RequestT
- type of message sent one or more times to the server.ResponseT
- type of message received one or more times from the server.public abstract class ClientCall<RequestT,ResponseT> extends Object
Instances are created
by a Channel
and used by stubs to invoke their remote behavior.
More advanced usages may consume this interface directly as opposed to using a stub. Common reasons for doing so would be the need to interact with flow-control or when acting as a generic proxy for arbitrary operations.
start(io.grpc.ClientCall.Listener<ResponseT>, io.grpc.Metadata.Headers)
must be called prior to calling any other methods.
No generic method for determining message receipt or providing acknowledgement is provided. Applications are expected to utilize normal payload messages for such signals, as a response naturally acknowledges its request.
Methods are guaranteed to be non-blocking. Implementations are not required to be thread-safe.
Modifier and Type | Class and Description |
---|---|
static class |
ClientCall.Listener<T>
Callbacks for receiving metadata, response messages and completion status from the server.
|
Constructor and Description |
---|
ClientCall() |
Modifier and Type | Method and Description |
---|---|
abstract void |
cancel()
Prevent any further processing for this ClientCall.
|
abstract void |
halfClose()
Close the call for request message sending.
|
boolean |
isReady()
If
true , indicates that the call is capable of sending additional messages
without requiring excessive buffering internally. |
abstract void |
request(int numMessages)
Requests up to the given number of messages from the call to be delivered to
ClientCall.Listener.onMessage(Object) . |
abstract void |
sendMessage(RequestT message)
Send a request message to the server.
|
abstract void |
start(ClientCall.Listener<ResponseT> responseListener,
Metadata.Headers headers)
Start a call, using
responseListener for processing response messages. |
public abstract void start(ClientCall.Listener<ResponseT> responseListener, Metadata.Headers headers)
responseListener
for processing response messages.responseListener
- receives response messagesheaders
- which can contain extra call metadata, e.g. authentication credentials.IllegalStateException
- if call is already startedpublic abstract void request(int numMessages)
ClientCall.Listener.onMessage(Object)
. No additional messages will be delivered.
Message delivery is guaranteed to be sequential in the order received. In addition, the listener methods will not be accessed concurrently. While it is not guaranteed that the same thread will always be used, it is guaranteed that only a single thread will access the listener at a time.
If it is desired to bypass inbound flow control, a very large number of messages can be
specified (e.g. Integer.MAX_VALUE
).
numMessages
- the requested number of messages to be delivered to the listener.public abstract void cancel()
cancel()
ed or halfClose()
d.public abstract void halfClose()
IllegalStateException
- if call is already halfClose()
d or cancel()
edpublic abstract void sendMessage(RequestT message)
message
- message to be sent to the server.IllegalStateException
- if call is halfClose()
d or explicitly cancel()
edpublic boolean isReady()
true
, indicates that the call is capable of sending additional messages
without requiring excessive buffering internally. This event is
just a suggestion and the application is free to ignore it, however doing so may
result in excessive buffering within the call.
This implementation always returns true
.