Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output data buffering
Reexamination Certificate
1998-07-21
2001-01-23
Lintz, Paul R. (Department: 2768)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output data buffering
C710S001000, C710S107000, C710S022000, C711S162000, C711S148000, C711S133000, C711S100000
Reexamination Certificate
active
06178471
ABSTRACT:
TECHNICAL FIELD
The present invention is generally directed to transfers of data in a streaming environment and, in particular, to a more efficient method for transferring such data.
BACKGROUND OF THE INVENTION
A variety of applications advantageously perform transfers of data in a so-called “streaming” environment. In general, such transfers are accomplished with a series of modules that sequentially operate to pass data from an inbound stream (i.e., a “read” stream) to an outbound stream (i.e., a “write” stream), in this way moving the data along the prescribed stream. Such transfers of data are useful in applications including web servers (i.e., “exit” routines), servlet extensions (i.e., a potentially emerging Internet model), and other streaming environments having equivalent functionality. In practice, however, such methods have been found to exhibit certain limitations.
For example, one known practice for implementing a streaming environment is to use a basic (i.e., “trivial”) approach in which data is exhaustively obtained from the read stream (or read “pipe”) and then written to the write stream (or write “pipe”). This process is then followed by the writing of any new data to the write stream (i.e., down the write pipe). This solution has the disadvantage, however, that all transferred data must be copied from the read pipe to the write pipe for each of the transfers made between the plural modules which comprise the data transfer system. This leads, in turn, to an adverse system overhead which limits the efficiency and, accordingly, the overall data transfer rate that can be established using such a system.
Another known practice for implementing a streaming environment is used with CMS (conversational monitor system) pipelines. In conjunction with the operation of a CMS pipeline, a method (i.e., the so-called “SHORT” method) is provided that allows a given stage of the pipeline to connect the inbound stream directly to the outbound stream. Although this method helps to increase the efficiency of the resulting system, such a method lacks the ability to append data to the outbound stream after the data received from the inbound stream has been exhausted.
Also to be considered is that the model used by CMS pipelines is record based and, therefore, quite different from the desired model in which data is to be sequentially transferred in a way that minimizes the performance and system resource penalties associated with the copying of data as that data is transferred from module to module. Further, after exhausting its read source, each module must have the ability to write to the outbound pipe.
Therefore, the primary object of the present invention is to provide a module useful in a streaming environment that can pass data from the inbound stream to the outbound stream in a way that minimizes the performance and resource penalties associated with the copying of data. Another object of the present invention is to provide a module useful in a streaming environment that can efficiently pass data from the inbound stream to the outbound stream and that has the ability to return control to the module during the data transfer function. Still another object of the present invention is to provide a module useful in a streaming environment that can efficiently pass data from the inbound stream to the outbound stream and which, after exhausting the read source, has the ability to write additional data to the outbound pipe.
SUMMARY OF THE INVENTION
These and other objects which will become apparent are achieved in accordance with the present invention by slaving downstream buffer objects with the immediate upstream buffer object using the so-called “write remaining” method which is conventionally associated with each module. The write remaining method is invoked from each module having access to the read and write pipes, and operates to slave not the data, but wrappers that point to the data and which in this way represent references to a single copy of the data stored as an upstream data buffer object.
This method has the benefit of allowing the actual data to exist in only one place after the write remaining method has been invoked, rather than requiring the data to be sequentially copied from one data buffer to the next. This method further has the benefit of allowing control to be returned to the module during the data transfer function, and of allowing additional data to be written to the outbound pipe.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.
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Barrett Robert C.
Howland Michael J.
Pritko Steven M.
International Business Machines - Corporation
Lintz Paul R.
Ratner & Prestia
Samodovitz Arthur J.
Speight Jibreel
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