Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-01-27
2002-05-14
Corrielus, Jean M. (Department: 2172)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C709S217000, C709S218000, C709S220000, C709S223000
Reexamination Certificate
active
06389422
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of relaying a file object, a distributed file system, a computer readable medium recording a program of a method of relaying a file object, and to a gateway computer. More specifically, the present invention relates to a method of relaying a file object, a distributed file system, a computer readable recording medium, recording a program of a method of relaying a file object and a gateway computer, allowing reference of one same file object among networks.
2. Description of the Background Art
In a conventional distributed file system, a server computer stores replicas of file objects in a storage, that is, a cache. In response to an access request from a client computer, the server computer relays a replica of a file object stored in the cache to the client computer. By such a series of operations, the speed of accessing is improved. Such method has been know from Japanese Patent Laid-Open No. 4-313126 entitled “File Input/Output System for Decentralized File System”, and Japanese Patent Laid-Open No. 63-200244 entitled “File Access System”, Japanese Patent Laid-Open No. 63-201845 entitled “Remote File Access System”, for example. A computer used for such a method and performing the above described operation is generally referred to a as a gateway computer.
A typical example of the distributed file system is the internet which is a global network utilizing TCP/IP (Transmission Control Protocol/Internet Protocol). A distributed file system consisting of file objects in the form of hypertext formed utilizing Hypertext Transfer Protocol (HTTP) on the internet is referred to as a World Wide Web (WWW) system. In the WWW system, when a file object is transferred utilizing HTTP, relaying of a file object by the gateway computer, storing of a replica of the file object and relaying of the replica of the file object are widely performed. The gateway computer relaying the file object in the WWW system on the internet is generally referred to as Proxy server. Generally, the Proxy server is implemented by running a Proxy software on a computer connected to the network.
The file objects include not only simple text but also image, voice, video image and various other data, which are attractive both to providers and users of the information. This results in explosive flow of WWW system traffic on the network.
Further, a user uses a browser software having a graphical user interface installed in a client computer. This allows the user to successively access pieces of information consisting of file objects held by server computers distributed on the network. Because of this simplicity, today, the WWW system is enormously popular.
A file object is specified by a URL (Uniform Resource Locator). If the URL is “http://www. sharp co. jp/image/index.html”, the name of the server computer is “www.sharp.co.jp”, and a file “image/index.html” in a directory for the Web server in the server computer is designated.
Referring to
FIG. 36
, the conventional distributed file system includes a server computer
120
, a representative gateway computer
116
, a client computer
102
, a global network
132
, and a local network
112
. To global network
132
, server computer
120
and representative gateway computer
116
are connected. To the local network
112
, representative gateway computer
116
and client computer
102
are connected.
A browser
104
is in operation on client computer
102
. In accordance with an instruction from a user
100
, browser
104
transmits a request for a file object to representative gateway computer
116
, receives the file object and presents the file object to user
100
.
A Proxy
370
is in operation in representative gateway computer
116
. In response to a request for getting a file object transmitted from client computer
104
, Proxy
370
reads the file object from the server computer
120
or a cache
374
which will be described later, and transmits the read object to client computer
104
. Representative gateway computer
116
includes a cache
374
for storing a file object read from server computer
120
, and an access log
372
for storing record of reading (for example, date of reading) of a file object received from server computer
120
.
Server computer
120
includes a storage
376
for storing file objects.
Referring to
FIG. 37
, representative gateway computer
116
is a computer having a network interface, including a CPU (Central Processing Unit)
380
, a memory
382
, an I/O (Input/Output) unit
388
, a file device
390
and a network I/O unit
384
. These components of representative gateway computer
116
are coupled by an internal bus
386
. File device
390
is classified into a cache file
374
, a log file
372
and a unit storing other variables and so on.
Again referring to
FIG. 36
, a series of operations for getting a file object in the conventional distributed file system will be described.
A client computer
102
a
transmits a request for a file object to representative gate computer
116
for an access to a file object on an external network.
Proxy
370
which is a process (thread) operating in representative gate computer
116
receives the request.
Proxy
370
accesses cache
374
, and determines whether the corresponding file object exists in the cache
374
. When the file object is stored in cache
374
, Proxy
370
compares valid date thereof with time of change (modification) of the file object stored in cache
374
. If the valid date of the file object is not expired, Proxy
370
reads the file object from cache
374
, and transmits the file object to client computer
102
a.
If there is not a valid file object in cache
374
, that is, when the desired file object is absent or when the object is present but the valid date has already been expired, then Proxy
374
transmits a request for the file object to server computer
120
connected to global network
132
.
Upon reception of the request, server computer
120
reads the file object from storage
376
and transmits the file object to Proxy
370
. Proxy
370
which has received the file object transfers the file object to client computer
102
a
. Further, it writes the file object to cache
374
. At this time, HTTP header information of transfer, date of writing the file object and time and date of accessing are stored in log file
372
.
When another client computer
102
b transmits a request for getting the same file object to representative gateway computer
116
, Proxy
370
reads the file object from cache
374
and transmits it to client computer
102
b
. In this manner, as client computers
102
a
and
102
b
share cache
374
, it is possible for client computers
102
a
and
102
b
to take out a file object which is frequently requested, at a high speed.
It is possible to operate browser
104
and Proxy
370
simultaneously as separate processes, on a client computer
102
. One example of such a client computer
102
is disclosed in Japanese Patent Laid-Open No. 7-93205. Browser
104
on the client computer
102
transmits a request for a file object to Proxy
370
operating on client computer
102
itself In this case, the IP address for specifying a computer on which Proxy
370
is in operation is set to IP address
127
.
0
.
0
.
1
which designates the client computer itself. This enables simultaneous running of browser
104
and Proxy
370
on client computer
102
without any special change or modification to browser
104
.
The above described client computer
102
is generally implemented by a desktop computer. A desktop computer has state of the art high speed CPU, large storage memory, a well fitting keyboard with wide key pitch, a large display monitor and a hard disk of large capacity, as well as full specification satisfied only by the stationary computer.
The WWW system on the internet allows the above described method of accessing in which user
100
explicitly requests a specific file object stored in server computer
120
so that the file object is transferred to c
Doi Katsuo
Toda Hiroyoshi
Corrielus Jean M.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
LandOfFree
METHOD OF RELAYING FILE OBJECT, DISTRIBUTED FILE SYSTEM,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with METHOD OF RELAYING FILE OBJECT, DISTRIBUTED FILE SYSTEM,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and METHOD OF RELAYING FILE OBJECT, DISTRIBUTED FILE SYSTEM,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2901417