I understand (somewhat) what are differences between monolithic , microservices .
And also what is SOA it is a service consumer/provider architecture and microservice is subset of SOA. and they use Restfull/SOAP APIs to communicate.
So when a a request something he/she does using Rest/SOAP API but how in a Monolithic architecture a client request through which API? I searched all the links/blogs on google, videos on youtube but still I am not clear about this.
Or may be my whole understanding is not correct.
Sounds like you are a bit confused, I would really recommend you picking up a book on the subject.
Monolithic vs micoservice application is more about how you package and deploy your application and in some sense how coupled modules/subsystems are. The extreme example: you always deploy the entire monolithic applications for the smallest possible change, and in the microservice example you just need to make the same change to one service.
Rest API and SOAP are protocols for how (http) messages are passed between client <-> server and has nothing to do with monolithic vs micro.
Monolithic application can of course have public http API's, and it might not be possible for a user (sending request) of that API to tell the architecture style of that application. And why would she care about that?
I think this is a nice start: https://martinfowler.com/articles/microservices.html
Related
I have 2 years in the IT industry,i love to read a lot ,but when i go deep in some subjects i see a lot of contradiction in somes articles,forum or terms that are used interchangeable.
I understand the difference between Soap and Rest.
When we want to communicate between backends, we can use either of these 2 approaches, each with its advantages and disadvantages.
Situation :
If i have an application, which can be monolithic or not, where I have a backend and I will only have a front end that consumes it. Usually we create a Rest Api so that our front end can consume it. But we will never think about exposing our backend with Soap.(Lot of reasons)
Questions:
1 -Is it okay if I say that Rest , in addition to allowing us to exchange information between application and application (backend to backend ), is it also useful when exposing services for our front end? And SOAP is only useful for Server - Server communication?
2 -And finally, if I expose a backend only for a front end, it is ok to say that we expose a web service or conceptually we say that it is a backend for frontend ?
Question 1: No the First question is wrong Assumption. We can say that in SOAP, XML is the only means of communication, while in Rest, the accepted means is JSON, while there are other formats like XML, JSON, PDF, HTML etc. and Ofcourse, XML can be converted back from server into UI Language and XML Request deciphered at Server for a Response. So, its not Ok to say that SOAP is only for Server - Server Communication.
2. No, when you have typically exposed backend only for consumption by a Front end, you can typically say that it is a backend for numerous front end client requests. But IMO, Backend for a front end is a monolithic webapplication, both bundled in WAR. so in that sense, any UI Request can request response from the Back end web service. Hope i am able to clear your understanding about web services.
I see that in your question there are actually 4 embedded independent topics. And probably because they are always used in conjunction it is sometimes tough to understand.
I will give a short answer first:
REST and SOAP both can be used for Client-Server and Server-Server integrations. But the choice will be dependent on the questions like where you want server-side UI technology/client-side UI technology or is it a single page application/portal technology, etc.
If you expose a single-backend for a single-frontend it's technically a BFF although the term BFF is used only in the case where you have separate-backends for each type of frontend application. e.g. one for mobile, one for web, one for IoT devices, etc.
The long answer is to clarify the 4 principles. Let me give a try at this by separating the topics into the below four headings:
1. Backend(Business Layer) vs Backend for frontend(BFF)
In classical 3-tier architecture (UI-Business Layer-Database) world, the middle-layer that consists of the business and integration logic is mostly referred to as backend/business layer.
This layer can be separated from the UI/Frontend using multiple different options like APIs(REST/SOAP), RPC, Servlet Technology, etc. The limitation with this 3-tier architecture is that, it is still tightly coupled to the type of users and use-cases are limited to web/browser based. It is not a good choice when you want to reuse the business-layer for both web and mobile as the mobile applications are required to be light-weight by principle.
That's where we lean on to multi-tier architecture with Backend For Frontend(BFF) as a savior. It's just a methodology to segregate the business-layers based on consumers.
2. Monolith vs SOA vs Microservices(Optimized SOA)
In a monolith world all the code components mostly UI and Business Layer sits in a tightly coupled fashion. The simplest example would be a Java Servlet Pages(JSP) application with Java as Business Layer. These are typically server-side UI technologies.
In Service Oriented Architecture(SOA), the usecases revolve around leveraging reusable business layer functions aka services. Here one would have to deal with UI-Server, Inter-Service and Server-Server integration scenarios. It's heavily service dependent, meaning it's like a spider-web of dependent applications.
The Microservices is an extension of SOA, but the approach is to keep a resource in focus instead of services to reduce the spider-web dependencies. Hence, self-sufficient and standalone service-clusters are the base of micro-services architecture.
3. SOAP vs REST Webservices
SOAP stands for Simple Object Access Protocol, typically used by the business-layer to provide user-defined methods/services to manipulate an object. For example look at the names of the services for accessing a book collection
To get a book getABook()
Get the whole list of books listAllBooks()
Find a book by name searchABook(String name)
Update a book's details updateABookDetails()
On the other hand, REST is representational state transfer which transfers the state of a web-resource to the client using underlying existing HTTP methods. So the above services for accessing a book collection would look like
To get a book /book(HTTP GET)
Get the whole list of books /books(HTTP GET)
Find a book by name /book?name={search}(HTTP GET)
Update a book's details /book/{bookId}(HTTP PATCH/PUT)
4. How to make a correct choice of architecture?
Spot the diversity of the application user groups and usages: This will help to understand the platform(web/mobile/IoT/etc), nature of the application and session-management.
Determine the estimated/required throughput: This will help you to understand the scalability requirements.
How frequently and who will be maintaining the application: This will help to gauge the application and technology complexity, deployment cycles, deployment strategy, appetite for downtime, etc.
In conclusion, always follow the divine rule of KISS: Keep it simple, stupid.
1.)
A webapplication is for H2M communication a webservice is for M2M communication through the web. The interface of the service is more standardized, more structured, so machines can easily use it and parse the messages.
I don't think it matters where your service consumer is, it can run in a browser or it can run on the server. As long as it can communicate with the service on a relative safe channel it is ok.
You design a service usually to decouple it from multiple different consumers, so you don't have to deal with the consumer implementations. This makes sense usually when you have potentially unknown consumers programmed usually by 3rd party programmers you don't even know or want to know about. You version the service or at least the messages to stay compatible with old consumers.
If you have only a single consumer developed by you, then it might be too much extra effort to maintain a service with a quasi-standard interface. You can easily change the code of the consumer when you change the interface of the service, so thinking about interface design, standardization, backward compatibility, etc. does not make much sense. Though you can still use REST or SOAP ad hoc without much design. In this case having a RESTish CRUD API without hypermedia is a better choice I think.
2.)
I think both are good, I would say backend in your scenario.
I am learning about microservices and I don't understand what the real difference
between creating a REST API and creating microservices?
I’m working in Go, but my question applies over all languages.
The Microservices approach is about breaking your system ("pile of code") into many small services, each typically has its own:
Clear business-related responsibility
Running process
Database
Code version control (e.g. git) repository
API (the protocol how other services / clients will contact the Microservice)
UI
The services themselves are kept small so as your system grow, there are more services - rather than larger services.
Microservices can use REST, RPC, or any other method to communicate with one another, so REST or an API is really orthogonal to the topic of microservices...
Reference: What is an API? In English, please.
API = Application Programming Interface
Microservices = an architecture
In short
Microservice should expose a well-defined API.
Microservice is the way you may want to architect your solution
API is what your consumers see.
You can expose API without microservices in the backend (in fact, most non-training scenarios don't require microservices).
You may want to read http://samnewman.io/books/building_microservices/ before you decide on using microservices (unless this is for training purposes).
Microservice is well defined when you are following SOC - seperation of Concern on the entity/domain level ,where each entity / domain are independent of any other service.
for example user service will only be responsible for storing, updating and deleting user related informations.
Microservice backend and frontend microservice can further be splitted in 2 parts
frontend microservice which exposes rest endpoint just like Web API
backend microservice which actually perform all the operations.
Rest API is more of endpoints exposed to outer world and can be used with microservices as well, as explained above.
The majority of the answers is based on the old-school understanding of API as a programmatic interface. Nowadays, this meaning is melted and start confusing people becuase some developers started (for simplicit or by mistake) interpred the API of an application as the application per se. In such case, it is impossible to distinguish between the modern API and Microservices. Nonetheless, we can say that an API-application can comprise many Microservices, the most of which interact within the application via Microservice's APIs while others may expose their APIs as Applications's APIs. Also, a Microservice (as a service) may not include other Microservices (services), but may orchestrate a composition of Microservices via API-bases invocations. Applications may contain Microservices but, in the best practices, may not contain other Applications.
Microservices
A microservice architecture is about slicing an application logic into small pieces or "components" that can act between them and/or be exposed through an API.
API
A (web) application need to design the business logic with all set of object entities (model) and possible operations on them.
An (Application Programming Interface][https://en.wikipedia.org/wiki/Application_programming_interface) is a way of making the requests to an application by exposing specific entry-points that are in charge of invoking the appropriate application operations.
ReST(ful) APIs
("ReST" as in Representational State Transfer) are APIs complying with at least these 5 constraints:
User-interface is distinct from data storage and manipulation (Client-Server architecture)
No client context is stored on the server ("stateless")
Server responses must, implicitly or explicitly, define themselves as cacheable or not
Client does not have to be aware of the layers between him and the server
Response/request messages must be: be self-descriptive; allow to identify a resource; use representations allowing to manipulate the resources; announce available actions and resources ("Uniform interface").
"The real difference"
So, while these notions are obviously related, they are clearly distinct concepts:
Being ReSTful or not, an API exposes operations provided by a server that might (but not necessarily) be shelled into smaller components (microservices).
Also, while a typical web (ReST)API uses the HTTP protocol between the client and the server, components within a microservice architecture might communicate using other protocol(s) (e.g. WAMP, AMQP, JSON-RPC, XML-RPC, SOAP, ...)
In layman's term, if you have a web API server and you split them into several independent mini servers, use a proxy-server and load-balancer to clusterize them, and (optionally, give each a separate database entity), that is a microservice architecture.
I'm new to the concept of REST. And so far I've used a REST client (Advanced REST client) to make all the requests. But I don't understand the point of it all if I have to use a REST client to access the web service. I mean how then is a layman supposed to access a web service in his browser? And can browsers at all access access web services? If yes then why do I need a REST client?
The layman access a REST service all the time, when they access a web site (though many web sites violate REST principles to varying degrees). The REST architectural style was arrived at by examining why HTTP worked well, and was then used the conclusions to influence how HTTP 1.1 improved on 1.0.
They aren't expected to access a REST web-service, because a web-service is a service which uses the properties used by websites to provide machine-readable rather than human-readable data. A RESTful web-service tries to do this by taking advantages of how HTTP works and working with that. (The earliest "web services" seemingly started with the assumption that the web was a failure and needed to be coerced into working with the sort of RPC model that had been used previously, despite the fact that if this was true there'd be no advantage in using the web rather than the existing RPC protocols).
The layman therefore would more likely use an application that in turn used web services (whether that application was a web application, desktop, mobile, or whatever). The layman uses them the same way that they use any programming techniques; they use something devs built using them.
And can browsers at all access access web services?
Often they can get at least read-only access and sometimes a bit more. When this is the case it can be extremely useful for debugging.
I've been reading around trying to understand what RESTful API is all about. I guess I understood the general outlines and a bit about how it's related to HTTP and all that.
In fact, one of the jobs I recently applied for required a 'must' knowledge of a RESTful API!! The job description was messy anyway and seemed it had been written by an HR person, or somebody who didn't actually have an advanced technical knowledge.
I fail to see how, as a frontend developer / UI/UX designer, I could benefit from the vague RESTful API stuff? What's the connection?! Should really be bothered?
Thanks!
Simple and Precisely NO.
For only a front End Developer; it is not necessary, it is must (or SOAP bases API) for BackEnd Application Developer.
I am Android app Developer, made REST api for my app and my friend is just working on Web Page UI for that APP.!
Ajax calls are little to know for you.!
But one should know little bit about APIs, it never hurts :)
RESTful api, and web services in general, are a way to abstract back ends from front end developpers. It allows front-end developpers to do their interfaces without the need to code any server-side logic.
Web services contain all the business logic. As a front-end developper, you'd need to know how to interact with such services, but the whereabouts of the api call are not required of you to understand.
Finally, it's a way to define clear separation between what the application looks like and what the application does.
REST is a way to think applications. To make short, the client is stateless and you use HTTP methods for what they are designed to in order to interact with your server resources. You also leverage HTTP status codes, media types, content negotiation (Conneg).
If you want to know more about principles of RESTful services and Web API, you could have a look at this link: https://templth.wordpress.com/2014/12/15/designing-a-web-api/.
Hope it helps you,
Thierry
From client perspective the two main differences between REST and other e.g. SOAP webservices, that you have to use stateless communication (so you won't have a server side session, login, logout, etc...) and you have to use hyperlinks as request templates instead of building request from scratch. Because of these constraints your client breaks much harder by API changes.
In relation to this question, I have a follow up question that I am still confused over. I have been asked to compair REST vs Web Services. From what I have learnt about REST, it is not a web service, therefore how can you compair the two? What does the question mean when it says REST in this respect?
REST is an architectural pattern for web services emphasizing the usage of URIs as resources with a small set of operations that may be performed on them (usually PUT, POST, GET, and DELETE). I'm guessing you are being asked to compare REST to the ws* standard web services which utilize a lot of other technologies (including SOAP, though SOAP itself is not a web service, it is just a protocol that happens to be used in ws* web services).
REST can be used to provide web services just like databases can be used to store names and addresses. REST is far more general purpose than simply a way of providing a web API.
REST is useful for building distributed systems. However, many people use Web Services (note the capitals, this usually denotes SOAP, WS-*) for building distributed systems.
Wow, I just saw the homework tag. That is one seriously mean question. There are industry veterans who could not come close to answering this question.
A more accurate question would be: Compare REST using HTTP versus RPC using SOAP for building distributed systems.
They probably mean REST verse SOAP. They're all web services in concept.
The abbreviation REST stands for "REpresentational State Transfer".
REST APIs are used to call resources and allow the software to communicate based on standardized principles, properties, and constraints. REST APIs operate on a simple request/response system. You can send a request using these HTTP methods.
Hence REST is just an API (an interface that allows you to build on the data and functionality of another application) architectural style.
On the other hand, web service is a network-based resource that fulfills a specific task. Yes, there's overlap between the two: all web services are APIs, but not all APIs are web services.