Advaced Software Engineering

contributed by <handsomehsia J >

CH18 Service-oriented software engineering

18.1 SOA (Service-Oriented Architecture)

SOA is a style of software design where services are provided to the other components by application components, through a communication protocol over a network.

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There is 5 main HTTP methods:

GET：The GET method requests a representation of the specified resource. Requests using GET should only retrieve data.

POST：The POST method is used to submit an entity to the specified resource, often causing a change in state or side effects on the server.

PUT：The PUT method replaces all current representations of the target resource with the request payload.

DELETE：The DELETE method deletes the specified resource.

PATCH：The PATCH method is used to apply partial modifications to a resource.

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18.2 RESTful services

REST (Representational State Transfer) is truly a “web services” API. REST APIs are based on URIs (Uniform Resource Identifier) and the HTTP protocol, and use JSON for a data format) REST APIs can be simple to build and scale, but they can also be massive and complicated—it’s all in how they’re built, added on to, and what they’re designed to do.

Reasons you may want to build an API to be RESTful include resource limitations, fewer security requirements, browser client compatibility, discoverability, data health, and scalability—things that really apply to web services.

• REST is all about simplicity, thanks to HTTP protocols.
• REST APIs facilitate client-server communications and architectures. If it’s RESTful, it’s built on this client-server principle, with round trips between the two passing payloads of information.
• REST APIs use a single uniform interface. This simplifies how applications interact with the API by requiring they all interface in the same way, through the same portal. This has advantages and disadvantages; check with your developer to see if this will affect implementation changes down the road.
• REST is optimized for the web. Using JSON as its data format makes it compatible with browsers.
• REST is known for excellent performance and scalability. But, like any technology, it can get bogged down or bog down your app. That’s why languages like GraphQL have come along to address problems even REST can’t solve.

Comparing SOAP vs REST APIs

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18.3 Service engineering

18.3.1 Service candidate identification

identify possible services that might be implemented and define
the service requirements.

18.3.2 Service design

design the logical service interface and its implementation interfaces (SOAP and/or RESTful)

18.3.3 Service implementation and deployment

implement and test the service and make it available foruse.

18.4 Service composition

service construction by composition

step by step explaination

1. Formulate outline workflow
   use the requirements for the composite service as a basis for creating an ‘ideal’ service design.

2. Discover services
   search service registries or catalogs to discover what services exist, who provides these services and the details of the service provision.

3. Select possible services
   Your selection criteria will obviously include the functionality of the services offered. They may also include the cost of the services and the quality of service (responsiveness, availability, etc.) offered.

4. Refine workflow.
   This involves adding detail to the abstract description and perhaps adding or removing workflow activities.

5. Create workflow program
   During this stage, the abstract workflow design is transformed to an executable program and the service interface is defined.

6. Test completed service or application
   The process of testing the completed, composite service is more complex than component testing in situations where external services are used.

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參考資料：

1. https://medium.com/itsems-frontend/api-是什麼-restful-api-又是什麼-a001a85ab638
2. https://www.slideshare.net/software-engineering-book/ch18-service-oriented-software-engineering
3. https://dotblogs.com.tw/marcus116/2011/08/28/34524
4. https://www.upwork.com/resources/soap-vs-rest-a-look-at-two-different-api-styles
5. https://restfulapi.net/
6. https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods