SOA Service Oriented Architecture
All services are self-contained and logical. They are like black boxes. In summary, we don't need to know the inner workings of a business service. To the outside world, it's just a black box that can interact using messages. For example, after the "Payment Gateway" business service gets the message "Check Credit" it will give the output: this customer's credit is available or not. For the "order system", the service of the "payment gateway" is a black box.
The following are the main features of SOA for Services:
A) SOA components are loosely coupled. When we say loosely coupled, it means that each service is self-contained with separate logic. For example, we took the service of a "payment gateway" and attached it to different systems.
B) SOA services are black boxes. In SOA, services hide inherent complexity. They only use interactive messages, and services accept and send messages. By virtualizing a service as a black box, the service becomes more loosely coupled.
C) SOA services should be custom: SOA services should be able to define themselves.
D) SOA services are maintained in a list: SOA services are maintained in a central repository. Applications can search for services in the central repository and invoke the appropriate services.
E) SOA services can be orchestrated and linked to achieve a specific function: SOA services can be used in a plug-and-play manner. For example, there are two services "Security Service" and "Order Processing Service" in "Business Process". Two types of business processes can be implemented from it: One, you can check the user first, then process the order, or vice versa. Yes, you guessed it, with SOA you can manage the workflow between services in a loosely coupled fashion.
Contracts, addresses and bindings
This is the standard term for the three SOAs. Every service must expose one or more endpoints in order for the service to be available for client calls.
- A contract is an agreement between two or more parties. It defines a protocol for how clients communicate with services. Technically, it has methods that describe parameters and return values.
- The address indicates where the service can be found. An address is a URL that points to the location of the service.
- Binding is what determines how this endpoint can be accessed. It determines how the communication is done. For example, you expose your service, which can be accessed using SOAP over HTTP or BINARY over TCP. Therefore, two bindings will be created for these communication mediums.
SOA for Web Services
Web services are the technical way to do it. Web services are the preferred standard for implementing SOA. In SOA, the services we need are loosely coupled. The SOAP protocol used by Web services to communicate is based on XML, which is very loosely coupled. It answers what is part of the service. SOA services should be able to describe themselves. WSDL describes how we can access the service. SOA services are located in a directory: UDDI description, from where we can get the web service. This is actually the implementation of the SOA registry.