources to ensure a successful outcome. 

  1. Select your system migration plan

Once you have a better idea of where you are now, where you want to be, and what challenges you might face, you’ll be ready to build a system migration plan. The first step is deciding on a one-shot or parallel migration strategy. You can develop a plan that works for your business based on this decision.

Your system migration plan should list all the personnel (both in-house and outsourced) and resources needed to perform the migration. You’ll also need to include a forecasted budget and your ideal timeline.

  1. Prioritize standard software deployment and create organizational support

As part of your earlier assessments, you should have identified and listed the core software that helps your business function. This could include existing software that will work with the new or modernized system as well as replacement software. Any software that provides core functions should be prioritized during the migration process. 

Knowing what should be deployed first is integral to ensuring a smooth and successful migration. Think of it like constructing a house: the key functions represent the foundation that the rest of your system will be built upon. 

  1. Set up a cloud-based infrastructure

With all your planning ideas listed, you now need a cloud-based infrastructure to migrate to. This infrastructure will encompass everything from hardware and software components to servers, storage, and tools for services and management. This initial infrastructure must meet all the needs that you identified earlier.

Of course, two of the major benefits of migrating legacy systems are flexibility and scalability, so as long as the infrastructure meets your initial requirements, you can worry about everything else later. 

  1. Implement robust security authentication and encryption techniques

Another benefit of migrating legacy systems is increased security, but this doesn’t mean you can become complacent. Your data may still be vulnerable while in your legacy system and can often be especially at risk during the migration process. 

This is particularly relevant for certain industries. You must ensure your data is protected at every stage, otherwise, you place it at risk. This means implementing robust authentication and encryption throughout the migration process. Making sure access is authorized and recorded can also help to reduce cybercrime vulnerability.

  1. Create a legacy system data backup

While it doesn’t happen often, things can go wrong with migration. To guard against this, you should include backups as part of your data management plan. It’s best to make a backup of all your data as close to the start of your migration as possible. 

With cloud modernization, it makes sense to have more than one backup, ideally to cloud storage. However, if you’re not already using this, a local backup can also be used. 

  1. Start your pilot migration and test KPI metrics

With potentially dozens of metrics that can be used to measure migration success,  you should concentrate on the ones that matter most to your business. During the pilot migration, these KPIs might include factors such as time, disruption, and costs.

As you move forward with your migration, you may also want to start measuring infrastructure and application performance, or the experience of end users.

  1. Manage your brand-new cloud infrastructure

Your new cloud infrastructure will include all the elements you need for successful cloud-based computing, such as:

  • Networks
  • Virtualization resources
  • Servers
  • Data storage 

You also need to think about some form of UI (user interface) to manage the different components in your infrastructure. You may decide to utilize IaaS (infrastructure as a service), or you may look at other tools. 

Ultimately, you want to be sure you have the processes and tools you need to effectively manage your infrastructure and ensure resources are allocated and delivered as required. 

  1. Monitor governance compliance

Depending on the amount of data you handle, as well as its sensitivity, you may or may not have a CCO (chief compliance officer). Either way, you’ll be subject to certain laws and regulations that cover how you collect, handle, and store data. During a legacy system migration, you need to ensure that data compliance ‘after’ matches or improves upon the levels from ‘before’. 

This means you need to monitor compliance with any relevant regulations during and after the migration process. Failure to meet compliance requirements can lead to financial penalties or worse. 

Unleash your business's true potential by migrating legacy systems with OpenLegacy

The advancement of technology is not going to slow down, so you need to make sure that your business can flourish and remain competitive in the digital era. Legacy systems can be highly restrictive, as they were designed and built at a time when there were fewer demands on them. 

By migrating legacy IT systems to cloud-based infrastructures, businesses can meet their full potential, but only if they choose the best modernization or migration method.

OpenLegacy uses a microservices-based API approach to modernize legacy systems without the need for extra layers of middleware. As a lightweight technology that can be developed using multiple programming languages, microservices provide loosely coupled, decentralized, and scalable access that can support your specific business needs and quickly adapt to whatever changes in technology the future may bring. 

Contact our sales team to learn more about how OpenLegacy can modernize your legacy system quickly and efficiently.


FAQs about migrating legacy systems

How is cloud migration helped by service-oriented architecture?

Service-oriented architecture was designed to address the architectural challenges that lead to the need for legacy system transformation. It offers improved deployments, security, and performance for businesses. Migrating applications and systems to cloud-native architecture provides even more benefits.

What is a legacy system vs a cloud system?

The primary difference between the two is that with a legacy system, you own and maintain the infrastructure, with your access limited to those networks. 

With a cloud system, the vendor owns or leases the servers, so any user can access the system through any browser. 

What is the difference between SOA and microservices?

With SOA, all modules and services are shared across your business and can be accessed by anyone with the authorization to do so. 

With microservices, the architecture is built using the independent functions of different services. 

Although they share some aims, understanding the differences between service-oriented architecture and microservices is essential for choosing the right option for your business.

We’d love to give you a demo.

Please leave us your details and we'll be in touch shortly