API architecture - what to include - api

I am building a RESTful api for a project at the moment, the API will used for a web application, a mobile application and maybe eventually a desktop application.
There are a few instances where emails need to be sent to notify the user of an event that has happened within the application. What I am not sure of is where to does a an APIs job finish, should the API be responsible for sending the emails, or should the application send the emails based on what response comes from the API?
Basically what I am asking is where does an APIs job start and finish, is an APIs job just getting date from point A to point B? Or can it deeper capabilities?

It's a common mistake that many developers are still making. An API is just an interface through which you expose your underlying system to be accessed by other systems. How you expose your system depends on what functionalities you want to be visible to the external world. Moreover, your business logic should be entirely on your backend rather than spread over your mobile/web applications.
Having said that, my answer is yes! Don't think of it as "my API is sending emails". Think of it as "my MAIN SYSTEM is sending emails". Whether you want to expose this email functionality through your API or not is another completely different thing.

Related

What is the difference between System API and Process Api

Kindly, can anyone differentiate between System api and Process api?
Please provide answer in Generic terms, as i am unable to find on internet.
A system api abstracts from an existing system. It talks to the system in the language of the system (e.g. SOAP, direct Java calls, SAP calls, etc.). To the outside world it offers a clean API (usually REST with http and json). When you do a good job implementing your system api, you can exchange your existing system with a different/new one without changing the api of your system api to the outside world: Just implement a new system api with different adapter logic.
A process api should talk REST on "both ends". It calls one or several system apis to do its job. The process api orchestrates different jobs.
When you need more information, do a search with "api led connectivity"
A System API is a layer you build on top of a system, which handles all system specific connection quirks and settings. It then exposes these resources and it's logic in a standard format (usualy REST but you're free to choose something else like SOAP) to the rest of your API's. Like Roger Butenuth states:
"When you do a good job implementing your system api, you can exchange
your existing system with a different/new one without changing the api
of your system api to the outside world: Just implement a new system
api with different adapter logic."
A process API is where you keep your logic and orchestration, it does not 'talk' to end systems directly but instead connects to system API's to get it's data.
A process API should idealy only talk REST on both sides and can aggegrate data from multiple systems.
An example of a complex process API would be an "items you've ordered" API which takes in a user id as it's input, then talks to the system API of a CRM system to get the id used by the "order history system API".
However this API might only return a list of orders without any article information besides an article id. So our Process API then enriches this list with Article information fetched from "article information system API" with the id from the list.
I know it's out of the scope of the question, but for the sake of completeness i'l shortly explain the third variant as well:
An Experience API can be seen as a doorway into your API network, every (type of) client has different information needs and can communicate in different protocols.
It is the Experience API's responsibility to provide ALL the information required by a client in a format they support.
This takes the responsibility away from a client to know where the information needs to be fetched from.
(Customer info from CRM, Order info from proprietary sys one, Article info from article DB)
This concept of design has as a bonus that if when for example, the mobile app your company is making, gets some new functionality which requires extra data.
You can update the "mobille app experience api", which would leave your "superexpensive IBM Experience api" unchanged. Cutting down on development costs as you don't need to implement any changes in your other api consumers which would be the case had you had only one api.
I think the main difference is where you are implementing business process and rules/logics.
System API, within the scope of your design, are atomic APIs which will be used to construct higher level API (experience APIs). Process API is the orchestration layer where you can use Mulesoft flows to implement business process or logic.
System APIs do the heavy lifting work of CRUD operations.
Process APIs focus on business logic
System API's are underlying all IT designs are center frameworks of records that are regularly not promptly accessible because of its many-sided quality and network concerns. APIs give a method for concealing that many-sided quality from the client while uncovering information and giving downstream protection from any interface changes or legitimization of those frameworks.
Process APIs exemplify the fundamental business forms that cooperate with source and target frameworks or channels through an arrangement of framework APIs. For instance, in a buy arrange process, there is some rationale that is regular crosswise over items, geologies and retail channels that can and ought to be refined into a solitary administration that would then be able to be called.
And you will get some more clarity from this article https://dzone.com/articles/api-the-backbone-of-the-software-industry-know-how
System API and Process API will be part of API led connectivity.
System API is like awrapper service to either a main data base or saas platform
Process API involves application logic to validate search or query parameters

Clarify the meaning of APIs

An application-programming interface (API) is a set of programming instructions and standards for accessing a Web-based software application. Could someone explain to me in case of Google maps or Youtube which is the API and which is the software application? Are both visible to us and how? I know there are tons of articles out there, however I cannot clarify the above. APIs are like the waiters that transfer data among different machines. Okay, which exactly is the Google maps API and how do we call/use it? And which is the Google maps software application which is accessed by the API? When we write for example http://maps.google.co.uk/ do we call the API? My query may seem silly but I cannot find a good answer for that.
An application-programming interface (API) is a set of programming
instructions and standards for accessing a Web-based software
application.
Firstly, an API is not just for web-based software. Even your computer's OS provides APIs for hardware and software installed in the box.
For your question, an API is a method (code instructions) to connect your application to the features of another system. Allowing your application to use thay system's features as provided via the API.
Could someone explain to me in case of Google maps or Youtube which is
the API and which is the software application?
In the case of Youtube... Let's say you are making some Android video player app that you also want to be able to playback Youtube videos within that app. The software application is your own Android player code and to access the Youtube data you would use Youtube's Android API.
An example of using the API is this module : YouTubePlayer which as you can see provide API commands like loadVideo(String videoId, int timeMillis). Where videoId is the Youtube ID and timeMillis is the desired start time within the video).
When we write for example http://maps.google.co.uk/ how do we call the
API?
That's not how you would call the API. You must first visit the documentation of the API to see how it's expected to call features within your own app.
Google Maps : https://developers.google.com/maps/documentation/
Let's assume now you're coding a Javascript app, you can see the commands here as a startng point. There is also an example page showing code & result.
Simple terms:
API = the waiter
Application Software = the chef
You order from the waiter. The waiter brings it to the chef. The chef prepares the food. The waiter then brings you your food. Then you figure out what to do with the food; eat it, take it home, throw it on the floor, let your dog eat it, give it the homeless, etc...
A website, app, etc... would send an API request (your order with the waiter) to Google Maps (the chef). If your API request is valid, Google Maps will send back an response (your cooked food with the waiter). Then the website or app takes the returned data and displays it in their custom way to you.
In the case of Google Maps, apps like Yelp and others use Google Maps' API to request specific data; routes, addresses, etc… and then they display it on their app.
To make an API request/call you have access to use the API, format it correctly, and figure out what to do when Google sends a response back : https://developers.google.com/maps/documentation/
API is a set of functions and procedures that allow the creation of applications which access the features or data of an operating system, application, or other service.
An API is like building block for your application. Multiple API's can exchange data without knowing the other's implementation. In a good design pattern , we should design API's for different independent tasks and then merge them.
Google Maps API
This is the google maps API which a developer can use to develop his own piece of software.
Whenever we use any software and it's different features, we might be using their API's without generally knowing of them.
A software application is always visible to us, but an API is visible only if the developer wants to expose it for community use.
EDIT
Using Google maps API
This link has the documentation and examples on how to use the google maps API using javascript.
Hope it helps!
When you use software, web applications included, you are in most cases using a wrapped API. Software developers took the time to take a raw back end API which executes commands on the system, and made these endpoints easy to use for a specific user in an intended universe of discourse, or domain. End users do not have direct access to everything the API has to offer all at once, so it is not "available" in the same sense that it is available to the developers, but it is available in another sense because they are using the API to execute commands on the system by virtue of the Application that was Programmed with that Interface existing and working.
The Google Maps API is used to integrate the power of Google Maps into almost any application. It provides facilities for customization and much more. When you use the Google Maps webapp, it is, to my knowledge, built using many components of the Google Maps API, as are the Google Maps apps for any other platform, such as Android. Does this mean you as a user are using the API? Only through the application; the application talks to the API for you.
“An application programming interface (API) is a set of routines, protocols, and tools for building software applications. An API expresses a software component in terms of its operations, inputs, outputs, and underlying types. An API defines functionalities that are independent of their respective implementations, which allows definitions and implementations to vary without compromising each other. A good API makes it easier to develop a program by providing all the building blocks.
APIs often come in the form of a library that includes specifications for routines, data structures, object classes, and variables. In other cases, notably SOAP and REST services, an API is simply a specification of remote calls exposed to the API consumers.
An API specification can take many forms, including an International Standard, such as POSIX, vendor documentation, such as the Microsoft Windows API, or the libraries of a programming language, e.g., the Standard Template Library in C++ or the Java APIs.
An API differs from an application binary interface (ABI) in that an API is source code-based while an ABI is a binary interface. For instance POSIX is an API, while the Linux Standard Base provides an ABI”.
To speak plainly, an API is the messenger that runs and delivers your request to the provider you’re requesting it from, and then delivers the response back to you.
To give you a familiar example, think of an API as a waiter in a restaurant.
Imagine you’re sitting at the table with a menu of choices to order from, and the kitchen is the provider who will fulfill your order.
What’s missing is the critical link to communicate your order to the kitchen and deliver your food back to your table.
That’s where the waiter (or API) comes in. ”AHEM”
The waiter takes your order, delivers it to the kitchen, and then delivers the food (or response) back to you. (Hopefully without letting your order crash if designed correctly)
Now that we’ve whetted your appetite, let’s apply this to a real API example. In keeping with our theme, let’s book a flight to a culinary capital – Paris.
You’re probably familiar with the process of searching for airline flights online. Just like at a restaurant, you have a menu of options to choose from ( a dropdown menu in this case). You choose a departure city and date, a return city and date, cabin class, and other variables (like meal or seating, baggage or pet requests)
In order to book your flight, you interact with the airline’s website to access the airline’s database to see if any seats are available on those dates, and what the cost might be based on certain variables.
But, what if you are not using the airline’s website, which has direct access to the information? What if you are using online travel service that aggregates information from many different airlines? Just like a human interacts with the airline’s website to get that information, an application interacts with the airline’s API.
The API is the interface that, like your helpful waiter, runs and and delivers the data from that online travel service to the airline’s systems over the Internet.
It also then takes the airline’s response to your request and delivers right back to the online travel service .
And through each step of the process it facilitates that interaction between the travel service and the airline’s systems - from seat selection to payment and booking.
So now you can see that it’s APIs that make it possible for us all to use travel sites. They interface with with airlines’ APIs to gather information in order to present options back to us
The same goes for all interactions between applications, data and devices - they all have API’s that allow computers to operate them, and that's what ultimately creates connectivity.
API’s provide a standard way of accessing any application, data or device whether it is shopping from your phone, or accessing cloud applications at work.
So, whenever you think of an API, just think of it as your waiter running back and forth between applications, databases and devices to deliver data and create the connectivity that puts the world at our fingertips. And whenever you think of creating an API,
--MuleSoft

Should we call Web API from MVC application in same solution?

I am working on a project in MVC that has mobile application so one thing is clear that we have to use Web API so it can used in mobile application.
After creating API when we started to develop Web site we are confused and had discussion on whether to use API or directly access to the Business object. And we ended up after having opinion form more experienced developer to consume Web API instead of using Business object directly.
I'm having confusion regarding to this solution structure.
1) Why we should use Web API and make HTTP request (which is time consuming) to get or put data instead of business object directly which is in same solution.
2) After having arguments they said what if client wants to host API and web on different cloud server and apply scaling only on API or may be he want to have different url for accessing API and Web (which is some what logical). So in that case should we call Web API from MVC application in same solution?
3) If we're hosting API and Web on different hosting so it means our Web will use WebClient and have HTTP call on each navigation. Is it right?
4) If we'll business object form both API and Web hosting on different server then if something change in BL will need to update build on both server.
5) Or we should create only one project for API and can add views or html pages to develop Web interface so in that way we can directly call API from ajax.
As per my knowledge #5 is the best solution or API is only for 3rd party access. If we have DB, EF, data layer and business layer in same solution then we should not use API to make HTTP calls and directly access business object. (correct me if I'm wrong)API is needed when mobile application or desktop or any one want to access application so we can have same repository and data layer.
In my scenario I've to create API as we also have mobile application, and in project API side we called business layer (separate project) and business layer communicate to data access layer (separate project). So my question is if we host our API and web to different servers then calling API which is a HTTP request may take longer rather than using method from business layer as we create the project and we've .dll of business layer. In API controller we just convert out put of our business to json format.
I've searched on internet but didn't get convincing answer. I've found a blog http://odetocode.com/blogs/scott/archive/2013/07/01/on-the-coexistence-of-asp-net-mvc-and-webapi.aspx discussing same point but again in that blog my question is why we need to consider scenario #3?
I think you have answered your own question in writing, but really this boils down entirely to what your requirements are, and perhaps more importantly, what the strategy for your application is.
First of all, using Web Api over accessing Business Objects directly (by which I think you mean through viewmodels etc) only makes sense if you are controlling access of data client side.
If you only have a requirement for consuming data from client side within a particular application, then hosting Web API within the same project makes sense. Sometimes, for instance when building a SPA or rich-client web app, then using Web Api within the same projhect is sufficient, as they are only intended to be consumed by that application.
Where you see a requirement for different versions of the same application (mobile, tablet, web etc), then moving the Web Api to a separate project makes sense, as each application can then access the same API. This Web Api would contain your data access and business logic layers within it. This allows complete separation of your projects then, and provides maximum reusability, and ensures consistency in data between different versions of your project. Obviously with this set up, your Web Api layer is seperate and can be tested/deployed/scaled separately.
So in summary, you need to consider your requirements and assess the technologies available to you to achieve them. Using the above I hope you understand where Web Api fits in and what it can provide.

Common Session for Windows Store Application

Our Team is trying to build multiple Windows 8 Store Apps for an enterprise.
How do we maintain a common session for all apps(where we store data which need to be shared)?
How do we enable direct interaction between the apps developed i.e. sharing objects or string(JSON) among the apps?
There is not built in way to do this. Realistically you probably have three options to share data between applications.
The first is to use the cloud / web services. This makes the most sense as you'd have full control about what is shared, authentication etc. Using libraries such as SignalR could let you add real time functionality between the applications as well as multiple users.
The Share contract, by using custom data formats you could enable the apps to share specialised data between each of them. This can make sense if the user has a set of data they want to send to another application to enable a quick piece of workflow as the Share target is only partially launched. This also is limited in that it's enabled by user action.
Custom protocol handlers, by giving each app it's only protocol my-custom-app:///some-action?param1=value etc then you can pass data between apps, note this launches the app in question when you launch that uri. This would be best for more longer running scenarios.
I'd suggest a combination of all three depending on the user action. Cloud services to store the data for the user and then a mixture of Share and Protocol to enable to the user to smartly move the apps seamlessly.
Here exactly the same question as yours. In short: there is no such ability. Sometimes I think that it will be easier to share data via Internet that in device.

Prevent Application changes breaking API

I have an application which I am currently writing an API. This is the first time I have created an API from start to finish and have read lots of good articles and how to do this. However a lot of that material focuses on the API development specifically (as it should) but have not found anything that touches on how to ensure the API doesn’t get broken by changes which happen within the application project.
My application consists of a ASP.NET MVC web app which makes calls to a Service Layer to undertake CRUD like operations. So to get a list of all the users in my app the MVC app calls the service layer and asks for them and is presented with a collection of users. My API (WCF Web API) also uses this service layer internally and when I request a list of users, again I get back a collection of users (JSON, XML etc).
However if for some reason another developer changes the underlying User domain object by renaming a field say surname to last name then this potentially is going to break my API as the Service Layer is going to return to my API a user object with a new field name when its expecting something else. My API does in fact have its own representation of objects which get mapped to the application objects when requested but this mapping will not map the surname property and will be returned as null.
Therefore do all changes in the app have to be strictly controlled because I provide an API? If so then do you have to change your app and API in tandem? What if changes are missed? The aforementioned doesn’t seem correct to me hence my post to seek greater knowledge.
Again I’m quite new to this so any help on this would be much appreciated.
It is inevitable that your application will evolve, if you can create new versions of an API as you applications evolve and support the older versions, then give notice of when older APIs will become obselete.
If you are owning the API design and you don't really want anyone to pollute your design. Introduce dedicate DTOs for your API use. Which be mapped from the underpinning domain models. But your presentation (via xml or json) won't change even underlying models change frequently.