@SpringBootApplication

等价于

@Configuration
@EnableAutoConfiguration
@ComponentScan

gae cron timer

The App Engine Cron Service allows you to configure regularly scheduled tasks that operate at defined times or regular intervals. These tasks are commonly known as cron jobs. These cron jobs are automatically triggered by the App Engine Cron Service. For instance, you might use a cron job to send out an email report on a daily basis, or to update some cached data every 10 minutes, or refresh summary information once an hour.

The handler can be as simple as a Servlet in the app. The Servlet URL mapping in web.xml should be the same as the cron job URL.(无spring时，url映射是通过 web.xml 中的配置完成的)

exceeded the time deadline,（超过时限）

Cloud Datastore

Concept Cloud Datastore Relational database
Category of object Kind Table
One object Entity Row
Individual data for an object Property Field
Unique ID for an object Key Primary key

Unlike rows in a relational database table, Cloud Datastore entities of the same kind can have different properties, and different entities can have properties with the same name but different value types. These unique characteristics imply a different way of designing and managing data to take advantage of the ability to scale automatically. In particular, Cloud Datastore differs from a traditional relational database in the following important ways: