REST API concepts and examples

welcome today I want to talk about what an API is and why it's important in web development API stands for application programming interface and basically it's something that allows one piece of software to talk to another now there's lots of different kinds of api's but when you hear people talk about Twitter's API or Google's API what they're talking about is a REST API and a REST API stands for representational state transfer now it doesn't have to be the case but usually a REST API works pretty much the same way a website does you make a call from a client to a server and you get data back over the HTTP protocol now I think one of the best ways to show the many similarities between a REST API call and loading a normal web page can be found with Facebook's graph API for example let's pull up YouTube's face bowd facebook.com slash YouTube and we're all familiar with what a facebook page looks like it shows how many likes the YouTube page has things like that but now let's change the WW part to graph dot facebook.com slash YouTube and what we get back is a response to our API request we've made an API request in our browser to Facebook's graph API now what we get back might appear to be gibberish to the human eye but it's actually JavaScript object notation or JSON formatted data it's structured data organized according to key value pairs the same way an Excel spreadsheet is structured with key value pairs and you might ask for the data that's in cell a16 you can ask a JSON array for the data if you want to know how many likes this Facebook page had for the data contained under the key likes and all modern programming languages will be able to interpret this JSON response one more concept I want to introduce is the idea of parameters let's reload that same Facebook API request but this time let's add fields equal ID name and likes now when we refresh the page you see that only ID name and likes have been returned that's because these parameters have filtered the data that we get out of this response now let's take a look at another API example one that I think's really cool is provided by Google Maps and it allows you to take a city name or even an address and turn it into a set of GPS coordinates as comm / maps / api / geocodes last jason so if you remember what we just talked about the server that we're calling is maps out Google API is calm and then the particular resource we've drilled down it's the Maps resource and then the API resource and then the geo code resource and we've even added Jason as a resource and that's because the Google Maps API can return data in a number of different formats and then we'll add the following parameters will add address equals Chicago and sensor equals false and as you can see we got another JSON response and if we look in the JSON array and we go to the key results and then the key geometry and then the key location we see the latitude and longitude coordinates for the city of Chicago now that's great in oli we got the geo location coordinates for Chicago but what do we do with them well let's mash to api's together and take those geo coordinates over to instagram and plug them into instagrams media search in point so in order to access the Instagram media search in point without having to write any code we're gonna head over to Instagram comm slash developers and then on the left hand side click on API console and we'll be able to use this API console that's provided by API G or Apogee in order to make requests to the Instagram API without needing to write any code and you can see if you click on the drop down on the Left there's a whole bunch of API is that this thing is set up to allow you to play with but for now we're gonna use Instagram and we're gonna be using the Instagram media search in point which you can see is that API Instagram comm / version 1 v 1 / media / search and then we're gonna set the following parameters and you can see that they're added to our URL request up at the top of the screen we're gonna set lat equal to 41.87 and longitude equal to negative 87 0.62 and we'll set a distance of 20 meters we click send and we get back this information about a request we see it's a get request and it shows where it was sent and what parameters we passed in one of the parameters that we didn't say it was the access token because that was automatically set by the apogee interface and then below that in sort of the blue and purple you have key value pairs of header that we sent as part of our request and then if you look over at the response you can see we got an HTTP status code of 200 which means success that everything went okay and then there's some header information as well we've got ex rate limit limit which is 5,000 which is the total number of requests you can make to the Instagram API using one access token during one rate limit period and then down below you can see x-ray limit remaining which is a 40,000 994 which is how many requests we have remaining in this rate limit window and then there's some information about cookies and the content-type application JSON things like that and then if we scroll down we'll see the body of the response which is a JSON encoded array of all the images that matched the geo coordinates that we passed in and there's information such as you know what filter was used in order to take the integrand picture how many likes it receives how many comments information about the user who posted it how many followers they have things like that and then of course there's also the images themselves and if we copy that image link and we take it up into our you all browser and we paste it in then you can see there's a picture from that location in Chicago you can even see the Chicago skyline in the background pretty cool right there's literally thousands of api's out there that you can tap into and take their data and mash it up pass it to another API chances are whatever website you want to work with they have some kind of API that you can use in order to consume their data api's that are available check out programmable web comm up until now we've only been consuming data from api's but you can also write data to api's but before we go down that road we need to talk a little bit about the concept of HTTP request methods I've linked to documentation in the description below but the big two that you really need to know are get and post now a get request is what you use to consumed it and that's what you've seen us do so far by passing these URL parameters in order to get data back from the API but a post request for writing data to the API in the best practice is to actually put the data in the body of the request now normal web browser doesn't allow you to put data in the body of a request but what you can do is you can install this handy extension called postman restclient the nice thing about working with postman is you can make more complex API requests for example you can choose any one of the available HTTP requests method and you can see a list of them here second you can add a body to your HTTP request and finally you can add headers so let's use the postman client in order to send a tweet out over the Twitter API before we do that though let's talk briefly about the concept of authentication obviously you need to give some kind of event ocation if you're gonna be saying tweets out because otherwise you could send tweets from my Twitter account and I could send tweets from yours and what a lot of these big online websites are using for their authentication is what's known as oo auth or OAuth 2 let me just say briefly basically what you're doing is you're getting credentials kind of like a username and password although they're called a client ID and a client secret and then you're exchanging those for what's known as an access token and then you pass that access token to Twitter and Twitter knows that the request to make the tweet is coming from you so it sends out the tweet from your Twitter account okay so let's go ahead and send out a test tweet using the postman rest client we'll select post as our HTTP request method and then you'll see that the server rack sesang is at API Twitter comm and then as we drill down to our tweet sending resource we got our at version 1.1 of the Twitter API and then slash statuses slash update dot JSON and again that tells the Twitter API that we want JSON formatted data as a response and we've set the authorization header to our olaf 1.0 credentials and then down in the body of our post request we've set the key status to test tweet from postman and when we click send you'll see that there's information about what time the tweet was created the tweet ID that it was assigned information about my Twitter account of the Twitter account that the tweet was sent from and then if we click over on my timeline and we refresh the page you'll see sure enough that the test suite we sent out shows up [Music] 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Keywords: API, REST API, What is an API?, API Example, Twitter's API, Instagram's API

Id: 7YcW25PHnAA

Length: 8min 53sec (533 seconds)

Published: Mon Jul 14 2014