Electrical computers and digital processing systems: multicomput – Computer-to-computer data modifying
Reexamination Certificate
1998-05-27
2001-08-07
Dinh, Dung C. (Department: 2756)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data modifying
C709S206000, C709S218000, C709S219000, C709S229000, C709S247000
Reexamination Certificate
active
06272549
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to computer systems and more particularly to the TCP/IP protocol for exchanging data between computer systems. Even more particularly, the invention relates to using electronic mail to enhance TCP/IP in exchanging data between computer systems.
BACKGROUND OF THE INVENTION
Data is often exchanged between two computer systems, particularly over the internet, using the Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP is integrated into the OSI reference model for networks wherein TCP performs the transport layer function and IP performs the network layer function. Because TCP/IP is a part of the normal network software contained within a computer system, direct use of TCP/IP will usually penetrate the firewall established for the computer system. Because of this, most computer systems are set up to not allow the direct use of TCP/IP within their computer systems, except for certain well known applications such as electronic mail, thus to avoid the penetration of the firewall by an unknown and untested application.
When communicating between computer systems, one can accept the penetration of the firewall and use TCP/IP directly, or find another solution which does not penetrate the firewall. One such solution is to use dial-up modems to establish a point-to-point link between the two computers. With this type of connection no other computer systems could attach to the link, therefore, there is no possibility of penetrating the firewall within either computer system. Using modems, however, increases the cost of the is connection, because of the additional cost of the modems plus the costs of the long distance telephone charges for each connection, when the connection is not a local connection. Using dial-up modems also increases the complexity of the connection, because of the necessity to either manually dial the telephone to make the connection, or provide software that performs the dialing and connecting processes, in addition to the original communication process.
Another problem with the prior art use of TCP/IP is that not all computer systems have this protocol available. If this protocol is not available on a computer system, then obviously it cannot be used to communicate with another computer system.
There is need in the art then for a communications system between two computers that avoids the complexity and costs of dial-up connections, while also avoiding the firewall penetration problems caused by direct TCP/IP connections. Still another need is for such a communications system that does not rely on TCP/IP being present in a computer system. The present invention meets these and other needs in the art.
SUMMARY OF THE INVENTION
It is an aspect of the present invention to perform the functions of the TCP/IP protocol using electronic mail.
It is another aspect of the invention to use existing TCP programming while replacing the IP programming with calls to an electronic mail server.
Yet another aspect of the invention is to perform the protocol while executing within a user address space.
Still another aspect of the invention is to convert data between binary and ASCII, so that only ASCII is sent through electronic mail.
The above and other aspects of the invention are accomplished in a TCPEmail system that builds an additional TCP/IP protocol layer on top of an electronic mail system. Although the electronic mail system may use the conventional TCP/IP protocol to communicate between computers, and thus, penetrates the firewall, e-mail is a commonly accepted process and is allowed to penetrate the firewall in most computer systems. Many corporations today severely limit the exchange of TCP/IP traffic but place little or no restrictions on electronic mail, so TCPEmail can connect processes that would otherwise not be able to make use of interprocess communication.
An application program that wishes to communicate to another computer uses TCPEmail in the conventional manner of using TCP/IP, except that TCPEmail runs within the user address space, rather than the system address space where the conventional TCP/IP process runs. Because the TCPEmail process runs in user address space, the process must allocate its own memory from the user space and manage the use of the allocated memory.
When an application program wishes to send data through TCPEmail, it calls TCPEmail and passes it the data to be sent. The TCP process within TCPEmail breaks the data into packets and calls the IP process within TCPEmail to send each of these packets. The IP portion of TCPEmail receives the packet, converts it into ASCII format, since binary data cannot be transmitted through electronic mail, and then calls the electronic mail system to send the packet as a conventional electronic mail message.
When an electronic mail message is received by TCPEmail, it converts the ASCII data within the mail message into a binary data packet, and sends this packet to the TCP portion of TCPEmail as a conventional TCP packet. The TCP portion of the TCPEmail system combines the packets from several messages, and delivers the data to the application as received data. Because TCPEmail uses standard electronic mail to send and receive data, and because standard electronic mail is typically slower than communications that directly use TCP/IP, the time-outs for receiving acknowledgments of packets sent must be extended when using TCPEmail.
REFERENCES:
patent: 5136291 (1992-08-01), Teague
patent: 5673322 (1997-09-01), Pepe et al.
patent: 5710883 (1998-01-01), Hong et al.
patent: 5912697 (1999-06-01), Hashimoto et al.
Freed & Borenstein (Multipurpose Internet Mail Extensions, Nov. 1996.)*
Jonathan B. Postel (Simple Mail Transfer Protocol, Nov. 1981).*
Freed & Borenstein (Multipurpose Internet Mail Extensions, Nov. 1996).*
Johathan B. Postel (Simple Mail Transfer Protocol, Nov. 1981).*
Comer, Douglas E. and Stevens, David L.,Internetworking with TCP/IP Volume II Design, Implementation, and Internals, Prentice-Hall, Inc. 1994, Chapters 11, 12, 13, pp. 191-268.
Dinh Dung C.
Hewlett -Packard Company
Ho Chuong
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