Patent Application
20050091405
The invention relates generally to distributed software systems and networks, and more particularly to using text-based encoding to transfer data objects across networks. Still more particularly, the invention relates to a method and system for using multiple data type representations to deliver data objects to components in a distributed system.
Recent and ongoing innovations in decentralized networks and distributed systems have resulted in the increased use of text-based encoding to transfer data objects across networks. A data object typically includes a collection of data items, and may also include behavior or code associated with particular data. In some programming languages, such as C++ and Java, a data object is also “typed.” The “type” of a data object specifies the data items that the object contains as well as the operations it can perform. A text representation of a data object is utilized to transfer the information in the data object over a network. Each node in a network must be able to convert the text representation into a format that can be used by one or more components residing within that node. Nodes typically include various types of computing devices.
a is a data flow diagram of a first type of data object conversion according to the prior art. A data object of a particular type (logical type 100) is converted to a native data type representation 102. A native data type representation refers to a native format, such as a native binary format, that is usable by the underlying software environment. One example would be the Java byte code that is executable on Java virtual machines. Each distinct type of data object can have its own unique binary representation, and a node in a distributed network includes instructions on how to represent the data objects in a native format.
Unfortunately, in a loosely coupled distributed network, such as a distributed measurement system, a receiving node within the network may be built and deployed before a sending node is produced. The newer sending node, when deployed, may contain new data object types not known to the existing nodes in the network. Consequently, the older receiving node may not include all of the necessary instructions to convert all of the logical types 100 received from the newer sending node into native data type representations 102. The older receiving node must be retrofitted with additional instructions in order to receive data objects from the newer sending node.
To avoid the need to retrofit nodes in a network, some distributed systems use a second type of data object conversion, which is shown in the data flow diagram of
The generic container data type representation 104, however, does not provide the same design capabilities and support that a native data type representation 102 provides, since the generic container data type representation 104 cannot be typed at compile time. Consequently, systems that support the generic container data type representation lose the ability for static type checking. Additionally, the same container type is used to represent multiple logical data types, so these systems cannot associate type-specific behavior with the containers.
In accordance with the invention, a method and system for using multiple data type representations to deliver data objects to components in a distributed system is provided. A node within a network receives a data object and generates a generic container data type representation. Data in the received data object are mapped into one or more fundamental data items, such as integers, floats, and bytes, and then placed within a container such as an array. The container data type representation is assigned an annotation, or identifier, based on the contents within the container. The node then determines whether a native data type representation that corresponds to the container data type representation is available on the node. If a native data type representation is available, the node transforms the container data type representation into a native data type representation and transmits the native data type representation to a component residing within the node.
In one embodiment in accordance with the invention, the node transmits the container data type representation to a component when a native data type representation does not exist within the node. In another embodiment in accordance with the invention, the node determines whether some or all of the data in the container data type representation can be transformed into an incomplete native data type representation when a native data type representation is not available. If data cannot be transformed into an incomplete native data type representation, the node transmits the container data type representation to a component. If, however, data can be transformed into an incomplete native data type representation, the node transforms the known data into the incomplete native data type representation. The node then transmits the incomplete native data type representation to a component residing within the node. The node may also transmit the container data type representation to the component along with the incomplete native data type representation.
The invention will best be understood by reference to the following detailed description of embodiments in accordance with the invention when read in conjunction with the accompanying drawings, wherein:
a is a data flow diagram of a first type of data object conversion according to the prior art;
b is a data flow diagram of a second type of data object conversion according to the prior art;
The invention relates to a method and system for using multiple type representations to deliver data objects to components in a distributed system. The following description is presented to enable one skilled in the art to make and use the invention, and is provided in the context of a patent application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments. Thus, the invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the appended claims and with the principles and features described herein.
With reference now to the figures and in particular with reference to
An instance of a generic container data type representation is created to hold the data objects, as shown in block 302. The container data type representation is then tagged with an annotation, or identifier, at block 304. The annotation in this embodiment in accordance with the invention is a human readable string to annotate the logical type the container data type represents. Containers that contain the same types and instances of data items are assigned identical annotations, while containers that contain different types and instances of data items are assigned different annotations. Using the annotation and the contents of the container, a determination is then made at block 306 as to whether the node has a native data type representation corresponding to the annotation and container content.
If the node does not have a corresponding native data type representation, the process passes to block 308 where the container data type representation is transmitted to a component within the node. A component includes any program or device that can access or utilize the data items within a container data type representation and/or a native data type representation. A component can elect to accept data in a container data type representation or in a native data type representation in this embodiment in accordance with the invention.
For example, in those embodiments in accordance with the invention where a component is able to act on a variety of data, a system designer may prefer the component accept data in a generic container data type representation. In other embodiments in accordance with the invention a component may be able to act on a specific type of data only, or it may require a behavior or code associated with a particular data. In these embodiments, a system designer may prefer a component accept data in a native data type representation.
Referring again to block 306, if the node does have a native data type representation that corresponds to the annotation and container content, a determination is made at block 310 as to whether a component within the node elects to receive the native data type representation. If not, the container data type representation is transmitted to the component at block 308. If, however, the component does elect to receive the native data type representation, the data fields in the container are extracted and transformed into a native data type representation (blocks 312 and 314). The native data type representation is then transmitted to a component at block 308.
Using the annotation and the contents of the container data type representation, a determination is then made at block 404 as to whether the node has a native data type representation corresponding to the annotation and container content. If the node has a native data type representation that corresponds to the annotation and container content, a determination is made at block 406 as to whether a component within the node has elected to receive the native data type representation. If not, the container data type representation is transmitted to the component at block 408. If, however, a component has elected to receive the native data type representation, the data fields in the container are extracted and transformed into the native data type representation (block 410). The native data type representation is then transmitted to the component (block 408).
Returning to block 404, if the node does not have a native data type representation that corresponds to the annotation and container content, a determination is made at block 412 as to whether the node knows some or all of the content in the container data type representation. Content is “known” by a node when some or all of the data fields can be transformed into an incomplete native data type representation. An incomplete native data type representation is a representation where all of the data fields in a native data type representation are not initialized. If the node does not know some or all of the content, the process passes to block 408 where the container data type representation is transmitted to a component.
If, however, the node does know some or all of the container content, a determination is made at block 414 as to whether a component elects to receive multiple data type representations. If a component does elect to receive multiple data type representations, all or part of the content that is known by the node is transformed to an incomplete native data type representation (block 416). The container data type representation continues to store all of the content in this embodiment in accordance with the invention. The multiple data type representations (i.e., the container data type representation and the incomplete native data type representation) are then transmitted to the component (block 408).
Returning again to block 414, if a component does not elect to receive multiple data type representations, a determination is made at block 418 as to whether the component prefers to receive an incomplete native data type representation. If the component does elect to receive an incomplete native data type representation, all or part of the container content that is known by the node is transformed to an incomplete native data type representation (block 420). The incomplete native data type is then transmitted to the component. If, however, the component does not prefer to receive an incomplete native data type representation, the container data type representation is transmitted to the component.
The invention, however, is not limited to the embodiments illustrated in
If the data is not held in a generic container data type representation, however, the process passes to block 504 where the data fields are extracted from the object. A generic container data type representation is created to hold the data and the container data type representation is annotated (blocks 506 and 508). The annotation in this embodiment in accordance with the invention is a human readable string to annotate the logical type the container data type represents. The container data type representation is then transmitted over a network (block 502).
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