Google App Engine的云端点在哪里？

Question

I'm working on a project which uses the Google App Engine to store application data remotely. So far, I've created a simple class GenericEntity and used Google's tools to generate a supporting Cloud Endpoint.

@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class GenericEntity {

/* Define the UniqueID as persistent and unique. Allow JDO to assign the value of UniqueId when uploaded with a null id. */
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@GeneratedValue(strategy = GenerationType.AUTO)
private Long mUniqueId; // Value must be 'Long' and not a primitive 'long'!

@Persistent
private String mData;
[...]

I can also successfully create and delete instances of GenericEntity in the GenericEntityEndpoint using the API Explorer.

Request:

POST 

Content-Type:  application/json
X-JavaScript-User-Agent:  Google APIs Explorer

{
"data": "hello SO!"
}

Response:

200 OK

The issue is that I would like to control these endpoints from a local Desktop application, but I'm confused as to how this is supposed to be done. I imagine that the PersistenceManagerFactory is local only to Google's servers, and subsequently can't be accessed directly by my application. Is there a final step I'm missing which will allow high-level interaction with these generated Endpoints over a network, or do I need to implement my own interface with the server using HttpUrlRequest functions?

Answer 1

Cloud endpoint sends JSON data using REST or RPC over HTTP and authentication is managed using OAuth2 so you can either write your desktop application from scratch or you can use the various Google libraries to connect to your endpoint. For Java applications I usually use the Android cloud endpoint library which you can generate using the endpoint.sh, I use the classes generated for Android to call the cloud endpoint from any other Java apps:

appengine-java-sdk-x.x.x/bin/endpoints.sh <command> <options> [class-name]

more details here ( https://cloud.google.com/appengine/docs/java/endpoints/endpoints_tool )

Once the source jar is generated by endpoint.sh I usually expand it into my client Java project. Otherwise you can compile the generated classes and bundle them as a binary jar. Once this is done you need to take care of the authentication part. This can be done by using the OAuth2 Java client library ( https://developers.google.com/api-client-library/java/apis/oauth2/v1 ) see the provided example oauth2-cmdline-sample

Once you have an OAuth2 token calling the cloud endpoint form your desktop application is no different to calling any other Google API, the Service Object and Builder patterns are all the same eg depending on the name of your endpoint API you can create a service object from the endpoint.sh generated classes as follows

Endpoint endpoint = Endpoint.Builder(
                        HTTP_TRANSPORT, JSON_FACTORY, getCredential()).build();