Use simpleds to solve the persistent layer of Google appengine

Use

Simpleds

Solution

Google appengine

Persistent layer

Posted
By: chszs

Posted
On:

May 05 2010

 

Simpleds

Is

Gae

(

Google App Engine

) Provides an extremely concise persistence framework. It is only used for data storage.

API

Encapsulates a layer, providing the entity and

Java

Ing between classes.

Gae

Provides a very powerful service function that can persist data on the cloud, but it provides

API

To process persistence is very troublesome:

· Data Storage

API

The structure of the ing style is exposed to the underlying layer;

·

JDO

And

JPA

Of

API

It is too complex to complete simple tasks, and a large number of additional checks are added for relational databases, which affects performance.

Simpleds

The latest version is

1.0 RC1

, Which provides the following functions:

· Supports Level 1 cache and level 2 cache;

· Background tasks broke through

Gae

Of

30

Second limit;

· Optimized functions:

N + 1

The secondary query is converted into two queries and combined with the cache to improve the performance;

· Available

Simpleds

Comment or

JPA

Annotation for driver configuration;

· Supports embedded classes;

· Supported'

=

','

<

','

<=

','

>

','

> =

','

In

','

! =

','

Like

'And other operators;

· Supports paging query and cursors;

· Supports transaction processing.

Example of entity processing:

// JPA Retrieve by key <br/> model M1 = entitymanager. find (model. class, key); <br/> model m2 = entitymanager. find (model. class, key2); <br/> // simpleds Retrieve by key <br/> model M1 = entitymanager. get (key); <br/> List <model> L = entitymanager. get (key1, key2); <br/> // JPA persist changes <br/> entitymanager. merge (M1); <br/> entitymanager. persist (m2); <br/> // simpleds persist changes <br/> entitymanager. put (M1); <br/> entitymanager. put (l); <br/> model m3 = new model (); <br/> entitymanager. put (parentkey, M3); <br/> // JPA remove <br/> model M1 = entitymanager. find (model. class, key); <br/> entitymanager. remove (M1); <br/> // simpleds remove <br/> entitymanager. remove (key1, key2, key3); <br/>

Query example:

// JPA <br/> query = entitymanager. createquery (<br/> "select m from model m where M. createdat <=? 1 and M. createdby =? "<Br/>); <br/> query. setparameter (1, new date (); <br/> query. setparameter (2, userkey); <br/> return query. getresultlist (); <br/> // simpleds <br/> simplequery query = new simplequery (model. class) <br/>. lessthanorequal ("createdat", new date () <br/>. equal ("createdby", userkey); <br/> return entitymanager. find (query); <br/> // retrieve just keys <br/> entitymanager. find (query. keysonly (); <br/> // with limits <br/> entitymanager. find (query. withoffset (10 ). withlimit (100); <br/>