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Meet Spark
10:49Spark is a Micro-Framework that’s sole purpose is to get you up and running and rapidly developing web applications. After we discuss the project for the course, let’s go get it installed. It’s a breeze!
I'm super excited to
introduce you to the web
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application framework that we're gonna be
using for the rest of this course, Spark.
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Now Spark is unfortunately in a bit of
name space collision in the Java world.
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The Spark framework is not to be confused
with the database called Apache Spark.
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It's unfortunate that they
share the same name and
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it makes searching around
a little confusing at times.
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So, keep this in mind as you
start navigating these parts.
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The idea behind a microframework is
to keep things small, simple, and
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clear and Spark does just that.
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It is built for productivity and
design to get you up and running and
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ready for
rapid application development in no time.
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Part of the complaint of
Web frameworks in general,
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is that the more sophisticated they get,
the more they bloat and swell.
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There's usually tons of configuration, and
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you have to learn a whole new environment
before you can even write a simple page.
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Well microframeworks are not like that.
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In the Ruby programming world,
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a super tiny and
easy to use framework was created.
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It's called Sinatra.
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Now Spark and many other microframeworks
got its inspiration from Sinatra so
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you might hear it being
called Sinatra based.
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So get ready to start spreading
the news because this is awesome.
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Okay, so
before we get this framework installed,
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let's talk a bit about the project for
this course.
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So the actual idea for
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the creation of this course came
from one of your fellow classmates.
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As you probably know, we always ask you
for feedback and ideas for future courses.
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I usually get a direct message on Twitter,
something over email, and
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we put these suggestions out for
you to vote on.
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So one of your classmates shot me an email
saying, I'd love to learn Spark so
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I can get a site up and running quickly.
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And I thought that
sounded like a good idea.
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And I turned that into a request, and
into something you could vote on.
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So, check the teacher's notes for
more on the current voting system.
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And you all voted it up and
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we agreed that it made great sense to
have in our library, so here it is.
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Well that got me thinking, why don't
we remove me, as the middle man and
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just have a place where you
students can submit ideas yourself.
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Why don't we just build an app?
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And I thought,
that's a pretty simple web app.
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And then I was like, why not just
use one of those microframeworks.
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And then I was like, I'm writing a course
on Spark and I need a project and then.
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I was like, wow sparkception.
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So the project for this course, let's make
a site that takes ideas from students and
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then allows voting.
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Sound good?
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Let's go get Spark installed.
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Alright, so
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let's create a new project in IntelliJ
IDEA and we'll make a great old project.
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So do create new project and we'll
choose Gradle over here on the left, and
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if Gradle's new to you, check the
teacher's notes for a quick intro to it.
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Now we're going to use it because we're
going to use Spark as a dependency.
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So if we were going to publish this, we'd
want something like this for the Groupid.
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We'd want com Team Treehouse the reverse,
and we'll just call this Courses.
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And for the artifact ID we want
something like Course Ideas.
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Remember, this is what
the published jar would be named.
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Let's go ahead and choose Next.
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And let's choose create directories for
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the empty content roots automatically
that way it gonna be there.
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Awesome.
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Okay.
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So now the file, directories all there,
let's open up the source.
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Main, Java and let's add a new class here.
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New java class, and the class name is,
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let's do com.team
treehouse.courses and for
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simplicity's sake let's just call it Main.
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Okay.
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And in this file we'll make
our standard main call.
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I want you to see how
simple Spark actually is
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to get the prototype up and running.
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So we'll do the public static void main
and press tab, it builds it out for us.
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Okay, so now we're ready.
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So first let's add our dependency.
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So the site's called sparkjava.com,
I have it open over here.
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So sparkjava.com, and
up here there's this Download tab.
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So over here it tells us how to get it.
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So the group ID is com.sparkjava,
and then it's spark-core and 2.3.
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So let's go to build.gradle and
in the dependencies section here,
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we'll say compile.
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And we'll use the shorthand, we'll say,
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com.sparkjava, and
then spark-core, and then 2.3.
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Let's go ahead and click apply
the suggestion there that way when we ship
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this project, if we ever do,
Gradle will be shipped with it.
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Okay, so let's flip over to
the Gradle tool window, and
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in here we'll press this
refresh all Gradle projects.
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And bam, just like that, we have Spark and
all of its dependencies.
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So here's Spark and here's Jetty.
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And Jetty is the embedded
web server that's used.
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So, what do you say we flip
back to the documentation and
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take a quick look at the demo
under the documentation?
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So let's switch back.
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Let's go over here to documentation.
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And it says right here
this is what we wanna do.
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Let's just grab this line because
basically we have that same thing in our
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file, right.
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So I'm just gonna grab this and
I'm gonna flip back over and
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in our main Java we'll add that line.
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And let's see what happens.
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Let's close this Gradle project,
get it out of the way.
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Okay.
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So what does it say here?
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It says, we need to do
the static import of Spark.get.
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See it saw that.
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So again it's statically importing,
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there is a get method here and
it's off of the spark class.
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Cool, if it doesn't like your
lambda syntax, by default,
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some of the IDEs are set to 6 by default.
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But go ahead and set it to 8.
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Spark really shines when we're
using the lambda syntax.
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And if lambda syntax is new to you,
check the teacher's notes.
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But basically what it's saying here is
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called the static method get
with the path name /hello.
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Anything that's matching /hello,
and then it takes a lambda.
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In the lambda here,
there's two parameters that are taken.
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It's the req which is request and
res which is response.
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And then it returns,
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remember the [INAUDIBLE] the first
thing here returns hello world.
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So, this is a function that
will return hello world and
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it's passed a request and a response.
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This is,
what this lambda here is know as a route.
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It's actually a functional interface for
the route object.
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So what this means is that when an http
get request is made to our web server
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that is looking for the uri or the uniform
resource identifier of slash hello.
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Our function will be called and
hello world will be returned.
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Now we'll touch a bit more
on these requests and
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response variables in upcoming videos,
but for now let's just return that text.
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Could that really be all it took
to get things up and running?
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Well, let's give it a go, what do you say?
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So, let's choose run and we'll choose Run
for the menu here, we will choose Main.
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Okay, so
it says that Spark has ignited and
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it says that it's listening
on port 0.0.0:4567,
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so 0.0.0 is a code name for
all IP addresses on your current machine.
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So you can access that URL in
the URL bar of your browser,
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or you could just use another nickname,
which is localhost.
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So let's do that.
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So let's switch over to a new window here,
and we'll say localhost.
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Well, actually, first let's say that
we're gonna talk HTTP to localhost
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and I'm going to do a colon and
that's for the port which was port 4567.
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Now by default it listens on a different
port but we're specifically saying this.
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By default,
you don't need to specify the port.
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The port is 80 but we're specifying here
4567 and that's how you specify the port.
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Okay.
So then, let's look for /hello.
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Sound good, right?
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Whoa, look at that.
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A website.
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So, wait a second.
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All I need to do if I want another
page is just add a new route, right?
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So I know that we want a page when
someone just comes to our site.
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So that path is just /, right?
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So let's do that.
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Let's add Over here we'll just come in and
say get.
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If anybody comes to
just slash then we add,
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again, we'll add a request and a response.
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And let's make it say welcome students.
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Cool, awesome.
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And I save it, and if I come back over
here and I just do the slash, that should.
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What?
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You know what?
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I forgot to restart the server.
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The server is running.
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So there's this button here.
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This restarts.
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This will stop and re-run main.
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So notice that main is still running.
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So let's stop it and re-run it and
now let's go see if the slash is there.
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Welcome students.
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There it is.
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Woah.
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Bam.
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You just built a web application.
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It's for
sure gonna get more challenging, but
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you just tackled that in like
five minutes or something.
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That's pretty amazing right?
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Micro-frameworks for the win.
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Also, did you see how
clear that syntax was?
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Doesn't get much more clearer than that,
does it?
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But forgetting to restart the server is
going to bite you, I promise it will.
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You'll make a change and you won't see
it and you change it some more and
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you'll still not see it and
then do a facepalm like this.
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And you'll realize that it's because
you forgot to reset the server.
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It's actually a good thing to remember
that the server's constantly running,
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just waiting for any number of
requests to come in from wherever.
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Even though our request response loop for
that one request was finished,
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the server's still just sitting there
waiting to respond to the next request.
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Well, let's see if we can make
this app a little more dynamic.
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Why don't we make a site
that's more personal.
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Welcome, students isn't exactly
as personable as we can make it.
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Why don't we prompt for the user's name?
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Actually I think we have a little work on
making things look a little bit prettier.
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