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In this video we will discuss Application
Programming Interfaces, or APIs. Specifically,

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we will discuss: What an API is, API Libraries,
REST APIs, including:

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Request and Response. An API lets two pieces
of software talk to each other. For example

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you have your program, you have some data,
you have other software components. You use

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the API to communicate with the other software
components.You don’t have to know how the

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API works, you just need to know its inputs
and outputs. Remember, the API only refers

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to the interface, or the part of the library
that you see. The “library” refers to

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the whole thing. Consider the pandas library.
Pandas is actually a set of software components,

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many of which are not even written in Python.
You have some data.

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You have a set of software components.
We use the pandas API to process the data

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by communicating with the other software components.
There can be a single software component at

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the back end, but there can be a separate
API for different languages. Consider TensorFlow,

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written in C++.
There are separate APIs in Python, JavaScript,

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C++
Java, and Go. The API is simply the interface.

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There are also multiple volunteer-developed
APIs for TensorFlow; for example Julia, MATLAB,

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R, Scala, and many more. REST APIs are another
popular type of API. They enable you to communicate

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using the internet, taking advantage of storage,
greater data

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access, artificial intelligence algorithms,
and many other resources. The RE stands for

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“Representational,” the S stands for “State,”
the T stand for “Transfer.” In rest APIs,

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your program is called the “client.” The
API communicates with a web service that you

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call through the internet. A set of rules
governs Communication, Input or Request, and

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Output or Response. Here are some common API-related
terms. You or your code can be thought of

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as a client. The web service is referred to
as a resource. The client finds the service

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through an endpoint. The client sends the
request to the resource and the response to

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the client. HTTP methods are a way of transmitting
data over the internet We tell the REST APIs

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what to do by sending a request. The request
is usually communicated through an HTTP message.

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The HTTP message usually contains a JSON file,
which contains instructions for the operation

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that we would like the service to perform.
This operation is transmitted to the web service

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over the internet. The service performs the
operation. Similarly, the web service returns

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a response through an HTTP message, where
the information is usually returned using

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a JSON file.
This information is transmitted back to the

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client.
The Watson Speech to Text API is an example

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of a REST API. This API converts speech to
text. In the API call, you send a copy of

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the audio file to the API; this process is
called a post request. The API then sends

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the text transcription of what the individual
is saying. The API is making a get request.

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The Watson Language-Translator API provides
another example. You send the text you would

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like to translate into the API, the API translates
the text and sends the translation back to

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you. In this case we translate English to
Spanish. In this video, we’ve discussed

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what an API is, API Libraries, REST APIs,
including Request and Response. Thank you

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for watching this video.