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So how do you actually use an index in elastic search?

Well, there's three ways we can talk about.

One is the RESTful API.

Now if you're not familiar with the concept of rest queries, let me explain it at a very high level.

It's just like how you request a web page from a web server from your web browser on your desktop,

so when you're requesting a web page on your browser like Chrome or whatever you use,

what's happening is that your browser is sending a rest request to a web server somewhere,

and for every rest request it has a verb like get or put or post and some sort of body that specifies

what it is that you want to get back.

So for example, if you're looking for a web page, you would send the rest query for a get verb and then

that get would request a specific U.R.L. that you want to retrieve from that web server. Now elastic

search works exactly the same way, over the same HDP protocol that web servers work across,

so this makes it very easy to talk to a search from different systems.

So for example, if you were searching for something on a elastic search, you would issue a get request

through a REST API over http, and the body of that get request would contain the information about what

it is that you want to retrieve in Json format.

We'll see examples of this later on, but the beautiful thing about this is that if you have a language

or an API or tool or an environment that can handle http requests, just like talking to the Web normally,

then it can also handle elastic search.

You don't need anything beyond that, if you understand how to structure the Json requests for elastic

search than any language that can talk to http, can talk to an elastic search server.

Most of this course is going to focus on doing it that way just so you understand how things work

at a lower level, and what elastic search is capable of under the hood. But you don't always have to do

it the hard way.

If you're accessing elastic search from some application you're writing like a web server or web application,

often there will be a client API that provides a level of abstraction on top of those rest queries.

So instead of trying to figure out; how do I construct the right Jason format for the type of search

that I want, or inserting the kind of data that I want?

There's a lot of client API is out there that can make it easier for you.

They just have specialized API is for searching for things and putting things into the index without

getting into the nitty gritty of constructing the actual request itself.

So whether you're using Python or Ruby or perl or C++ or Java there is an API out there that you can

just use. Now in this course,

we're going to focus on using the RESTful API and not these higher level clients.

I don't want to single out one language as the only language that we used in this course.

If I were to go through this whole course using only the Java client it would be useless to people coding

in JavaScript or Python, for example, but all of the different clients in every language boil down to

rest calls in the end.

So if you understand the underlying http requests that these clients generate, you can understand any

of the client APIs, and you'll be able to move more easily from one language to another too.

So, please don't get upset that I'm not going to teach you how to write Java or any other specific language

to use elastic search.

The lower level information I'm giving you will make it easy to use the Java client API or the API for

any other language.

Finally, there are even higher level tools that can be used for analytics and one that we'll look at in

this course is called Kibana,

it's part of the larger elastic stack and that is a web based graphical UI that allows you to interact

with your indices and explore them without writing any code at all.

So it's really more of a visual analysis tool that you can unleash upon pretty much anyone in your organization.

So in order of low level the higher level API, there are restful queries so you can issue from whatever

language you want, you can use client API as to make things a little bit easier, or you can just use web

based UI to get the information you need as well. So those are the basic concepts of how elastic search

is structured and how you interface with it.

With that under our belt, we can talk more about how it works under the hood and how its architecture

works.