Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network access regulating
Reexamination Certificate
1999-04-09
2003-11-25
Coulter, Kenneth R. (Department: 2142)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network access regulating
C709S202000, C709S207000, C709S223000, C709S247000
Reexamination Certificate
active
06654806
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of computer software. More specifically, the invention relates to a method and apparatus for adaptably providing data to a network environment.
Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyrights whatsoever. Sun, Sun Microsystems, the Sun logo, Solaris, SPARC, “Write Once, Run Anywhere”, Java, JavaOS, JavaStation and all Java-based trademarks and logos are trademarks of Sun Microsystems, Inc. in the United States and in other countries.
BACKGROUND
A computer network is sometimes used to deliver streams of data (such as video data) to one or more computers on a network. The video data can be presented at different levels of quality, with higher quality meaning larger amounts of data needs to be transmitted. Different receiving computers may not be capable of displaying the same quality of data. Currently there is no effective way of sending video data with different levels of quality to different receiving computers. The problem can be understood by reviewing current networks and schemes for data transmission.
Networks Generally
A network is an amalgamation of interconnected computers. Computational devices properly connected to the network may utilize the network to communicate with other devices that are coupled to the network. A computational service provider computer, for example, may use a network to transmit a video data stream to a client computer for display. There are a variety of different techniques for propagating data to devices connected to the network. For example, data may be sent from a source computer to a destination computer, broadcast from one computer to all other computers on the network, or sent from a source computer to a select group of destination computers. Each of these methods is inherently limited in its ability to adequately balance the needs of the user with the performance characteristics of the network. For example, current data dissemination techniques do not provide a way to ensure data is displayed only to an intended recipient while also taking into account the characteristics of the network link that may affect transmission of the data to be displayed. Current methods for propagating data throughout a network lack a scheme for explicitly authorizing users to connect to a particular data stream and also do not provide a way to effectively control the quantity and quality of data transmitted to the user. A general discussion of the existing techniques for sending data across a network and the problems associated with using such methods follows.
Unicasting
Sending data from a source computer to a single destination computer is called unicasting. This is the standard form of service provided by networking protocols such as the Transmission Control Protocol (TCP). TCP is a connection-oriented transport protocol designed to provide network functionality to the user. TCP typically works in collaboration with other protocols such as the Internet Protocol (IP) and Media Access Control (MAC), protocols such as Ethernet in order to provide the user with network services. When data is transmitted from one location to another location using TCP the data is placed into packets (e.g. datagrams). Each packet of data is assigned a source address and a destination address. The source address indicates which computer is responsible for sending the data and the destination address indicates which computer is to receive the data that is sent.
Referring now to
FIG. 1
an example of unicasting is illustrated. Network nodes
101
-
105
are five separate computational devices. Personal computers and network equipment such as routers, switches, and/or hubs are examples of network nodes
101
-
105
. Other devices such as laptops and Personal Desktop Assistants (PDAs) may also function as network nodes
101
-
105
.
Network nodes
101
-
105
may transmit data to network nodes
151
-
154
using network
125
. In some cases, network
125
achieves connectivity by using the Internet. The Internet is a global computer network comprised of numerous other networks that are all capable of communicating with one another using a standardized set of protocols. In other instances network
125
is representative of a wide area network or any other type of data transmission medium that allows nodes
101
-
105
to communicate with nodes
151
-
154
.
Unicasting enables a data source to transmit data to a data destination. The data source is the device tasked to send the data and the data destination is the device the data is directed to. If, for example, network node
103
transmits data to network node
154
using path
120
, then network node
103
is the data source and network node
154
is the data destination. If, however, network node
154
sends data back to network node
103
, then network node
154
becomes the data source and network node
103
becomes the data destination. Data that is unicast may also be sent between two computers residing on the same network. For example, network node
101
may send data to and receive data from network node
105
. In this situation, data is not transmitted through network
125
but is sent using path
121
.
A problem with unicasting is that is does not allow for the efficient transfer of data to multiple computers. If, for example, a user were to want to display a video on a group of recipient nodes that user would have to send individual copies of the video to each recipient. Sending multiple copies of the same file to each recipient utilizes additional processor resources on the transmitting node and wastes network resources. In such situations, the amount of users that may receive data is constrained by the amount of bandwidth available. Unicasting does not provide a way to control the quantity and quality of data sent to the user. Additionally, unicasting schemes generally lack a mechanism for authorizing users to connect to a particular data stream.
Broadcasting
Another technique used for distributing data is referred to as broadcasting. When data is broadcast, it is sent to every node connected to the network. Broadcast services are typically provided by low-level network layer protocols such as the Internet Protocol (IP). Data that is broadcast is sent in a uniform data format. For example, a video broadcast may be sent to all recipients using the MPEG-2 data format. Receiving nodes that lack the ability to processes MPEG-2 data cannot display the broadcast. Thus, a problem with broadcasting is that each recipient is confined to utilizing a particular data format.
Referring now to
FIG. 2
an example of broadcasting is illustrated. A problem with broadcasting is that data is sent to every node on the network, regardless of whether the node is interested in receiving the broadcast. For example, if node
205
begins broadcasting data all remaining nodes
201
-
204
on network
200
receive the broadcast data. Each remaining node
201
-
204
is required to perform some processing in order to determine whether it is interested in the broadcast data.
Broadcast data may be confined to a certain portion of a network (e.g. a subnet or a LAN). For example, data broadcast using path
220
may be confined to network
200
and not transmitted to network
250
via network
268
. When this is done network nodes
251
-
256
do not receive or process any data related to the broadcast. However, even localized broadcasts are undesirable because they still require all nodes on the subnet performing the broadcasting to perform some processing in order to determine whether or not it is interested in the broadcast data. Thus, broadcasts do not provide a way to efficiently allocate network resources based upon a network's characteristics. Broadcasting does not provide a way to control the quantity and qu
Hanko James G.
Northcutt J. Duane
Ruberg Alan T.
Wall Gerard A.
Coulter Kenneth R.
Kang Paul H.
O'Melveny & Myers LLP
Sun Microsystems Inc.
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