FR2811098A1 - Procedure for transfer of electronic documents in a communication network, uses predictions of times when data transfer rates will be maximum to decide when to send data, based on measurement of previous transfers - Google Patents

Abstract

The communication procedure generates predicted values of the data transfer rate between a server and a client at different times within a predetermined future interval. These predicted transfer rates are then used in conjunction with transfer efficiency criteria to decide when to send the document. Records of performance of previous transfers are stored and used to make the predictions.

Description

The present invention relates to the field of communication networks.

  computers in which electronic documents are exchanged between computer systems linked via a network. The invention relates to a method for transferring an electronic i15 document from a server station to a client station, said stations being connected by a communication network. The invention relates more particularly, on the one hand, to a method of determining at least one date on which to effect the transfer of an electronic document; and secondly, a method of obtaining at least one date on which to transfer a document

electronic.

  The invention also relates to devices suitable for

the above processes.

  In the context of the present invention, the concept of "date" for effecting a transfer is understood to be a determined instant in time for

  perform the transfer, this moment can be expressed in the form of a date -

  expressed for example in the form: day of the week, calendar in the month, and time - or in the form of a delay relative to a date or a

moment in time.

  In computer communication networks are connected numerous computer systems, such as personal computers, and processing peripherals, such as printers, storage units, means for acquiring, processing or storing images or other types of documents. The present invention applies more particularly to communication networks which define a communication protocol allowing the computers and peripherals implementing this protocol,

  to exchange electronic documents.

  "Electronic document" means a set of data

  which can be very varied in nature: text, image, video, sound file.

  These networks use the principle known as "client-

  server "for the exchange of information between computer systems, designated here by the general term" station ". According to this principle, a station called" client "transmits a request for transfer of an electronic document to a station called "server" that hosts or is associated with a computer that

hosts the requested document.

  Client stations can be user systems, while server stations can be network servers dedicated to providing documents. However each of the stations of the network considered can

  be also, depending on the direction of the transfer, "clients" or "servers".

  Generally, there is a more or less long time between the moment when a user requests to download from his computer a document hosted on another computer or processing device, and the moment when this document is actually available on his computer . This time, called "transfer time", depends on the size of the communication network, the bandwidth available on the computer link which connects the user's computer to the network, the bandwidth available on the computer link which connects this network to the computer where the requested document, capacity and workload of the computer server are stored

  associated with this computer and the size of the requested document.

  The transfer time of an electronic document is therefore variable according to the capacity and state of congestion of the network as well as according to the workload of the server responsible for providing the requested document. Once triggered, the total download of a document may therefore require a more or less long time. When this time is long, it can be a source of loss of time for the user who must wait until the document has finished loading before he can use it. On the other hand, the longer the download time, the greater the risk of a network failure occurring during the download, which would force the user to

  rephrase later a request to download the same document.

  Furthermore, the greater the download time, the greater the connection time to the server, which increases the financial cost of connecting to the network and / or to the server, when this cost is recognized in

  depending on the duration of the connection.

  Consequently, there is a real need to have an electronic document transfer system in a communication network, which makes it possible to reduce document transfer times, so as to

  minimize the disadvantages mentioned above.

  The present invention aims to meet the need expressed above. To this end, according to a first aspect, the invention relates to a method for determining at least one date on which to carry out the transfer of an electronic document from a server station to a client station via a communication network, the method being implemented in the server station upon reception by the latter of a request for transfer of a document sent by the client station, the method being characterized in that it comprises the following steps: - generating predicted values transfer rate, between the server station and the client station, at a plurality of dates within a first predetermined period of time in the future; - determine from at least the predicted transfer rate values, at least one date, within the first predetermined period of time, to which the document can be transferred according to a criterion

  predetermined transfer efficiency.

  The method described above makes it possible, by predicting the available bit rate between the server and the requesting client station over a predetermined period of time in the future, to determine at least one future date for carrying out the transfer of the document under conditions allowing meet a transfer efficiency criterion. In practice, this criterion mainly consists in minimizing the duration of the document transfer. By planning the transfer on such a date, we will be able to minimize the drawbacks, mentioned above, relating to the duration of the transfer and the risks of breakdown.

associated network.

  According to a preferred embodiment of the invention, the step of generating the predicted values is preceded by a step of generating and storing first data representative of the transfer rate available during previous document transfers, between the server station and at least one client station in the network, at a plurality of dates within a second predetermined period of time in the past, the transfer rate predicted values being generated from said first data. In this way, a prediction of the transfer rate available in the future is made, based on real values of the rate of

  transfer observed in the past.

  According to an advantageous characteristic of the invention, the method of determining at least one date on which to effect the transfer of an electronic document comprises, before the step of determining at least one date within the first predetermined period of time, the following steps: - generating and storing second data representative of the workload of the server station measured at the plurality of dates within the second predetermined period of time in the past; - generate, from said second data, predicted values of workload of the server station, at the plurality of dates to

  within the first predetermined period of time.

  Said at least one date, within the first predetermined period of time in the future, to which the document can be transferred, is then determined according to the predicted throughput values of

  transfer and predicted workload values.

  The prediction of the workload of the server station within the same future period of time as for the prediction of the speed, makes it possible to guarantee a shorter transfer time of the document, during the transfer on the determined future date, insofar as the workload of the

  server influences the duration of a document transfer.

  According to a preferred embodiment of the invention, the method for determining at least one date on which to carry out the transfer of a document also comprises the following two steps: - send information indicative of said to the client station

minus a specific date.

  - receive from the client station, information indicative of a date chosen from said at least one determined date, the date chosen being

  date on which the document will be transferred.

  Thanks to this characteristic, we offer the possibility to the user-

  client station or person using the station - choose the final date on which the transfer will be made. This results in greater flexibility in the choice of transfer date, for better efficiency in

  transfer and for a better comfort of use.

  According to a second aspect, the invention relates to a method for obtaining at least one date on which to transfer an electronic document from a server station to a client station via a communication network, the method being implemented in the station. client, the method being characterized in that it comprises the following steps: - send to the server station a first request to transfer a document; receive from the server station information indicative of at least a future date; - select a date from said at least a future date;

  - receive the document from the server station on the selected date.

  This method allows planning, in the client station, of a future transfer date, depending, for example, on the availability of the client station and / or of the user of the client station. In connection with a server station in which a method according to the invention for determining the transfer date is implemented, this planning of the transfer makes it possible to

  minimize the document transfer time.

  According to a preferred embodiment, the step of selecting a date comprises the following sub-steps: - consulting a memory, in which are stored dates of availability of the client station and / or of the user of the station client; - compare the dates stored in the memory with said at

minus a future date.

  According to a preferred embodiment of the invention, this method further comprises, between the step of selecting a date and the step of receiving the document, the following step: - activating an alarm intended to trigger, the selected date,

  sending a second request to transfer said document to the server station.

  The invention also relates, in association with the methods set out above, to a method of transferring an electronic document from a server station to a client station, the stations being connected by a communication network, characterized in that it comprises: - implemented in the server station, the steps of a method for determining at least one date on which to carry out the transfer of an electronic document, in accordance with the present invention; - implemented in the client station, the steps of a method for obtaining at least one date on which to transfer an electronic document,

  in accordance with the present invention.

  Correlatively, the invention also relates to a device for determining at least one date on which to carry out the transfer of an electronic document from a server station to a client station via a communication network, the device being characterized in that it comprises: means for generating predicted values of transfer rate, between the server station and said client station, at a plurality of dates within a first predetermined period of time in the future; - means for determining from at least said predicted transfer rate values, at least one date, within the first predetermined period of time, to which the document can be transferred

  according to a predetermined transfer efficiency criterion.

  According to a preferred embodiment of the invention, the device comprises means for generating and storing first data representative of the transfer rate available during the transfer of documents, between the server station and at least one client station in the network, a plurality of dates within a second predetermined period of time in the past, the transfer rate predicted values being generated from

of said first data.

  According to an advantageous characteristic, this device comprises - means for generating and storing second data representative of the workload of the server station measured on the plurality of dates within the second predetermined period of time; means for generating, from said second data, predicted values of the workload of the server station, at the plurality of

  dates within the first predetermined period of time in the future.

  Said at least one date, within the first predetermined period of time in the future to which the document can be transferred, is then determined according to the predicted throughput values of

  transfer and predicted workload values.

  The invention also relates to a device for obtaining at least one date on which to transfer an electronic document from a server station to a client station via a communication network, the device being characterized in that it comprises - means to send a first document transfer request to the server station; means for receiving from the server station information indicative of at least one future date; - means for selecting a date from said at least one future date; means for receiving the document from the server station at the

selected date.

  According to a preferred embodiment, the device comprises: - a memory, in which are stored dates of availability of the client station and / or of the user of the client station - means for comparing the dates stored in the memory

  with said at least a future date.

  According to a preferred embodiment, the device comprises: - alarm means intended to trigger, on the selected date, the sending to the server station of a document transfer request; - means to activate the alarm means on the selected date. In association with the aforementioned devices, the invention also relates to a device for transferring an electronic document from a server station to a client station, the stations being connected by a communication network, characterized in that it comprises: - a device for determining at least one date on which to carry out the transfer of an electronic document, in accordance with the present invention; and - a device for obtaining at least one date to which to transfer

  an electronic document, in accordance with the present invention.

  The invention also relates to a server station connected to a communication network, characterized in that it comprises a device for determining at least one date on which to carry out the transfer of a

  electronic document, in accordance with the invention.

  The invention is correspondingly aimed at a client station connected to a communication network, characterized in that it comprises a device for obtaining at least one date on which to transfer an electronic document,

in accordance with the invention.

  The invention also relates to a communication network comprising at least one client station in accordance with the invention, and at least one

  server station in accordance with the invention.

  The invention also relates to a computer comprising means suitable for implementing the method or methods according to the invention as set out above. The invention also relates to a computer program comprising one or more sequence of instructions capable of implementing the method or methods according to the invention as set out above, when this program is executed by

a computer.

  The invention also relates to an information medium, such as a floppy disk or a compact disc (CD), characterized in that it contains such

computer program.

  The advantages of these devices, stations, this computer, this computer program, and this information medium are identical to those

  methods as succinctly set out above.

  Other features and advantages of the invention will become apparent

  again in the description below. In the accompanying drawings given as

non-limiting examples:

  - Figure 1 illustrates the general architecture of a communication network

  information adapted to implement the invention; - Figure 2 shows a typical example of change in the available speed over time, over a period of one week, between a document server station and a client station in a communication network; - Figure 3 shows a typical example of changes in the workload of a document server station over a period of time of a week, in a communication network; FIG. 4 represents a typical example of the evolution of requests for downloading documents received by a document server station during a period of time of one week, in a communication network; - Figure 5 is a block diagram showing the part of the document transfer device according to the invention, which is incorporated in a server station connected to the communication network; - Figure 6 is a block diagram showing the part of the document transfer device according to the invention, which is incorporated in a client station connected to a communication network; - Figure 7 shows an example of a table according to the invention in

  i15 which are stored statistical information of available flow in function

  tion of time between a document server station and the various stations

  clients making download requests, in a communication network

  munication; - Figure 8 shows an example of a table according to the invention in which are stored statistical information on the workload as a function of time of a document server station, in a communication network;

  FIG. 9 is a flow diagram illustrating the method for determining

  nation of at least one document transfer date according to the invention; Figure 10 is a flowchart detailing the step of determining transfer dates in the flowchart shown in Figure 9; FIG. 11 is a block diagram representing a computer capable of incorporating the components of the client part and / or of the server part,

  document transfer device according to the invention.

  With reference to Figure 1 we will describe an example of a network

  adapted to implement the invention.

  Network 1 actually comprises two subnets 2, 3. Each of the subnets comprises a plurality of computers and peripherals linked together through the network. For example, subnets 2 and 3 can be local area networks (LAN) based on known architectures such as Ethernet or Token Ring, or connected corporate networks

  between them via a telephone network.

  The subnet 2 thus comprises in this example three computers 20, 21 and 22 and a printer 23 connected to the subnet 2 via

computer 20.

  The second subnet 3 has three computers 30, 31 and 32

  and a printer 33 connected to the subnet 3 by the computer 30.

  These two subnets 2 and 3 are connected by means of computers 22 and 32, belonging respectively to the first subnet 2 and to the second subnet 3, each of these computers 22, 32 being connected to a modem 24, 34. These modems 34, 44 are themselves connected via a telephone communication network 4, and by way of nonlimiting example via a switch 5 which is located at the same access provider (in English service provider), common to the two networks 2, 3. This structure allows the two subnets 2, 3 to communicate, so that a user of the first subnet 2 can use the elements of the second subnet 3 as if they belonged

  physically at the first subnetwork 3, and vice versa.

  For example, a file stored on computer 21 of the first sub-

  network 2 can be printed on printer 30 connected to the second sub-

  network 3 via computer 30.

  Subnets 2 and 3 can also be integrated into a planetary communication network, such as the Internet, built on top of a communication protocol allowing computers connected to the

  communication network to exchange documents. For each of the sub-

  networks Internet access is achieved for example via the network

telephone communication 4.

  The computer documents that computers connected to network 1 can exchange are stored at the level of computer servers. In network 1, this server can be any computer

  among computers 20, 21, 22, 30, 31 or 32.

  In what follows it is assumed by way of example that the function of

  computer server is performed by computer 31 of network 3.

  Client stations likely to request transfer (or download) of documents whose access is managed by the station

  server 31, in this example are the other computers connected to the network.

  The server 31 hosts in a local memory - for example, in a hard disk - a plurality of electronic documents accessible via

  the network by client stations.

  As mentioned above in the description, the transfer time of an electronic document, between the server 31 and a client station such as for example, the computer 21 varies according to the capacity and the state of congestion of the

  network as well as the server workload.

  The congestion state of the network at a given instant can be evaluated by measuring the data transfer rate available at this instant, expressed in kilobits per second (kbps), between the server station and the station.

client considered.

  In general, the maximum bit rate usable for data transfer between a server and a client station in a network is conventionally designated by the term "bandwidth" (in English bandwidth) and

  expressed in kilobits per second (kbps).

  FIG. 2 gives an example of evolution of the instantaneous speed available as a function of time, between a document server and a given client station. As can be seen in the figure, the available flow is measured over a period of time of one week. In the graph in Figure 2, the ordinate axis represents the percentage of bandwidth used. At a given instant, the value of the available bit rate is consequently all the lower the fraction of the bandwidth already used for this purpose.

instant is high.

  The abscissa axis in the graph represents time,

  segmented into intervals representing the days of the week.

  It can be observed that the instantaneous speed available is lower in general during the working days of the week (in English working days) since the rate of bandwidth used is higher on average during these days. Conversely, the instantaneous flow available is higher during the weekend. The example in Figure 2, for example corresponds to a network of a company in which employees use their computer

  to download documents during their working days.

  The corresponding workload in the server is shown in Figure 3. This workload is a function of download requests sent to the server by network users. Load

  the server is therefore weaker during the weekend.

  In practice, the load on the server is determined from the measurement of the utilization rate of the central processing unit (CPU) of the server, this being able, for example, to be constituted by one or more microprocessors. FIG. 4 is a histogram representing the typical evolution of requests for downloading documents, originating from a plurality of client stations, received by a document server in a communication network. The observation time period is still one week,

  as shown on the x-axis.

  The ordinate axis corresponds to the number of download requests (designated by the term "appointment") received per day of the

week.

  Thus, it can be seen that the graphs shown in Figures 2, 3 and 4 are correlated. Indeed, an increase in download requests received by the server induces an increase in the workload of the central processing unit of the server, following the processing of these requests, and consequently an increase in traffic on the network, due to the transfer.

  number of data requested to the requesting stations.

  Thus, we observe that the day of Thursday is the subject of a peak of download requests (fig. 4) which leads to an increase on the same day of the workload in the server (fig. 3), and an increase on

  the bandwidth rate used (fig. 2).

  FIG. 5 is a functional diagram representing the part of the document transfer device according to the invention, which is incorporated in a server station (for example the computer 21) connected to the communication network.

communication 1.

  The "server" part of the document transfer device according to

  The invention comprises the units described below.

  A unit 301 for receiving a deferred transfer request. The function of this unit is to receive delayed transfer requests from client stations via network 1, and to extract the data contained therein. A deferred transfer request is identified in the server as being a deferred transfer request by the fact that the request contains information inserted on transmission by the client station which allows the server, upon receipt of the request, to decode this request. information and process the request

according to the invention.

  This information contained in the request is, in a preferred embodiment of the invention applied to the Internet, an additional field coded in the download request, the latter using for example the communication protocol known by the acronym HTTP (HyperText Transfer Protocol), or the one known by the acronym FTP (File

Transfer Protocol).

  The reception unit 301 then transmits the data contained in the transfer request to a unit 303 for obtaining the size of the data. The function of this unit is to extract information identifying the document to be transferred from the request, to deduce the place of storage in the server of this document, and to obtain its size (expressed for example in kilo- bits), by calculation or by reading this in the header of a file

containing this document.

  Thus, provision may be made to perform a test on the size of the requested document, so as to exit from the deferred transfer mode if the size of the

  document is determined to be below a predetermined threshold.

  The document identification information is, for example, a file name or a storage address such as for example a URL (Uniform Resource Locator), making it possible to identify the storage location of the

document in the server.

  The data contained in the request is then transmitted to a unit 305 for obtaining the customer identity. The function of the unit 305 is to extract client identification information from the transfer request

  to identify the client station at the origin of the request.

  This customer identification information is, according to a preferred embodiment of the invention, a logical address making it possible to identify the

  client station in the network, for example its Internet Protocol (IP) address.

  More particularly, according to an alternative embodiment, it is the logical address (IP address) identifying the subnetwork to which the client station belongs. Thus in the case of the network illustrated in FIG. 1, if the client station is station 21, it will be the logical address identifying the subnetwork

2.

  Still with reference to FIG. 5, the document transfer device according to the invention comprises a unit 307 for selecting transfer dates. The function of this unit is to determine at least one suitable future date for transferring the requested document according to a predetermined transfer efficiency criterion. In practice, this efficiency criterion of

  transfer consists in minimizing the document transfer time.

  To perform its task, the date selection unit 307 uses the services of three auxiliary units: - an available speed prediction unit 309, - a server workload prediction unit 316,

  - a unit 324 for searching for available dates.

  PREDICTION OF AVAILABLE FLOW BETWEEN THE SERVER AND THE CUSTOMER STATION

  The function 309 of available speed prediction has the function of making an estimate of the available speed between the server and the client station,

  for a predetermined period of time in the future.

  For this purpose, the unit 309 uses the services of three other units: a unit 311 for measuring available flow, - a unit 313 for calculating flow statistics,

  - a unit 315 for storing flow statistics.

  The unit 311 for measuring flow has the task of calculating the transfer rate used during the actual transfer of a given document between the server and the requesting client station. In accordance with the invention, this flow rate is calculated at regularly spaced times according to an interval of

  predefined time for the duration of the transfer.

  At each instant of calculation, the transfer rate which has

  was available during the time interval ending at the time of the calculation.

  Thus, if we designate by At the time interval between each measurement of the flow rate, the flow rate available during a given interval At is obtained by calculating the ratio between the quantity of data received by the client station during this interval of time and the value of this time interval Rate (Af) = Data received Ddbit (A (t)) = At According to a preferred embodiment of the invention, the rate available at an instant tn is the amount of data actually received over there

  client station between successive instants tn.1 and tn.

  In practice, the quantity of data actually received by the client station is obtained between the aforementioned times, by calculating the difference between the total amount of data received by the client station at time tn since the start of the transfer, and the total amount of data received by the client station at time t, .1 since the start of the transfer: Rate (! n) = Data_ received (tn) - Data _ received (tq) t ', -t1, _ According to a embodiment, the quantity of data actually received by the client station at a given time is obtained by accounting for acknowledgment messages (in English "acknowledgments messages") received in the server, originating from the client station. Thus, as an example, suppose that a document whose size is 1.8 Megabytes (million bytes, 1 byte = 8 bits) was completely transferred on June 14, 2000 between 11:35 am and 12:20 pm (duration 45 minutes). We also assume that the measurement time interval is At =

15 minutes.

  We will then measure the flow at times t1 = 1 1h50, t2 = 12h05, and t3 = 12h20. On the other hand, we note to = 1 1 h 35, the instant of the start of the transfer. If for example, at time th, the amount of data received by the client station is 0.45 Megabytes, at time t2 the amount of data received is 0.75 Megabytes, and at instant t3 the entire document has been received (1.8 Megabytes), then we will have Dgbit (t) = Data _ received (t) -Data_ received (to) (0.45 - 0.0) x 106 x 8 40.0 kbps Bit rate (tt) = 4 - to15x6 0 0 Bit rate (t) Data - received (t2) Received_data (tQ) (0.75 - 0.45) x 106 x8 26 kb Bit rate (t2) = 26.6 kbps t2 ti 15 x60 Data rate (t) Data_ received (t3) - Data_ received (t2) (1.08 - 0.75) x 1 06 x 8 293 kb Data rate (t3) = __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ 29.3 kbps t3 - t2 15 x 60 We can therefore say that the transfer speed available for the transfer of the document considered was on average 40 kbps (kilobits per second) between 11:35 a.m. and 11:50 a.m., 26.6 kbps on average between 11:50 a.m. and

  12.05 hrs, and 29.3 kbps on average between 12.05 hrs and 12.20 hrs.

  The flow measurement unit 311 transmits each measurement carried out

  to the unit 313 for calculating flow statistics.

  Unit 313 collects and organizes measurement data, and

  stores in the unit 315 for storing flow statistics.

  According to an exemplary embodiment of the invention illustrated in FIG. 7, the unit 315 for storing bit rate statistics is in the form of an association table in which data are associated with each other

  date, address data and measured flow data.

  The association table (315) shown in FIG. 7 is incorporated in a memory comprising several registers adapted to record the data obtained by the unit 311 for measuring flow. It includes a first register M1 containing the dates for which the statistics are available. A second register M2 contains the network address relating to the client station considered. A third register M3 contains the measured value of the bit rate corresponding to the associated date and address. As illustrated in FIG. 7, the register M2 contains, in accordance with a preferred embodiment of the invention, the address of the subnetwork to which the client station object of the document transfer belongs. In practice, this is the IP address of this subnet. So we can reduce the amount

  data to be stored and therefore reduce the size of the table (315) used.

  On the other hand, it is possible in this way to generalize the bit rate information available to a set of client stations connected to the same subnet. Of course, as a variant, the address stored in the register M2 can be the IP address of

  the client station considered itself.

  According to an embodiment characteristic, the dates stored in the register M1 correspond to instants spaced apart according to an interval of

  predefined time over a total period of time also predefined.

  In the preferred embodiment, this time interval is minutes and the overall period of statistics available is 7 days preceding the current day. Of course, it is possible to provide measurement time intervals and a period of time for the availability of these different measurements, depending on the precision of the estimation of the desired flow rate and of

  the importance of average traffic on the network considered.

  Thus, using the previous example of the 1.8 Megabyte document transferred to the client station on Wednesday June 14, 2000 between 11:35 am and 12:20 pm, as illustrated in Figure 7, the following dates are stored

  in the register M1: MER-14/06 / 00-11h50; MER-14/06 / 00-12h05; SEA-

  14/06 / 00-12h20. For each of these dates, the IP address of the subnet to which the client station concerned by the transfer of the file will be stored in the M2 register. In the previous example, this address is the same for the 3 aforementioned dates and is noted "ADR (SR2)" (address of subnet 2)

in table 315.

  Finally, the register M3 will contain for each of these dates the measured flow value, that is to say the values 40.0; 26.6; and 29.3

  (kbps), as shown in Figure 7.

  Returning to FIG. 5, the available bit rate prediction unit 309 uses the bit rate statistics stored, as described above, in the bit rate storage unit 313, to make an estimate of the bit rate available between the requesting client station (or the subnet to which said client station belongs) and the server, over a period

  predetermined time in the future.

  According to a preferred embodiment of the invention, this predetermined period of time relating to the estimation of the available bit rate in the future, is equal, in duration, to the period of availability in the past (for example one week) of the statistics. of debt. The start of the estimation period

  corresponds to the instant of the start of the flow estimation process.

  The estimation of the future throughput according to the invention is based on the hypothesis based on network observations, according to which the use of a document server varies very little from one week to another. Thus the foreseeable available flow for a day to come, at a given time, will be very little different (on average) from that observed on the same day (and at the same time) of the week

previous.

  Thus, the predicted value of the transfer rate available at a future date is considered to be equal to the value of the transfer rate calculated on an "equivalent date" within the preceding week. In the preferred embodiment, the concept of "equivalent date" consists of considering the same day, in the sense of its rank in the week considered

  Monday, Tuesday ..., Sunday; and the same time on this day.

  SERVER WORKLOAD PREDICTION

  Returning to FIG. 5, the unit 316 for predicting the workload of the server has the function of estimating the workload of the server during a predetermined period of time in the future. This workload is defined in relation to the activity of the server for downloading

of documents.

  For this purpose, the load prediction unit 316 uses the services of three other units: - a load measurement unit 318, - a load statistics calculation unit 320,

  a unit 322 for storing load statistics.

  The unit 318 measures the workload of the server at the same times and for a period of time identical to those defined for the unit 311 to measure the available speed between the server and a given client station,

  or, for example, every 15 minutes and for a period of 7 days.

  According to a preferred embodiment of the invention, the server load is determined on the basis of the measurement of the utilization rate of the central unit (CPU) of the server, which can be, for example, incorporated

  by one or more microprocessors.

  The load measurements thus obtained are supplied to the statistics calculation unit 320, the function of which is to collect and organize the measurement data, and store them in the statistics storage unit 322

dump.

  According to an exemplary embodiment of the invention illustrated in FIG. 8, the unit 322 for storing load statistics is in the form of an association table in which data are associated with each other.

  date and measured load data.

  The association table shown in FIG. 8 is incorporated into a memory comprising several registers adapted to record the data obtained by the load measurement unit 322. It includes a first register N1 containing the dates for which the statistics are available. A second register N2 contains the value of the workload

measured on the corresponding date.

  Thus, using the previous example, on Wednesday June 14, 2000, the instants spaced every 15 minutes between 11:30 am and 1:00 pm, will be stored in the register N1. In the register N2, the workload values measured at these times will be stored. In practice, the load values

  are expressed as a percentage of CPU used.

  Thus, by way of example, in the table represented in FIG. 8, on the date "MER-14/06 / 00-12h05" in the register N1, corresponds in the register

  N2 the workload value "45" (%).

  Returning to FIG. 5, the charge prediction unit 316 of

  server work uses stored load statistics, as described below

  above, in the load statistics storage unit 322, to estimate the server workload over a predetermined period of

time in the future.

  According to a preferred embodiment of the invention, this predetermined period of time relating to the estimation of the server workload in the future, is equal, in duration, to the period of availability in the past (for example a week) load statistics. The start of the estimation period corresponds to the moment when the process starts

load estimation.

  The estimation of the future server load, according to the invention, is based, as for the available speed, on the assumption based on network observations, according to which the workload of a document server varies little one week to another. Thus the workload of the server foreseeable for a day to come at a given time, will be very little different from that observed on the same day of the previous week, at the same time. Thus, the value of the workload predicted at a future date is considered to be equal to the value of the workload measured at an "equivalent date" within the preceding week. In the preferred embodiment, the concept of "equivalent date" consists, as for the prediction of the transfer rate, to consider the same day, in the sense of its rank in the week considered: Monday, Tuesday ..., Sunday; and the same time

in this day.

  Thanks to the services provided by the units 309 and 316, the date selection unit 307 determines at least one future date for transferring the document requested by the client station in question, so as to minimize the document transfer time. Thus, in accordance with the invention, future dates are selected according to the available throughput and the rate of use of the server, which have been predicted for these dates, respectively by

units 309 and 316.

  However, since the deferred document transfer service is offered to all client stations in the network, the date selection unit 307 uses the services of the available date search unit 324, so as to avoid possible, that the same future date is selected for a large number of client stations to perform a

deferred transfer.

  SEARCH FOR AVAILABLE FUTURE DATES TO MAKE THE TRANSFER

  The unit 324 for searching for available dates uses the services of three other units: a unit 325, known as an agenda, in which the download appointments already taken are stored; a calendar update unit 324 responsible for updating the unit 325 as a function of transfer dates chosen by client stations; a unit 333 for receiving selected dates, responsible for receiving, via network 1, from client stations, dates chosen for

  perform a delayed download.

* Indeed, if a date (expressed in day-time) selected as the possible date for the download, is already reserved by several client stations to carry out a delayed download, the performance of the server may be slowed down, following the increased workload on that date. Another case can arise which consists in that several stations of the same sub-network have made appointments on the same date or in the vicinity of this date. In this case, even if the server's predicted workload remains "reasonable", simultaneous downloading to the same subnet address can cause a spike in traffic on the access link to this subnet. This traffic peak can then limit the speed available to carry out each of the downloads taken in isolation, and by

  therefore increase the document transfer time.

  Thus, the unit 24 for searching for available dates, provides the unit 307 for selecting dates, the information necessary for it to be able to select dates also according to the availability of the server at

these dates.

  Returning to FIG. 5, the transfer device (server part) further comprises, according to a particular embodiment, a unit 329 called

  "calculating applicable discounts".

  The function of this unit is to classify the dates proposed by the date selection unit 307, according to a download cost criterion. This cost can be, for example, the financial cost of connecting to the server from a client station. In the case of the Internet, this cost may be linked to the local pricing applied by the network provider when the user connects to the Internet via his telephone line. This cost can be, alternatively or cumulatively, the price paid by the user to an Internet service provider allowing access to the document server. This cost may also be the purchase price of the document, payable by the user in order to download it, the document possibly being software supplied by a software publisher within the framework of trade.

electronic on the Internet.

  The rates offered by the network provider and / or by the service provider may be variable depending on the time of connection to the network, or depending on the time of connection to the server. So, for example, the service provider may offer lower rates at certain times of the day or on certain days of the week, so

  to smooth the server workload.

  In this hypothesis, the conditions of reduction of financial cost according to the dates of transfer of documents, are memorized

  in a memory 327, called "reduction scale".

  The memory 327 is consulted by the unit 329 for calculating the applicable reductions, to classify and / or make an additional selection on the transfer dates obtained from the unit 307 for selecting the dates,

  so as to minimize the financial cost of the transfer.

  Still in FIG. 5, the transfer device (server part) of

  document includes a unit 331 for transmitting selected dates.

  This unit (331) has the function of sending a message, for example an HTTP message, to the client station via the network 1, said message containing the dates finally selected for carrying out the transfer of the

  document requested by the client station.

  As will be explained below, in connection with FIG. 6, the client station, at the origin of the deferred transfer request, will process the message containing the dates selected by the server, and will respond to the server by referring to it. a message containing the transfer date finally chosen. Messages containing the dates chosen by the stations

  clients are processed in the server by the unit 333 for receiving the date chosen.

  As mentioned above, the selected date reception unit 333 supplies the selected dates received by it (i.e. the appointment dates) to the calendar update unit 335 so that the latter can update

agenda 325 with these dates.

  Finally, when a date chosen by a client station has arrived, as will be explained later in connection with FIG. 7, the client station considered sends the server a "classic" transfer request to carry out

  the actual transfer of the requested document.

  Conventionally, this transfer request is processed in the server by a transfer request reception unit 337. This extracts and provides identification unit 339 with the data identifying information

of the requested document.

  Finally, the unit 339 makes a copy of the identified document 341 and supplies the data to be transmitted to a conventional data transmission unit 343, which sends the copy of the requested document to the client station

considered, via the network (1).

  We will now describe, in relation to FIG. 6, the part of the document transfer device according to the invention, which is incorporated in

  a client station connected to the communication network.

  As an example, we consider that the client station considered

  is the station 21 of the network 1 represented in FIG. 1.

  The "client" part of the document transfer device according to

  the invention comprises the units described below.

  First, a unit 201 for issuing a deferred transfer request has the function of generating a deferred transfer request in accordance

with the invention.

  As mentioned above in connection with FIG. 5, this request contains information, such as an additional field in an HTTP type request, which allows the server to interpret this request as being

  a deferred transfer request.

  According to a particular embodiment characteristic, when the user, for example via a web browser, activates a command triggering the launching of a transfer request, a dialog box is displayed on a screen fitted to the client station, to give the choice the user to launch a transfer request of the classic type, with effect

  immediate, or else launch a deferred transfer request according to the invention.

  As a variant, provision can be made for the deferred transfer mode to be activated each time the user sends a (conventional) command to

  document transfer, for example using a keyboard.

  In the cases described above, a software component (program) according to the invention intercepts the conventional command for transferring

document before processing.

  Another variant consists in equipping the client station with software such as a "web browser" capable of

  generate a deferred download request for documents.

  Unit 201 sends, via network 1, the delayed transfer request

  to the server which processes it as explained above in conjunction with FIG. 5.

  The server sends back, by its unit 331 for sending dates, a message containing at least one transfer date selected by

  the server to perform the transfer.

  In the client station, the message containing the selected dates is received by a unit 203 for receiving selected dates. The unit 203 extracts from the message received the selected dates, and the

  transmits to a unit 205 of choice of dates.

  The function of this unit 205 is to allow the determination of a final date for effecting the transfer. This determination can

  operate in three distinct modes.

  According to a first mode, the possible dates are displayed on a screen with which the client station is equipped, the user then chooses according to

  personal convenience a transfer date among these dates.

  According to a second mode which can be complementary to the first, the unit 205 consults a memory called "agenda" in which are stored the dates of availability of the user and / or the future dates previously chosen by the user to carry out a transfer. of document. The unit 205 then determines a date among the possible dates according to the

  availability of the user according to the data stored in the calendar (207).

  According to a third mode, the unit 205 compares the dates selected by the server with the dates stored in the calendar 207, so as to choose a date (among the dates selected by the server) according to the availability of the client station . The availability of the client station is defined in relation to the download appointments previously taken with a server (the same or another) to perform a document download. In this mode, lastly, if several dates for which the service rendered is equivalent in terms of transfer efficiency, the user is asked to make a choice according to his

personal convenience.

  Finally, when a final date is chosen to carry out the

  transfer, this is transmitted to a unit 209 for transmitting the selected date.

  The unit 209 then sends a message containing the chosen date to the server via the network 1. The server receives this message via its chosen date reception unit 337 and processes it as described above in connection

with figure 5.

  Once the chosen date has been issued, a unit 211 called "calendar update" is responsible for updating calendar 207 with the new date chosen so as to prohibit or limit the choice of this same date for a

another transfer in the future.

  Still in FIG. 6, the client part of the transfer device according to the invention comprises a unit 213 called "alarm". This "alarm" 213 is "programmed" by unit 207 (calendar) when it has been updated by

the update unit 211.

  The alarm 213 is programmed by the agenda 207, to "wake up" a download process when the chosen date has arrived. Thus, on this date, a conventional transfer request is sent, by a unit 215

  transmission request transmission, to the server, via network 1.

  The server receives this request, as explained above, via its transfer request reception unit 337 and processes it

in a classic way.

  Finally, the server sends the corresponding data to the client station which receives it via a data reception unit 217. The unit 217 transmits the data received to a storage unit 219. The unit 219 stores this data, for example on a hard disk of the client station, then a display unit 221 is responsible for displaying on the screen a

  message to notify the user of the arrival of the requested document.

  We will now describe, in conjunction with the flowchart shown in Figure 9, a method of determining at least one date for performing a document transfer, in accordance with the invention. This method is implemented in the server part of the document transfer device

according to the invention.

  The method for determining at least one transfer date is implemented as soon as the server receives a deferred transfer request

  of document from a client station (step 901).

  As described above in relation to FIG. 5, the address of the client station sending the request is then determined (step 903), and

  identifies the requested document (step 905).

  Once the document has been identified, size S is determined (step 907)

  of this document (size expressed in kilobytes for example).

  A test is then carried out relating to the size of the requested document. To this end in the next step (909), the size (S) of the document is compared to a predefined threshold (SO). We could for example choose this equal threshold

at 500 kilobytes.

  If the size of the requested document is less than the predefined threshold, it is considered that, given its size, the document can be downloaded immediately without significantly penalizing the document transfer time. In this case, the transfer date chosen to operate the transfer of the document is the current date (step 919). The current date is for example the date of reception of the response of the user validating the proposal of the server to operate an immediate transfer. A response is then generated at the client station (step 915)

  containing a message offering an immediate download.

  The message is then sent, via the network, to the client station

(step 917).

  Returning to test step 909, if the size of the document is strictly greater than the threshold SO, then the deferred transfer will be carried out according to the invention. To this end, in step 911, one or more possible dates in the future are determined to operate the transfer of the document according to one or more predefined criteria relating to the efficiency of the transfer (transfer time,

financial cost of transfer).

  As described above in relation to FIG. 5, the possible transfer dates are selected (step 911) from consulting the storage units containing the load statistics (unit 322), the available throughput statistics (unit 315) , and the availability data of the

waiter (agenda 325).

  Once the possible dates for carrying out the transfer have been determined, the financial cost reductions that can be applied to these dates are calculated (step 913) by consulting the memory storage unit.

  reductions (scale of reductions 327).

  A response is then generated (step 915), intended for the client station concerned, containing the determined dates with the information also

  relating to the applicable reductions.

  Finally, we send this response to the client station, via the

network (step 917).

  We will now, in relation to the flow diagram represented in FIG. 10, detail the procedure for determining possible dates for carrying out the transfer (step 911, FIG. 9), according to a preferred embodiment.

of the invention.

  In this exemplary embodiment, the statistics concerning the speed available on the network (unit 315), the workload in the server (unit 322), and the dates of appointments already made (agenda 325), are

  available for a period of 7 days following the current day.

  As shown in FIG. 10, the date determination procedure begins with step 9110 in which, by consulting the flow statistics stored in the unit 315, the set D1 of dates is determined

  for which the flow is maximum.

  It will be recalled here that, according to the embodiment described and illustrated by the figures, a date consists of the date of the day considered in the month, associated with a given instant in this day (the instants being taken, by

example every quarter of an hour).

  In the next step (9111), the set D'1 of the dates is determined for which the available flow is close to the determined local maximums

in the previous step.

  The term "local maximum" means a maximum value of available flow predicted for a given time interval, for example, one hour. The term "close" is defined in relation to a difference measured between a local maximum and the flow value associated with another instant of the same day. For example, we could define that a flow rate value is close to a

  local maximum if their deviation is less than 10%.

  According to the same principle as for the available bit rate, in step 9112, the set D2 of the dates for which the server workload is minimum is determined by consulting the load statistics stored in the unit 322; and in the next step (9113) the set of

  dates for which the workload is close to local minimums.

  Then, in step 9114, the set D3 of the dates for which the server is most available is determined. For this purpose, we consult the agenda 325 and we determine the dates for which there are the least appointments made with client stations to operate a document transfer. Finally, in step 9115, the future dates are selected to operate the download, by calculating the mathematical intersection D between

  the previously determined sets: D'1, D'2, and D3.

  We then refer to the main procedure (Fig. 9) the result of this

  calculation, D, containing all the possible dates selected.

  Thus, according to this embodiment, the possible dates for operating the document transfer are those for which there is simultaneously a relatively high available speed (predicted), a relatively low server workload (predicted), and a server availability. , in terms of

appointment already made, high.

  These three conditions, combined together, minimize the

  document transfer time, if completed on these dates.

  Referring now to FIG. 11, there will be described a computer suitable for incorporating the components constituting the server part and / or the client part of the transfer device according to the present invention.

  which has been described above, in particular in relation to FIGS. 5 and 6.

  Of course, in an equivalent manner this computer comprises, consequently, means capable of implementing a method of transfer (server part and / or client part) of document according to the invention and described

  above, in particular in relation to FIGS. 7 to 9.

  In this embodiment, the means constituting the document transfer device according to the invention are essentially

software components or programs.

  Consequently, these software components comprise one or more sequences of instructions whose execution by said computer allows

  the implementation of the methods according to the invention.

  In FIG. 11, the computer 10 which can typically be a microcomputer or a workstation, conventionally comprises a central unit (CPU) 100, connected to a read only memory (ROM) 101 and to a

  random access memory (RAM) 102, as well as a data bus 112.

  The data bus 112 allows communication between the

  different sub-elements of computer 10, or the elements linked to it.

  However, the communication between the various sub-elements of the computer is not limited to the bus 112. In particular, the central unit 100 is capable of communicating instructions to any sub-element of the computer 10

  directly or through another sub-element of the computer 10.

  The computer 10 includes a communication interface 110 connected to a communication network such as the network 1 (represented in FIG. 1) such as the Internet network and capable of receiving documents, for example of the type using HTML language (HyperText Markup Language). This communication interface 110 comprises for example a modem of type known from

  the skilled person (in English "skilled person").

  The computer 10 also conventionally comprises a storage means 106 such as for example a hard disk. It can also include a floppy drive 107, a CD-ROM drive 108 and a

  format card reader called PC-CARD 109.

  A floppy disk 7, a compact disc (CD) 8, a card 9 of the PC-CARD type, intended to be read respectively by the floppy disk drive 107, the CD-ROM drive 108 and the card reader 109; as well as the hard disk 106, can be used for the storage of documents transferred according to the invention, as well as for the storage of the software code allowing the setting in

  work of the transfer method according to the invention.

  According to a preferred embodiment, the executable code of the program making it possible to implement the transfer method, is

stored in the hard drive 106.

  According to an alternative embodiment, the executable code of this

  program is stored in ROM 101.

  According to another alternative embodiment, the executable code of the program can be downloaded from the communication network 1 via

  the communication interface 110 to be stored on the hard disk 106.

  The communication interface 110 is for example a browser

network (in English web browser).

  When the program is run, the variables created and

  modified are stored in registers of RAM 102.

  The computer 3 furthermore comprises a screen 103 making it possible to serve as a graphical interface between the program according to the invention and the user, the latter being able to formulate requests using for example a

  pointing such as a mouse 105, or using a keyboard 104.

  The computer 10 furthermore comprises various peripherals, such as a printer 14 making it possible for example to print downloaded documents, or a fax machine 17. These peripherals are connected to the computer

via an entry / exit card 111.

  Of course, many modifications can be made to the embodiments of the invention described above without departing

of the scope of the invention.

Claims (28)

  1. Method for determining at least one date on which to carry out the transfer of an electronic document from a server station to a client station via a communication network, the method being implemented in said server station upon receipt by this of a request for transfer of a document sent by said client station, the method being characterized in that it comprises the following steps: generating (911) predicted values of transfer rate, between the server station and said client station, on a plurality of dates within a first predetermined period of time in the future; - determining (911) from at least said predicted transfer rate values, at least one date, within said first predetermined period of time, to which the document can be transferred according to a   predetermined criteria for transfer efficiency.   2. Method according to claim 1, characterized in that the step of generating (911) of said predicted values is preceded by the following step: - generating and storing first data (315) representative of the transfer rate available during previous document transfers, between the server station and at least one client station in the network, at a plurality of dates within a second predetermined period of time in the past; said transfer rate predicted values being generated (911)   from said first data.   3. Method according to claim 2, characterized in that it comprises, before the step of determining at least one date within said first predetermined period of time, the following steps: - generate and store seconds data (322) representative of the workload of the server station measured on the plurality of dates within said second predetermined period of time in the past; - generating (911), from said second data, predicted values of workload of the server station, at the plurality of dates within said first predetermined period of time said at least one date, within of the first predetermined period of time in the future, to which the document may be transferred, being determined based on said predicted throughput values of   transfer and said workload predicted values.   4. Method according to claim 1, 2 or 3, characterized in that it further comprises the following step: - send (915, 917) to said client station information   indicative of the said at least one specific date.   5. Method according to claim 4, characterized in that it further comprises the following step: - receiving from said client station, information indicative of a date chosen from said at least one determined date, said selected date   being the date on which the document will be transferred.   6. Method according to any one of the claims   previous, characterized in that each of said first data (315) includes a speed value (M3) associated with a network address (M2) and a date (M1), each speed value corresponding to a calculated transfer speed value on the associated date, during a document transfer between the   server station and a client station identified by the associated network address.   7. Method according to claim 6, characterized in that, during a document transfer, the transfer rate is calculated at regularly spaced times according to a predefined time interval during the duration of the transfer.   8. Method according to any one of claims 2 to 7,   characterized in that said first and second predetermined periods of time are equal in duration, and the predicted value of transfer rate at each date among the plurality of dates within the first period of time, is equal to the value of transfer debit calculated on a date equivalent to   inside the second period of time.   9. Method according to any one of claims 3 to 8,   characterized in that each of said second data (322) includes a workload value (N2) of the server station, associated with a date (N1), each load value corresponding to a load value measured at the associated date.   10. Method according to any one of claims 3 to 9,   characterized in that the predicted value of workload on each date among the plurality of dates within the first time period, is equal to the value of workload measured on an equivalent date within the second period of time.   11. Method according to any one of the claims   above, characterized in that said predetermined transfer efficiency criterion mainly consists in minimizing the transfer time of said document.   12. Method according to any one of claims   previous, characterized in that the step of determining (911) at least one date, in the first period of time, to which the document can be transferred according to a predetermined transfer efficiency criterion, takes into account a criterion minimizing the financial cost of downloading the document. 13. Method for obtaining at least one date on which to transfer an electronic document from a server station to a client station via a communication network, the method being implemented in said client station, the method being characterized in that that it comprises the following stages: - send to the server station a first request to transfer a document; - receive from the server station information indicative of at least a future date; selecting a date from said at least a future date; - receive the document from the server station on the selected date. 14. Method according to claim 13, characterized in that the step of selecting a date comprises the following sub-steps: - consulting a memory (207), in which are stored dates of availability of the client station and / or the user of the client station; - comparing the dates stored in the memory (207) with said at least some future date.   15. The method of claim 13 or 14, characterized in that it further comprises, between the step of selecting a date and the step of receiving said document, the following step: - activate an alarm (213 ) intended to trigger, on said selected date, the sending to the server station of a second transfer request of said document.   16. Method according to any one of claims 13 to 15,   characterized in that the step of selecting a date is followed by a step   transmission of the selected date to the server station.   17. Method for transferring an electronic document from a server station to a client station, said stations being connected by a communication network, characterized in that it comprises: - implemented in said server station, the steps d '' a method for determining at least one date on which to carry out the transfer   an electronic document according to any one of claims 1 to 12;   - implemented in said client station, the steps of a method for obtaining at least one date on which to transfer a document   electronic device according to any one of claims 13 to 16.   18. Device for determining at least one date on which to carry out the transfer of an electronic document from a server station to a client station via a communication network, the device being characterized in that it comprises: - means (309) for generating predicted transfer rate values, between the server station and said client station, at a plurality of dates within a first predetermined period of time in the future; - means (307, 327, 329) for determining from at least said predicted transfer rate values, at least one date, within said first predetermined period of time, at which the document   may be transferred according to a predetermined criterion of transfer efficiency.   19. Device according to claim 18, characterized in that it comprises: - means (311, 313) for generating and storing first data (315) representative of the transfer rate available during the transfer of documents, between the server station and at least one client station in the network, at a plurality of dates within a second predetermined period of time in the past; said predicted transfer rate values being generated at   from said first data.   20. Device according to claim 19, characterized in that it comprises: - means (318, 320) for generating and storing second data (322) representative of the workload of the server station measured on the plurality of dates within the second predetermined time period; - means (316) for generating, from said second data, predicted values of workload of the server station, at the plurality of dates within the first predetermined period of time in the future; said at least one date, within the first predetermined period of time in the future to which the document can be transferred, being determined as a function of said predicted throughput values of   transfer and said workload predicted values.   21. Device according to claim 19 or 20, characterized in that it comprises means for implementing a method for determining at least one date on which to effect the transfer of a document   electronic device according to any one of claims 4 to 16.   22. Device for obtaining at least one date on which to transfer an electronic document from a server station to a client station via a communication network, said device being characterized in that it comprises: - means (201) to send a first document transfer request to the server station; - means (203) for receiving information indicative of at least one future date from the server station; - means (205) for selecting a date from said at least one future date; - means (217) for receiving said server from the server station   document, on the selected date.   23. Device according to claim 22, characterized in that it comprises: - a memory (207), in which are stored dates of availability of the client station and / or of the user of the client station; - means (205) for comparing the dates stored in the   memory (207) with said at least one future date.   24. Device according to claim 22 or 23, characterized in that it comprises: - alarm means (213) intended to trigger, on said selected date, the sending to the server station of a request for transfer of said document; - means (207) for activating said alarm means (213) at the selected date.   25. Device for transferring an electronic document from a server station to a client station, said stations being connected by a communication network, characterized in that it comprises: - a device for determining at least one date at which to transfer an electronic document, according to any one of claims 18 to 21; and   - a device for obtaining at least one date to which to transfer   an electronic document according to any one of claims 22 to 24.   26. Server station connected to a communication network, characterized in that it includes a device for determining at least one date on which to carry out the transfer of an electronic document, according to   any one of claims 18 to 21.   27. Client station connected to a communication network, characterized in that it comprises a device for obtaining at least one date on which to transfer an electronic document, according to any one from claims 22 to 24.   28. Communication network comprising at least one client station according to claim 27, and at least one server station according to claim 26.