1. What is 'Google App Engine'?

peruvianwageslaveInternet and Web Development

Feb 5, 2013 (4 years and 8 months ago)

118 views


2008.10.07
Yoo

Hyunjeong


Google web application platform


Easy to build, easy to maintain, and easy to scale as
user’s traffic and data storage needs grow


No servers to maintain, with App Engine : just
upload an application, and it’s ready to serve your
users.



Providing a platform including database


호스팅을

GAE
에서

담당하여

개발자로

하여금


비스

개발에

집중할



있도록

제공


GAE
에서

제공하는

기능



Python


제공하는

기본

기능



BigTable
/GFS
기술이

뒷받침하는

견고한

Datastore



확장성을

제공하는

호스팅

공간



Google

account


SDK


이용한

로컬

개발



테스트




App Engine


통해



서비스

개발자들은






“Web Development that doesn’t hurt”(Ruby
on
Rails’s

모토
)
고통

없이

개발할



있는

선택권


갖게

된다
.
다만
,


선택에는

세가지의

제약이

따른다
.


1.
모든

코드는

반드시

Python
으로

작성해야

한다
.


2.
사용량

제한을

통해

비용

지불의

가능성이

존재한다
.


3.

모든

데이타는

구글

플랫폼에서

움직이며

구글이

갖게

된다는

점이다
.
이는
,
구글

플랫폼에

종속된

어플리케이
션은

쉽게

구글

플랫폼을

벗어나지

못하게



것이다
.



Google App Engine makes it easy to build an
application that runs reliably, even under heavy
load and with large amounts of data. The
environment includes the following features:


dynamic web serving, with full support for common web
technologies


persistent storage with queries, sorting and transactions


automatic scaling and load balancing


APIs for authenticating users and sending email using
Google Accounts


a fully featured local development environment that
simulates Google App Engine on your computer



Application run in a secure environment that
provides limited access to the underlying
operating system.



These limitations allow App Engine to
distribute web requests for the application
across multiple servers, and start and stop
servers to meet traffic demands.



The
sendbox

isolates your application.


Examples of the limitations of the secure
sandbox environment include:



An application can only access other computers on the
Internet through the provided URL fetch and email
services and APIs. Other computers can only connect to
the application by making HTTP(s) requests on the
standard ports.


An application cannot write to the file system. An app
can read files, but only files uploaded with the
application code. The app must use the App Engine
datastore

for all data that persists between requests.


Application code only runs in response to a web request,
and must return response data within a few seconds. A
request handler cannot spawn a sub
-
process or execute
code after the response has been sent.



App Engine provides a runtime environment
that uses the Python programming language.


Python version 2.5.2.



App Engine also provides a simple Python
web application framework called
webapp

to
make it easy to start building applications.


App Engine also includes the
Django

web
application framework, version 0.96.1


Providing a powerful distributed data storage
service



The App Engine
datastore

is not like a
traditional relational database. Data objects,
or "entities," have a kind and a set of
properties. Queries can retrieve entities of a
given kind filtered and sorted by the values of
the properties.


The following APIs are provided to access the
se services:



URL Fetch


Applications can access resources on the Internet usin
g App Engine's URL fetch service. The URL fetch service
retrieves web resources using the same high
-
speed Go
ogle infrastructure that retrieves web pages for many o
ther Google products.



Mail


The following APIs are provided to access the
se services:



Memcache


providing your application with a high performance in
-
memory key
-
value cache that is accessible by multiple
instances of your application.


useful for data that does not need the persistence and
transactional features of the
datastore
, such as tempor
ary data.



Image Manipulation



Developing and uploading applications for
Google App Engine using the App Engine
software development kit (SDK).


The SDK includes a web server application that
simulates the App Engine environment, including
a local version of the
datastore
, Google Accounts,
and the ability to fetch URLs and send email
directly from your computer using the App
Engine APIs.


The SDK runs on any computer with Python 2.5,
and versions are available for Windows, Mac OS X
and Linux.


Creating a simple request handler


Helloworld.py




Creating the Configuration File


App.yaml


Testing the Application


Start web server


Dev_appserver.py


Appcfg.py



Dev_appserver.py
hyunjeong
/



The CGI standard is simple, but it would be
cumbersome to write all of the code that uses
it by hand.


Web application frameworks handle these
details for you, so you can focus your
development efforts on your application's
features.



App Engine includes a simple web application
framework of its own, called
webapp
.


A
webapp

application has three parts:


one or more
RequestHandler

classes


a
WSGIApplication

instance


a main routine



Edit Helloworld.py



Testing


Edit Helloworld.py