Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR TRANSMITTING A CHAIN OF
MESSAGES FOR DATABASE
Field of the Invention
The present invention concerns a process and system of database updating, and
in
particular during the transmission of a chain of messages.
Related Art
In a system comprising a management centre and a plurality of subscribers over
a
wide territory, the sending by telephone or hertz route of updating
information of the
database of these subscribers is known. These messages are addressed, either
to
all subscribers, or to one subscriber in particular, that is to say that it
contains a
subscriber module address.
These messages are for the administration of the system and are themselves
superposed to the useful data such as video, audio or data. One understands
that
the place used by these messages is limited. Another limitation applies to the
length
of the message which is limited by the fact that the useful data cannot be
interrupted
but for a short moment. One understands that, in the example of an audio/video
transmission, the emission channel cannot be interrupted but for a short
moment so
that no visual impact will be perceptible.
This is why, for transmission of a large amount of data, it has been necessary
to
divide them in a large number of messages.
These messages are sent in sequence on the network, in a logic order, that is
to say
one after the other, separated by a short interval, for example one second.
As certain systems of this type do not use return towards the managing centre,
as for
example a modem, it is difficult for the managing centre to know if the sent
data has
arrived correctly. In this way, it is obliged to repeat these messages
periodically so as
to statistically ensure that each message has arrived at destination.
A subscriber module includes schematically a numerical, audio, video or data
receiver, to see a combination of these three types, a decoder able to
separate the
management messages, these latter being directed towards a security module
comprising the subscriber database. This security module can be directly
installed in
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the subscriber module or, for security and cost reasons, it can be as a
detachable
module such as an intelligent card or microchip card.
The messages arriving at the security module are processed by the control-data
reader. It is possible that the messages do not arrive in the emission order
because
of interferences in the transmission or simply as the subscriber's unit was
not
engaged at the moment of the sending of previous messages. It is necessary to
specify that prior to each processing, each message is first decrypted and
controlled
for its authenticity. A message which does not satisfy the control criteria is
rejected.
In this hypothesis, the security module will receive for example the sign
message 3
before the sign messages 1 and 2. The execution of the sign message 3 without
the
prerequisite execution of two previous messages can lead to blocking of the
database or to a certain error.
A first solution consists in memorising all messages constituting a chain and,
when it
is complete, to proceed to its processing. This solution has the drawback to
establish
the length of the maximum chain according to the memory available.
The memory capacity of detachable intelligent cards is limited, which obliges
the
card to process each message at each arrival.
Summary of the Invention
The problem that the present invention proposes to solve, is to suppress on
the
subscriber's database the disastrous effects due to the execution of messages
in an
order different to that initially foreseen.
This aim is fully reached by a transmission process of a chain of subscriber's
database management messages, a process consisting to associate a conditional
block which determines if the message is to be processed without reference to
all or
part of others element of the chain or the conditions bound to the previous
processing of all or part of other elements of the chain.
In fact, due to this new conditional block included in each message elements
of a
chain, it is possible to determine if this message can be processed separately
or
must satisfy the conditions of processing of the messages considered to be
received
first. It is obvious that this test allows also to determine if the message in
evaluation
has already been processed.
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To reach this aim, the security module disposes of a memory organized under
the
form of table indicating, for each chain which are part of the messages of
this chain
already having been made object of a processing. After processing of all the
elements of the chain, the table of this chain is maintained in order to avoid
that the
returning of the same chain restarts its execution. It can be deleted on
request of the
management centre or after a predefined time.
The conditional block contained in the message does not contain only a simple
indication binding the processing of the message in progress to condition of
having
carried out the previous message, but also covers the more complex functions,
such
as conditions on each element of the message chain. For example, it is
possible to
submit the processing of element 4 of the chain on the condition that both
elements
1 or 2 are processed and that element 3 is categorically processed. We will
thus
have the function:
F(4) = (1 or 2) and 3.
We take the example of the arrival to the security module of the message
element of
family 5, this message being element 4 of this family. The first operation
will be to
determine if its processing is submitted to other conditions. If this is not
the case, it
can be processed immediately. It should be noted that to chain messages does
not
mean that the processing must be made in the index order of the chain. One can
imagine the case where one loads a significant software, and for this reason,
one
divides it to transmit it in a chain of messages. Each of these messages
contains a
charging address and the corresponding data. This is why an element of the
chain
can be processed in a indifferent order. On the other hand, the last element
of the
chain starting this new software will contain a condition stating that all the
elements
of the chain must have been carried out in order that this one can be carried
out for
its part. When this condition has been satisfied, the table correspondent to
this family
indicates that all messages have been carried out.
According to a variant of the invention, the conditional block is divided in
two parts,
the one called "operation" to describe the type of logic function and the
other called
"interested element" to describe on which other elements the operation must
apply.
The size of the part "interested element" corresponds to the size used in the
table
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stored in the database designating the state of processing the elements of the
chain. In this way, the logic comparison is greatly facilitated.
According to other embodiments, the conditional block refers not to all the
other
elements of the chain, but to some only. It would be for example possible
referring to
three previous elements and not to all the elements. This allows to reduce the
length
of the conditional block and takes into account the fact that an interference
rarely
exceeds the time of three messages. According to another example, one could
define a chain structure where only the last element contains a conditional
block.
This structure allows, unlike the solutions of the prior art, to reject only a
minimum of
message. In fact, when a message is missed in a chain, all the following
messages
were rejected until the new passage of the missing message. The execution of a
chain was in this way dependent upon the continuous receiving of elements of
the
chain, each element missing having as a consequence to reject all the index
messages higher than missing message.
According to an embodiment of the invention, the subscriber module, besides
sending the messages to the security module, includes a memory to memorise
them
as soon as they arrive.
Therefore, it is possible that the absence of a message containing a condition
on a
preceding message leads to reject all the following messages. When this
attended
message arrives, it is of course processed authorising the processing of other
messages. It is possible on the other hand that a great deal of time elapses
before
these are present in the transmission with the risk that some are rejected,
for
example due to the bad quality of the connection between the managing centre
and
the subscriber module.
To minimize the number of repeated messages necessary for the chain is finally
carried out in its entirety, the security module can accede to memory situated
in the
subscriber module because it contains all the messages in their arrival order.
Thus,
as soon as the arrival of the missing message and its processing has been
accomplished, the security module asks the reading of the memory to process
all the
messages which have been rejected because of the condition on the missing
message.
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An important aspect of the invention lies in presenting each message to the
security
module together with the storage in memory in the subscriber module. This
principle
can include exceptions when some messages are not destined to the security
module but only to the module of the subscriber. Thus, even if some messages
are
rejected by the security module as the conditions are not fulfilled, this
system knows
that this message is contained in the memory of the subscriber module and can,
when the condition is fulfilled, accede to memory to carry out these messages
instead of awaiting a next passage of following messages.
In an embodiment, the memory of the subscriber module is organised as a stack
with
entry in series, each new entry causing the displacement of previous entry.
The reading by the security module can be realised in different ways. It can
ask the
transmission of an exact address of the memory. Nevertheless, an important
aspect
of the security in this kind of application lies in the confidentiality of the
organisation
of data. For this reason, instead asking the transmission of a specific
address, the
security module asks the subscriber module to submit all or part of messages
contained in its memory. A loading of the security module remains to sort out
between the messages already carried out and the messages to carry out.
Brief Description of the Drawings
The invention will be better understood based on the following detailed
description
which refers to annexed drawings which are given by way of a non limitative
example, wherein:
Figure 1 represents a message such as that sent in the systems of prior art;
Figure 2 represents a message such as that sent according to the invention;
Figure 3 represents an example of updating the temporary memory of the
subscriber module.
Detailed Description of the Preferred Embodiments
In Figure 1 the different blocks of a message which take part in the function
of
chaining are represented schematically. We find a first heading block HD,
which
describes the kind of message, and contains the information that this message
is
part of a chain. To form the chain, a second family block FM indicates to
which family
this message belongs. In fact, it is possible that several chains are
transmitted
simultaneously and in this case the identification of the family is necessary.
Now that
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the family is defined, the subsequent block FI is used to identify each
element of the
family and its place in the chain. So, with these two data, each element of
the family
can be placed again end to end with the other elements of the same family if
necessary. It is known to indicate in one or the other of control blocks FI or
FM the
maximum number of the element of the family. This function can equally be
obtained
by a particular marking of last element of the family.
In the example of figure 2, the message of Figure 1, starting the two blocks
FM and
Fl, one sees adjoining a supplementary block CD which determines a condition
to
carry out this message. According to a first embodiment of the invention, this
block is
constituted by a bit which indicates if the previous message should or should
not be
executed. If this condition is requested, the interpreter in charge of
operations on the
database, will verify if the previous message has been executed properly and
will
execute this new message.
In another embodiment, this conditional block CD is constituted by a field
realised
with groups, a group for each element of the chain. Each group contains a
condition
on an element of the chain and can have several meanings, for example the
condition "must have been executed", "can be executed" or "must not be
executed".
The latter condition generally corresponds to the first.
We take the example of a chain of 6 elements, the element 3 should forcedly be
carried out before element 5. In this case, one can specify in message 3 that
it
should not be carried out if message 5 has been done. This condition can lead
to a
locking if one does not specify the inverted condition in message 5. In this
case,
message 5 will contain the condition "must be executed", on message 3 in order
that
if message 5 arrived before 3, it will be not processed.
In Figure 3, an implementation of the memory M of the subscriber module and
the
connection with the security module are represented. The incoming flux is
firstly
filtered by a module SEL, which has the scope to separate the managing
messages
of other data. These messages are then transmitted to the selection module SW
which has the scope to send them to different modules that is to say the
security
module SM, to the processing centre CTR of the subscriber module STB and to
memory M of the subscriber module. The placing in memory of these messages
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causes the increasing of the number of incoming messages so that no message
will
be lost, the oldest message being then eliminated from the memory. In the same
way, these messages are transmitted to the security module, represented here
as an
intelligent card SM. This card SM contains a first memory managing module GM
and
a control interpreter INT for managing the controls of the database BD. This
memory
manager GM can dialogue with the processing centre CTR by the connection I/O
and.by this means, to influence the connections in the selection module SW.
The
dotted line represented in Figure 3 represents the subscriber module STB. All
the
managing messages addressed to the security module SM are directed by the
selector SW to the security module, in particular to the management of memory
GM,
then are transmitted to the control interpreter if the carrying out conditions
are
fulfilled. The memory manager GM updates the table of messages carried out to
make the necessary comparisons at the moment of the arrival of a new message.
The connection with the intelligent card SM is of in/out type and in this way
information and controls can be sent to destination of the subscriber module,
connection represented by the line I/O. As explained previously, the memory M
is
physically in the subscriber unit STB. This is why the card SM can, by the
intermediate of the line I/O, ask the availability of a memory section so as
to be able
to store the messages of a chain. In our example, the maximum number of
elements
in a chain does not exceed 16. So, at the arrival of the first element of the
chain, the
card SM, by the line I/O, requests the reservation of at least 16 memory
places. If,
during the transmission of this first chain, another chain is announced, the
card will
ask the reservation of 16 new places in order to assure the storage of a
maximum
number of the chain according to the receiving conditions.
In order to read the data contained in the memory M, for example the position
M3,
the card SM can order, through the selector SW, the address multiplexer AMUX
to
return the content of this memory position. In order to forward these data
towards the
card, a data multiplexer DMUX has the function to read the memory position
required
and to transfer it towards the card. These different transfers are directed by
the
selector SW.
When the carrying out of the chain has been interrupted by the lack of a
interference
on a message for example, the other messages continue to be stored in the
memory
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of the subscriber module. When the missing message is retransmitted by the
managing centre, it is executed properly and the memory manager GM recalls all
the
other messages of the chain acceding the memory of the subscriber module. In
this
case, the entry of the intelligent card SM is not made any longer on the
arrival of
messages but on the contents of the memory M. This access to memory M can be
made in direct access specifying a memory address, or by sequential access
reading
the messages in their arrival order.
In an embodiment, the memory M is organized as a memory buffer of a fixed
length
according to the availability of the free memory of the subscriber module.
This
memory includes an entry number increased on each message introduced in the
memory, and an exit number increased on each reading by the memory manager
GM.
The dialogue possibility between the card SM and the subscriber module STB, in
particular the centre CTR, authorises more complex functions. One of problems
frequently met at the moment of the exchange of one or the other of elements
of the
system, both the card or the subscriber module, is to assure the compatibility
of
functions with the material of previous generations. For this, it is
interesting to allow
dialogue between the different elements in order to establish the functions
available
in each of them; this is the scope of the line I/O which allows to send
instructions of
the card to the subscriber module. These instructions can, for example, ask
the
subscriber module to communicate its audio, video or data functions, the
generation
of the module or the software version. To answer to this request, the module
STB
disposes of means to compose a managing message and to transmit it, in the
memory M for further reading by the card, or directly to card, such as
represented in
Figure 3.
According to another embodiment of the invention, the module STB disposes of a
connection by modem with the managing centre. In this case, the announcement
of
resources can be made by the module STB to the managing centre through the
modem, on request of the security module SM.
As indicated in Figure 3, the module STB receives in the same way the managing
messages coming from the managing centre. The messages arriving to the
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processing centre CTR can contain a configuration request instruction. The
response
can be made by the modem or be transmitted to card SM. Some of these managing
messages are only destined to the module STB and the processing centre CTR,
responsible to the management of the module STB, will not transmit them to the
security module SM or to memory M.
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