Carl Yeksigian created THRIFT-1948:
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Summary: 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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