com.vaadin.flow.server.

All Superinterfaces:

Serializable
```
public interface StreamVariable
extends Serializable
```
StreamVariable is a special kind of variable whose value is streamed to an OutputStream provided by the getOutputStream() method. E.g. in web terminals StreamVariable can be used to send large files from browsers to the server without consuming large amounts of memory.
Note, writing to the OutputStream is not synchronized by the handler (to avoid stalls in other operations when e.g. streaming to a slow network service or file system). If UI is changed as a side effect of writing to the output stream, developer must handle synchronization manually.

Since:

1.0.

Author:

Vaadin Ltd

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`StreamVariable.StreamingEndEvent` Event passed to `streamingFinished(StreamingEndEvent)` method the contents have been streamed to StreamVariable successfully.
`static interface`	`StreamVariable.StreamingErrorEvent` Event passed to `streamingFailed(StreamingErrorEvent)` method when the streaming ended before the end of the input.
`static interface`	`StreamVariable.StreamingEvent` Streaming event interface.
`static interface`	`StreamVariable.StreamingProgressEvent` Event passed to `onProgress(StreamingProgressEvent)` method during the streaming progresses.
`static interface`	`StreamVariable.StreamingStartEvent` Event passed to `streamingStarted(StreamingStartEvent)` method before the streaming of the content to `StreamVariable` starts.

Method Summary

All Methods
Modifier and Type	Method and Description
`OutputStream`	`getOutputStream()` Invoked when a new upload arrives, after `streamingStarted(StreamingStartEvent)` method has been called.
`boolean`	`isInterrupted()` If this method returns true while the content is being streamed the handler is told to stop receiving the current upload.
`boolean`	`listenProgress()` Whether the `onProgress(StreamingProgressEvent)` method should be called during the upload.
`void`	`onProgress(StreamVariable.StreamingProgressEvent event)` This method is called if `listenProgress()` returns true when the streaming starts.
`void`	`streamingFailed(StreamVariable.StreamingErrorEvent event)` This method is called when the streaming has failed.
`void`	`streamingFinished(StreamVariable.StreamingEndEvent event)` This method is called when the streaming has finished.
`void`	`streamingStarted(StreamVariable.StreamingStartEvent event)` This method is called when the streaming starts.

- Method Detail
  - getOutputStream
```
OutputStream getOutputStream()
```
    Invoked when a new upload arrives, after streamingStarted(StreamingStartEvent) method has been called. The implementation will write the streamed variable to the returned output stream.
    
    Returns:
    
    Stream to which the uploaded file should be written.
  - listenProgress
```
boolean listenProgress()
```
    Whether the onProgress(StreamingProgressEvent) method should be called during the upload.
    onProgress(StreamingProgressEvent) is called in a synchronized block when the content is being received. This is potentially bit slow, so we are calling that method only if requested. The value is requested after the streamingStarted(StreamingStartEvent) event, but not after reading each buffer.
    
    Returns:
    
    true if this StreamVariable wants to by notified during the upload of the progress of streaming.
    
    See Also:
    
    onProgress(StreamingProgressEvent)
  - onProgress
```
void onProgress(StreamVariable.StreamingProgressEvent event)
```
    This method is called if listenProgress() returns true when the streaming starts.
    
    Parameters:
    
    event - streaming progress event
  - streamingStarted
```
void streamingStarted(StreamVariable.StreamingStartEvent event)
```
    This method is called when the streaming starts.
    
    Parameters:
    
    event - streaming start event
  - streamingFinished
```
void streamingFinished(StreamVariable.StreamingEndEvent event)
```
    This method is called when the streaming has finished.
    
    Parameters:
    
    event - streaming end event
  - streamingFailed
```
void streamingFailed(StreamVariable.StreamingErrorEvent event)
```
    This method is called when the streaming has failed.
    
    Parameters:
    
    event - streaming error event
  - isInterrupted
```
boolean isInterrupted()
```
    If this method returns true while the content is being streamed the handler is told to stop receiving the current upload.
    Note, the usage of this method is not synchronized over the Application instance like other methods. The implementation should only return a boolean field and especially not modify UI or implement a synchronization by itself.
    
    Returns:
    
    true if the streaming should be interrupted as soon as possible.

com.vaadin.flow.server.

Interface StreamVariable

Nested Class Summary

Method Summary

Method Detail

getOutputStream

listenProgress

onProgress

streamingStarted

streamingFinished

streamingFailed

isInterrupted