Microservices are an architectural style: one application is split into small, independently deployable services, each built around a business capability. A web service is an interface that lets software exchange data over a network using web standards such as HTTP, XML or JSON. Microservices often communicate through web services, but the two terms answer different questions.
Key Takeaways
- Microservices describe how an application is structured; a web service describes how software communicates over a network.
- The W3C defined a web service in its Web Services Architecture note of 11 February 2004 as a system for interoperable machine-to-machine interaction, described in WSDL and used through SOAP messages.
- Many modern web services are REST-style HTTP APIs that exchange JSON, so XML and SOAP are common but not required.
- The name “microservices” was settled by a group of software architects in May 2012 and popularized by James Lewis and Martin Fowler’s article of 25 March 2014.
- Microservices bring independent deployment and scaling, at the cost of network latency, harder testing and more operational complexity.
If you are not quite well versed in all the technological concepts that are nowadays appearing at a rather fast pace, nobody can blame you. There are just so many different things, programs, and aspects to consider that it is practically impossible for anyone to know just about everything on this topic.
Yet, some things are definitely worth learning, which means that you should get more info on certain technological aspects that are now available.
The fact that you are here tells me that you are ready to learn and that you are actually interested in two precise concepts. In other words, you are not here to learn about some random aspects that I might throw at you just because I feel like it.
Instead, you want to learn specifically about microservices and web services, as well as the difference between these two concepts.
Well, you have definitely picked a great topic. These two approaches can certainly get confused by people who are not actual tech wizards. If you have been confused with them too, don’t worry.
That is completely normal, and I am sure that even the experts and wizards have been there at some point. You have two options now if the confusion is overwhelming you.
Basically, you can either choose to forget about it all and stop being interested in technology in general, or you can decide to get the confusions cleared up and understand the difference between these two concepts once and for all.
I suppose you know which step I suggest you should take. Plus, given that you are still reading, I am quite sure that you are ready to take that step and finally get your facts straight.
Let’s start with web services: https://www.tutorialspoint.com/webservices/what_are_web_services.htm.
What Are Web Services?
If you really want to understand the difference between these two rather different notions, then you will first need to learn about them individually. In short, you will have to figure out what both of the concepts actually represent.
Then, the difference will become pretty clear and obvious all on its own. So, let us begin with the first notion.
A web service is a software system that lets applications exchange data over a network, usually over HTTP, using agreed standards and data formats such as XML or JSON. The software that asks for data is called the service requester, and the software that processes the request and returns the data is the service provider.
To be more precise, it allows different systems and platforms to understand each other even if those were written in different languages. Classic web services built on the W3C model make this possible with XML: SOAP carries the messages and WSDL describes the interface. Many modern web services are REST-style HTTP APIs that exchange JSON instead, so XML is common but not required.
What Are Microservices?
Now that you, hopefully, understand what web services are, it is time to take a closer look at microservices. Microservices are an architectural style in which one application is built as a suite of small services, each running in its own process and built around a specific business capability. The application will, thus, be a collection of separate services that can function properly together.
Each microservice can be developed, deployed and scaled by a small team independently of the teams working on other services in the same application. That independence can shorten release cycles, although testing the system as a whole becomes harder because the services talk to each other over the network.
Microservices can also improve fault isolation: a failure in one service does not have to take down the whole application, provided the other services are designed to cope with it, for example with timeouts and circuit breakers. In simple words, microservices are the alternative to a monolithic architecture, in which the whole application is built, deployed and scaled as one unit.
How Are These Different?
After both of these concepts have been explained in more detail to you, I suppose that you can guess on your own how they are different.
Yet, I believe it is important to make small and clear microservices vs web services comparisons, so that you can stop confusing these two notions once and for all. So, let me provide you with what you need.
Basically, a microservice is a small, independently deployable service that handles one business capability within a larger application, running in its own process and communicating with the other services over the network. It is like a small component of one app.
A web service, on the other hand, is a way of exposing an application’s functions or data to other applications over a network using web technologies such as HTTP. A web service is not a design for a whole application; it is an interface that any application, monolithic or microservice-based, can offer. As you can see, these two things are rather different, and I hope you have now learned how to tell them apart.
Microservices vs Web Services: Comparison Table
| Aspect | Microservices | Web services |
|---|---|---|
| What it is | An architectural style for structuring one application | A way for software systems to exchange data over a network |
| Scope | The whole application, split into many small services | A single interface or endpoint that other software calls |
| Typical standards | No single standard; often RESTful HTTP, messaging or GraphQL | SOAP and WSDL (W3C model) or REST-style HTTP APIs |
| Data formats | Any; JSON is common over HTTP | XML for SOAP; JSON or XML for REST APIs |
| Who consumes it | Mostly other services inside the same system | Internal or external applications, partners and mobile apps |
| Main trade-off | Independent deployment and scaling versus distributed-system complexity | Interoperability between platforms versus the overhead of network calls |
The two terms are not opposites. A monolithic application can publish a web service, and a microservice-based application usually exposes web APIs both between its own services and to outside clients.
How Do SOAP and REST Web Services Differ?
SOAP is an XML-based messaging protocol for web services. Each SOAP message is wrapped in an envelope with an optional header and a body, and it is most often sent over HTTP. SOAP version 1.2 became a W3C Recommendation on 24 June 2003, and the W3C XML Protocol Working Group that maintained it closed on 10 July 2009.
WSDL (Web Services Description Language) is the XML file that tells a client which operations a SOAP service offers, which parameters they expect and what data they return. WSDL 2.0 became a W3C Recommendation in June 2007, but many web-service toolkits still support only WSDL 1.1.
REST (Representational State Transfer) is an architectural style that Roy Fielding defined in his 2000 PhD dissertation at UC Irvine. REST is described by six constraints: client-server, stateless, cacheable, uniform interface, layered system and the optional code on demand. A REST-style web API identifies each resource by a URI and uses HTTP methods to read or change it, usually with JSON responses.
| Feature | SOAP web services | REST-style web APIs |
|---|---|---|
| Type | Messaging protocol | Architectural style |
| Message format | XML | Usually JSON; XML or HTML also possible |
| Interface description | WSDL file | No required format; often documented with Swagger |
| Transport | Most often HTTP; SMTP in some legacy systems | HTTP |
If you work with both kinds of service, the free XML to JSON converter and JSON to XML converter on this site help you compare the same payload in both formats.
Where Did the Term “Microservices” Come From?
According to James Lewis and Martin Fowler’s article “Microservices” (25 March 2014), the term was discussed at a workshop of software architects near Venice in May 2011, and the same group chose “microservices” as the name in May 2012. The article notes that Adrian Cockcroft at Netflix described the approach as “fine grained SOA”.
Lewis and Fowler define the style as building a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. The services are built around business capabilities, deployed independently by automated tooling, and may be written in different programming languages and use different databases.
Earlier, in 2005, Peter Rodgers, who had worked on research at Hewlett Packard Labs, described software components as “Micro-Web-Services” at the Web Services Edge conference, which shows how closely the two ideas have been linked from the start.
How Do Microservices Use Web Services?
Microservices use web services as their communication layer. Because each microservice runs in its own process, it needs a network interface so other services and client apps can call it. The common choices are:
- Synchronous calls over RESTful HTTP, where one service requests data from another and waits for the answer.
- Asynchronous messaging, where services publish and consume messages instead of waiting for each other.
- GraphQL, a query language some teams use to let clients request exactly the data they need.
In larger deployments, each service instance can be paired with a sidecar proxy in a service mesh. The containers are managed by an orchestration tool such as Kubernetes, and the proxies handle service discovery, load balancing, authentication and secure communication. For one practical question that arises at this stage, see which Kubernetes multi-tenancy approach to use.
For a wider look at why HTTP interfaces matter so much here, read why APIs are the building blocks of modern application development.
Are Microservices the Same as SOA?
Microservices are related to service-oriented architecture (SOA) but are not the same. SOA also splits functions into separate services that communicate over a network, and it is often used for system integration through standardized service contracts.
Lewis and Fowler describe microservices as preferring “smart endpoints and dumb pipes”: each service owns its own domain logic, and services are connected with simple RESTish protocols rather than complex protocols such as WS-Choreography. The same article notes that Netflix once called its microservice style “fine-grained SOA”, which reflects how closely the two are related.
Pros and Cons of Microservices
| Benefits | Drawbacks |
|---|---|
| Modularity: each service is smaller and easier to understand | Network calls between services add latency compared with in-process calls |
| Independent scaling: only the service under load needs more resources | Testing and deployment of the whole system are more complicated |
| Small teams can develop and deploy their services in parallel | Moving responsibilities between services is harder |
| Legacy monoliths can be modernized step by step | Data consistency across services needs extra patterns, because two-phase commits are seen as an anti-pattern |
The scaling benefit is the one most often cited. In a monolith that supports three functions, the whole application has to be scaled even if only one function is short of resources; with microservices, only that one service needs to be scaled out.
When Should You Choose Microservices?
Microservices pay off when an application is large enough that independent deployment and scaling outweigh the extra operational work. Use these questions as a checklist:
- Do different parts of the system have very different load? Independent scaling is a strong reason to split them.
- Do several teams need to release on their own schedules? Separate services let each team deploy without coordinating every release.
- Can you run continuous delivery and monitoring for many services? Microservices need automated deployment, log and metrics aggregation and distributed tracing to stay observable.
- Can you keep service interfaces stable? Sam Newman, author of Building Microservices (2015), recommends backward-compatible interface changes and consumer-driven contract tests instead of relying only on end-to-end tests.
- Would internal modules be enough? If the main goal is cleaner code, internal modularization of a single application may be simpler than many small services.
Whichever architecture you pick, you will still publish web services for clients and partners. Choosing a suitable back-end stack is covered in the best back-end frameworks for web development, and the benefits of the style are expanded in the advantages of microservice-based software architecture.
Frequently Asked Questions
Is a microservice a web service?
A microservice is not automatically a web service, but most microservices expose one. A microservice is a unit of an application’s architecture, while a web service is the network interface through which it can be called, often a REST-style HTTP API.
Is a REST API a web service?
Yes. A REST API that works over HTTP is a type of web service. The W3C’s 2004 Web Services Architecture work already distinguished REST-compliant web services from web services that expose an arbitrary set of operations.
What is the main difference between microservices and web services?
The main difference is scope. Microservices describe how a whole application is divided into small, independently deployable services, while a web service describes how one piece of software makes its functions available to another over a network.
Do microservices have to use HTTP?
No. Microservices often use RESTful HTTP, but they can also communicate through asynchronous messaging or GraphQL. The choice of protocol is one of the main technology decisions in a microservice architecture.
Is SOAP obsolete?
SOAP has not been withdrawn: version 1.2 has been a W3C Recommendation since 24 June 2003. However, the W3C working group that maintained it closed in 2009, and web APIs have increasingly moved toward simpler REST-based communication that does not require SOAP or WSDL.
