---
title: "Applications"
date: 2019-03-13T18:28:09-07:00
draft: false
weight: 4
---
Building a brand new application is more work but is ideal for creating a custom solution.
**Note** It is now more recommended to integrate external services (e.g. integrate a new SQL Datatase with the Editor, add a new visualization...) to the core Hue APIs instead of building brand new application. This page gives good content in both cases. Feel free to contact the community for advice.
## Introduction and Overview
Hue leverages the browser to provide users with an environment for exploring
and analyzing data.
Build on top of the Hue SDK to enable your application to interact efficiently with
Hadoop and the other Hue services.
By building on top of Hue SDK, you get, out of the box:
+ Configuration Management
+ Hadoop interoperability
+ Supervision of subprocesses
+ A collaborative UI
+ Basic user administration and authorization
This document will orient you with the general structure of Hue
and will walk you through adding a new application using the SDK.
## Fast-Guide to Creating a New Hue Application
Now that we have a high-level overview of what's going on,
let's go ahead and create a new installation.
### Download, Unpack, Build Distro
The Hue SDK is available from [Github](http://github.com/cloudera/hue). Releases
can be found on the [download page](http://gethue.com/category/release/).
Releases are missing a few dependencies that could not be included because of
licencing issues. So if you prefer to have an environment ready from scratch,
it is preferable to checkout a particular release tag instead.
cd hue
## Build
make apps
## Run
build/env/bin/hue runserver
## Alternative run
build/env/bin/hue supervisor
## Visit http://localhost:8000/ with your web browser.
### Run "create_desktop_app" to Set up a New Source Tree
./build/env/bin/hue create_desktop_app calculator
find calculator -type f
calculator/setup.py # distutils setup file
calculator/src/calculator/__init__.py # main src module
calculator/src/calculator/forms.py
calculator/src/calculator/models.py
calculator/src/calculator/settings.py # app metadata setting
calculator/src/calculator/urls.py # url mapping
calculator/src/calculator/views.py # app business logic
calculator/src/calculator/templates/index.mako
calculator/src/calculator/templates/shared_components.mako
# Static resources
calculator/src/static/calculator/art/calculator.png # logo
calculator/src/static/calculator/css/calculator.css
calculator/src/static/calculator/js/calculator.js
Some apps are blacklisted on certain versions of CDH (such as the 'Spark' app) due to
certain incompatibilities, which prevent them loading from in Hue.
Check the hue.ini 'app_blacklist' parameter for details.
### Install SDK Application
As you'll discover if you look at calculator's setup.py,
Hue uses a distutils entrypoint to
register applications. By installing the calculator
package into Hue's python virtual environment,
you'll install a new app. The "app_reg.py" tool manages
the applications that are installed. Note that in the following example, the value after the
"--install" option is the path to the root directory of the application you want to install. In this
example, it is a relative path to "/Users/philip/src/hue/calculator".
./build/env/bin/python tools/app_reg/app_reg.py --install calculator --relative-paths
=== Installing app at calculator
Updating registry with calculator (version 0.1)
--- Making egg-info for calculator
If you'd like to customize the build process, you can modify (or even complete
rewrite) your own `Makefile`, as long as it supports the set of required
targets. Please see `Makefile.sdk` for the required targets and their
semantics.
Congrats, you've added a new app!
What was that all about?
virtualenv
is a way to isolate python environments in your system, and isolate
incompatible versions of dependencies. Hue uses the system python, and
that's about all. It installs its own versions of dependencies.
Entry Points
are a way for packages to optionally hook up with other packages.
You can now browse the new application.
# If you haven't killed the old process, do so now.
build/env/bin/hue runserver
And then visit http://localhost:8000/ to check it out!
You should see the app in the left menu.
### Customizing Views and Templates
Now that your app has been installed, you'll want to customize it.
As you may have guessed, we're going to build a small calculator
application. Edit `calculator/src/calculator/templates/index.mako`
to include a simple form and a Knockout viewmodel:
<%!from desktop.views import commonheader, commonfooter %>
<%namespace name="shared" file="shared_components.mako" />
%if not is_embeddable:
${commonheader("Calculator", "calculator", user, "100px") | n,unicode}
%endif
## Main body
%if not is_embeddable:
${commonfooter(messages) | n,unicode}
%endif
The template language here is Mako,
which is flexible and powerful. If you use the "`.html`" extension, Hue
will render your page using
Django templates
instead.
Note that we use Knockout.js to do the heavy lifting of this app.
Let's edit `calculator/src/calculator/views.py` to simply render the page:
#!/usr/bin/env python
from desktop.lib.django_util import render
def index(request):
return render('index.mako', request, {
'is_embeddable': request.GET.get('is_embeddable', False),
})
You can now go and try the calculator.