com.google.appengine.api.backends
Interface BackendService

public interface BackendService

BackendService allows you to retrieve information about backend servers. Backend servers are long running addressable servers that can be used for applications that need to keep persistent state in ram between requests.

This API allows you to retrieve information about the backend handling the current request. It also allows you to to get the address of a specific backend instance in such a way that a local server is used during development and a production server is used in production.

Field Summary

static java.lang.String	BACKEND_ID_ENV_ATTRIBUTE Environment attribute key where the backend name is stored.
static java.lang.String	DEVAPPSERVER_PORTMAPPING_KEY
static java.lang.String	INSTANCE_ID_ENV_ATTRIBUTE Environment attribute key where the instance id is stored.
static java.lang.String	REQUEST_HEADER_BACKEND_REDIRECT
static java.lang.String	REQUEST_HEADER_INSTANCE_REDIRECT

Method Summary

java.lang.String	getBackendAddress(java.lang.String backend) Get the address of a specific backend in such a way that a local server is used during development and a production server is used in production.
java.lang.String	getBackendAddress(java.lang.String backend, int instance) Get the address of a specific backend instance in such a way that a local instance is used during development and a production server instance is used in production.
java.lang.String	getCurrentBackend() Get the name of the backend handling the current request.
int	getCurrentInstance() Get the instance handling the current request.

Field Detail

REQUEST_HEADER_BACKEND_REDIRECT

static final java.lang.String REQUEST_HEADER_BACKEND_REDIRECT

See Also:

Constant Field Values

REQUEST_HEADER_INSTANCE_REDIRECT

static final java.lang.String REQUEST_HEADER_INSTANCE_REDIRECT

See Also:

Constant Field Values

INSTANCE_ID_ENV_ATTRIBUTE

static final java.lang.String INSTANCE_ID_ENV_ATTRIBUTE

Environment attribute key where the instance id is stored.

See Also:

getCurrentInstance(), Constant Field Values

BACKEND_ID_ENV_ATTRIBUTE

static final java.lang.String BACKEND_ID_ENV_ATTRIBUTE

Environment attribute key where the backend name is stored.

See Also:

getCurrentBackend(), Constant Field Values

DEVAPPSERVER_PORTMAPPING_KEY

static final java.lang.String DEVAPPSERVER_PORTMAPPING_KEY

See Also:

Constant Field Values

Method Detail

getCurrentBackend

java.lang.String getCurrentBackend()

Get the name of the backend handling the current request.

Returns:

The name of the backend or null if the request is not handled by a backend.

getCurrentInstance

int getCurrentInstance()

Get the instance handling the current request.

Returns:

The instance id or -1 if the request is not handled by a backend.

getBackendAddress

java.lang.String getBackendAddress(java.lang.String backend)

Get the address of a specific backend in such a way that a local server is used during development and a production server is used in production.

Parameters:

backend - The name of the backend

Returns:

The address of the backend

getBackendAddress

java.lang.String getBackendAddress(java.lang.String backend,
                                   int instance)

Get the address of a specific backend instance in such a way that a local instance is used during development and a production server instance is used in production.

Parameters:

backend - The name of the backend

instance - The instance id

Returns:

The address of the backend instance