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https://issues.apache.org/jira/browse/THRIFT-1948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13644803#comment-13644803
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Jens Geyer commented on THRIFT-1948:
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{quote}
The current list requires the knowledge of the number of items a priori. This
would allow the elements to be written as they are read.
{quote}
Not necessarily. You can make as many calls as you want. I should have written
"one element per call" to make things more clear, but the intention was to
leave the possibility for grouping more than one element in one call (and that
certainly would have been the next response then, right? :-)).
> Add a stream type
> -----------------
>
> Key: THRIFT-1948
> URL: https://issues.apache.org/jira/browse/THRIFT-1948
> Project: Thrift
> Issue Type: New Feature
> Components: AS3 - Compiler, AS3 - Library, C glib - Compiler, C glib
> - Library, C# - Compiler, C# - Library, C++ - Compiler, C++ - Library, Cocoa
> - Compiler, Cocoa - Library, Compiler (General), D - Compiler, D - Library,
> Delphi - Compiler, Delphi - Library, Erlang - Compiler, Erlang - Library, Go
> - Compiler, Go - Library, Haskell - Compiler, Haskell - Library, Java -
> Compiler, Java - Library, JavaME - Compiler, JavaME - Library, JavaScript -
> Compiler, JavaScript - Library, Node.js - Compiler, Node.js - Library, OCaml
> - Compiler, OCaml - Library, Perl - Compiler, Perl - Library, PHP - Compiler,
> PHP - Library, Python - Compiler, Python - Library, Ruby - Compiler, Ruby -
> Library, Smalltalk - Compiler, Smalltalk - Library
> Reporter: Carl Yeksigian
> Assignee: Carl Yeksigian
>
> This is a proposal for an addition to the Thrift IDL, which allows for
> sending chunks of data between the server and the client without having the
> whole message in memory at the start of the communication.
> The new keyword, "stream<T>", would indicate that there is a series of values
> typed T which would be communicated between client and server. Stream would
> have three primitives:
> {code}
> next(T)
> error(TException)
> end()
> {code}
> Protocols would be enhanced with the following methods:
> {code}
> writeStreamBegin(etype, streamid)
> writeStreamNext(streamid, streamMessageType)
> writeStreamNextEnd()
> writeStreamErrorEnd()
> etype, streamid = readStreamBegin()
> streamid, streamMessageType = readStreamNext()
> readStreamNextEnd()
> readStreamErrorEnd()
> {code}
> streamMessageType is one of the following:
> # next
> This means that the message will be of the element type.
> # error
> An exception was thrown during materialization of the stream.
> The stream is now closed.
> # end
> This means that the stream is finished.
> The stream is now closed.
> Once all streams are closed, readMessageEnd should be called. Before the
> first writeStreamNext() could be called, the message should otherwise be
> complete. Otherwise, an exception should be raised.
> It is possible that an exception will be thrown while the stream is being
> materialized; however, this can only occur inside of a service. In this case,
> error() will be called; the exception should be one of the exceptions that
> the service call would have thrown. The values that were generated before the
> exception will generally be valid, but may only have meaning if the stream is
> ended. All streams which are currently open may get the same exception.
> If the following service was defined:
> {code}
> stream<i64> random_numbers(stream<i64> max)
> {code}
> A sample session from client to server would be:
> {code}
> writeMessageBegin()
> writeStreamBegin(I64, 0)
> writeStreamNext(0, next)
> writeI64(10)
> writeStreamNextEnd()
> writeStreamNext(0, end)
> writeMessageEnd()
> {code}
> A sample session from server to client would be:
> {code}
> writeMessageBegin()
> writeStreamBegin(i64, 0)
> writeStreamNext(0, next)
> writeI64(3)
> writeStreamNextEnd()
> writeStreamNext(0, end)
> writeMessageEnd()
> {code}
> This change would not be compatible with previous versions of Thrift. Also,
> for languages which do not support this type of streaming, it could be
> translated into a list.
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