CA2205883A1

CA2205883A1 - System and method for providing a managing system with information and a telecommunications system comprising such

Info

Publication number: CA2205883A1
Application number: CA002205883A
Authority: CA
Inventors: Johan Fantenberg
Original assignee: Individual
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1994-11-23
Filing date: 1995-11-22
Publication date: 1996-05-30
Also published as: NO972343D0; US6061685A; FI972175A; SE514798C2; CN1173259A; AU709996B2; SE9404054L; MX9703729A; NO972343L; WO1996016502A1; JPH10509290A; EP0793883A1; AU3997395A; SE9404054D0; FI972175A0

Abstract

The present invention relates to a system and a method respectively for providing a managing system (1) which manages a number of managed systems (2), with desired and up-dated information. At least one information storing means (3) is arranged which is provided with the original information which is relevant to the managed system(s) (2), which information storing means (3) is up-graded. The managing system (1) comprises means for fetching information from one of said information storing means (3) and the fetched information is held in information holding means comprising a cache (cache 4) arranged in the managing system (1).

Description

CA 0220~883 l997-0~-22 2 PcTlsE95Jol388 Title:
~Y~-l'~M AND M~l~O~ FOR PROVIDING A MANAGING SYSTEM WITH
INFORMATION AND A TELECOMMUNICATIONS SYSTEM COMPRISING SUCH.

FIELD OF THE INVENTION
The present invention relates to a ~yx~elll for providing a managing system which manages a number of managed ~ys~e~s with information. The invention also relates to a managing ~ysLc...
which is provided with information. The invention further relates to a method for providing a managing system managing a number of managed systems with information. Still further the invention relates to a telecommunications system comprising a number of managing systems each managing a number of managed systems in which the managing systems are provided with information.

Generally the amount of information relating to most managed xy~ is very high and complex to handle in an optimum way both because of the amount and because of the difficulty in getting access to the information that is really accurate, i.e.
information that is correct for the purpose, up-to-date and for example comprises the particular version or revision etc. that is actually ne~ . Thus in systems known today, the provision of the particular piece of information that is n~ is a difficult issue both because of the amount of information and because the information is not time-invariant, i.e. it is up-dated, changed etc.
Mostly, therefore, various tools are needed to enable the provision of information and support the user interaction with various managed systems.

STATE OF THE ART
In a number of systems which are known today managed systems comprise so called network elements which comprise various CA 0220~883 1997-0~-22 WO96tl6S02 PCT/SE9S101388 services and/or resources wherein in the network elements are comprised in a telecommunications network. The network comprises a considerable amount of various types of equipment but also a high number of various services may be comprised. Furthermore 5 equipment of one and the same type may be provided in a number t of different versions and revisions. Thus the different services and resources which are provided in the network element may be very complex for a user to handle, monitor and control. The information as such may comprise substantially all kinds of lO information that is needed by the user who interacts with the managed system, particularly it may describe usage, limitations, procedures, error-print-outs and so on.

The managing system, in the known embodiment referred to as 15 operations system, which here is used to monitor and control the equipment and the services provided by the network elements must know what information is related to a given piece of equipment or to a service. The operations system must also be informed on possible changes to the equipment and the services. This requires 20 that new information is made available to the operations systems.
This is both complicated and complex and it gets more difficult the higher the number of equipment and services existing. In order to facilitate the user interaction with the network elements it is known from the known system to provide graphical 25 tools for the user interface. However, even if the user interface is explanatory and the user interaction is facilitated, it is also important that the information is correct and up-to-date.

This puts requirements on a correlation of the information with 30 the ro~c~pt described by the information. A further complicating factor is that the operations system sometimes exist in a multi-lingual environment.

In order to provide an up-to-date information the information is 35 in the known system manually transferred to the operation systems. This gets very complex since it is necessary to maintain knowledge of which operations systems are used for managing a CA 0220~883 1997-0~-22 WO96/16S02 PCTIS~95101388 particular set of equipment and/or services. Furthermore, when new equipment or new services are introduced in the network elements, it may be necessary to introduce new information to the operations systems which is time consuming in a complex environment. The more complex the environment, the more time it takes. During the time spent on introducing this new information to the operations ~y~el~-s, the operations systems still work with the old piece of information relating to the nonr~ned e~uipment or the con~-~ned services which in turn may lead to improper actions being taken by the operator.

SUM~RY OF THE INVENTION
It is an object of the present invention to provide a system for providing a managing system with accurate, correct and up-to-date information in a reliable way and in a way which is not demanding for a user. Particularly it is an object of the invention to provide a system and a method for providing a managing system with an up-dated and correct view of the documentation and information on facilities such as e~uipment, services etc. that exist in a ~,_ ~n; cations system or a communication network in which the managed system or systems are arranged.

Another object of the invention is to provide a system and a method for facilitating monitoring and controlling of managed systems which are managed by the managing system. It is also an object to provide a managing system with information in order to facilitate user interaction with system managed by the managing ~yx~c.... Particularly it is an object of the present invention to provide a ~y~ ~e-ll and a method respectively through which it is not necessary to introduce new information to a managing system when systems managed by said managing system are provided with new information, up-graded etc. i.e. to provide for the managing ~ys~e~l not having to be up-graded. Particularly it is an object of the present invention to provide a system and a method respectively which fulfils the above mentioned requirements also when the amount of information, in particularly relating to various versions, revisions etc of equipments and services and CA 0220~883 1997-0~-22 so on provided by managed system, is high.

Still a further ob;ect is to correlate the information with information relating to the concept described by the information.
Yet another object is to provide a system and a method through which can be avoided the necessity of maint~; n; ng knowledge of which managing system manages a given managed ~y~e"- related to e.g. a given set of equipment or services etc.

In a particular embodiment it is an object of the invention to provide a system and a method for providing an operation system, managing a number of network elements in an efficient, correct and up-dated ~nn~r, with the information relating to the network elements managed by the operation system without having to up-grade the operations system itself when the services orequipments of the network elements are changed, up-dated, having been removed, added etc.

Moreover it is an object of the present inven~ion to provide for the provision of a managing system, in a particular case an operations system, with the correct and up-to-date information which is related to a given piece of information such as services, equipment etc.

It is also an object of the present invention to provide a telecommunications system comprising a number of managing systems which manage a number of managed systems wherein the managed systems are provided with accurate, correct and up-to-date information without having to up-grade the manaying systems when new information is introduced or when the information relating to services, equipments etc. are changed in one way or another.

These as well as other objects are achieved through a system and a method respectively which comprises at least one in~ormation storing means which is provided with original in~ormation documentation relevant to the managed systems managed by the managing system wherein said information storing means are up-CA 0220~883 1997-0~-22 WO 96/16S02 PCT/SEg5/01388 graded and wherein the managing system comprises means for fet~-h~n~ information from one of the information storing means and wherein the managing system further comprises a cache for holding the information that has been fetched from the information storing means.

Particularly a managing system is provided with on-line ~o~ tation which e.g. is stored in information storing means e.g. of a managed system. The information storing means is upgraded.

Through a telecommunications system the objects are achieved through the provision of information storing means which are up-graded when information is added, removed or changed in one way or another wherein each managing system comprises fetching means for fetching information from the information storing means and wherein the managing syx~ also comprises information holding means comprising a cache for holding the information that has been fetched from the information storing means.
It is an advantage of the invention that the managing system always has an up-to-date and correct view of the documentation of and information about facilities such as equipments, services etc. related to the managed systems. It is also an advantage that through the invention a system or particularly a telecommunications ~y~el~ is provided wherein the user interaction with the managed systems is facilitated. A further advantage is that the information that is nee~e~ does not have to be manually transferred to the managing systems and that no time is lost for introducing new information into the managing systems themselves, i.e. to up-grade them which prevents the user or the operator in a communication system etc. from taking improper actions.

It is also an advantage of the invention that the user knows that the documentation or the information that he is provided with is the correct documentation or information with respect to version, CA 0220~883 1997-0~-22 revision etc.

Still another advantage of the invention is that, since the managing systems do not have to be up-graded, the need for coordination of the overall system is considerably reduced.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention will in the following be further described in a non-limiting way under reference to the ~ nying drawings, in which:

Fig l illustrates a managing system being provided with information, ~5 Fig 2 illustrates one example of a managing system managing three managed systems and Fig 3 schematicallyillustratesatelecommunicationsmanaging network comprising a number of managing systems.
DETAILED DESCRIPTION OF THE INVENTION
In Fig l is schematically illustrated a managing system l which fetches information from a managed system 2 which is managed thereby. The managing system l comprises in the shown embodiment a number a management stations MNS 6. In the embodiment illustrated in this figure, management stations 6 are illustrated as being comprised by the managing system l but they may likewise be illustrated as not forming part of the managing system l. The managing ~y~e--l l as such can be a stand-alone system but it can also form a distributed system. The managing system l further comprises as an information holding means 4 a cache or an information cache for holding information which has been fetched from an information storing means 3 which will be further explained below. The cache 4 is managed by a cache manager 5. The cache 4 may further be shared in a LAN/WAN (Local Area Network/Wide Area Network) environment according to one embodiment although it is not necessary; a number of other CA 0220~883 1997-0~-22 WO 96/16S02 PCrlSE95~1388 alternatives naturally also being possible. A managing system generally comprises means in the form of hardware and software which is used for monitoring and controlling a number of managed systems, in the shown schematical embodiment however but one managed system 2. This is however so merely for illustrative purposes. The monitoring and controlling is sometimes generally exclusively carried out by software without any human intervention but in other cases human intervention is re~uired.
The user is then assisted by use of interactive software and documentation and the managing system provides the necessary functions.

The managed system 2 here comprises a logical database or an information database which holds the original or basic information. The logical database can be of many different kinds, e.g. a relational database, an ob~ect database or it may comprise a file system. A number of other alternatives are also possible.
The kind of media and the formate is not of importance for the present invention. Information is introduced in the logical database during an up-grading process. The information is "delvired" together with the software/hardware being described by the information. The logical database DB 3 as such may either be arranged in the means providing telecommunication services ~ etc. or it may be implemented in a distributed environment (see Fig. 2). The computer hosting the logical database DB can be used exclusively by one telecommunications system but it can also be shared by a number of telecommunications systems. The information of the logical database 3 can exist in a number of different versions and/or revisions and also for example be provided in a number of different languages. The managed system 2 comprises both hardware and software and it provides services or functions e.g. in a telecommunications network.

In the following the provision of the managing system 1 with information will be described in relation to Fig. 1; it is however generally relevant also to Figs. 2 and 3.

CA 0220~883 1997-0~-22 When a management association is to be established (or when a managed system 2 is activated) the managing system l checks if the information contained in the cache 4 is relevant, i.e. if it is correct and up-to-date. This may according to an advantageous embodiment be carried out in such a way that the information of the cache 4 is compared to information of the information storing means DB 3. If the information in the cache 4 is the same as the information in the information storing means 3 or the logical database DB of a managed system 2, then the information of the cache 4 is the wanted information and the information in the cache 4 is used. If on the other hand the information in the cache 4 is not the same as the information in the information storing means DB 3, then the information needs to be fetched from the information storing means 3. This can be done in different ways.

According to a first embodiment, the information is always fetched from the managed system 2. Advantageously the fetching process does not block other running processes. Then the managing ~y~ may send and receive management operations and notifications in the meantime when other processes, which might be blocked by the fetching process, are not r11nning.

According to a further embodiment the information is fetched from the managed ~y~L~ 2 when needed, i.e. when some information is re~uested and is not found in the cache 4 then it is fetched from the information storing means 3 (DB).

According to still another embodiment the information may be preinstalled in the cache 4 which reduces heavy first time lo~ings of the cache 4.

The manner in which the desired information is fetched can be done according to needs and ~ys~- , depending on which characteristics that are wanted etc.

The fet~hing operation can be carried out by use of a file CA 0220~883 1997-0~-22 WO96/16502 PCTISE9510138~

transfer protocol or through a distributed filed system or in any other ~ullvellient way.

After the information has been fetched it is installed in the ~ 5 cache 4. Then it can be accessed by a user or the tools supporting a user. The information in the cache 4 is maint~ine~
by the cache manager 5. The information storing means 3 (DB) comprise master information which as referred to above e.g. may be stored as files. Of course it can also be stored in number of other ways which are known per se since the storing media and formate is not important for the present invention as referred to above.

In another advantageous embodiment the managing system l may, when a management association is to be established, select where the original information or the information is to be fetched from. The information can be fetched from the actual managed system 2 (as illustrated in Fig. l) but it can also be fetched from some other information storing means or second information storing means 3" (Fig. 2) providing the information. In such an embodiment the information is duplicated within a network. This may e.g. be done in order to reduce the costs of access or to increase the robustness e.g. through allowing duplication. Thus also other information storing means, under reference to Fig. 2 referred to as second information storing means, may be up-graded parallelly with the information storing means 3;3' and it is the up-grading process which is responsible for the distribution of the information within the network or within the system.

Thus according to one embodiment a cache manager 5 may fetch the information from the managed system if necessary and from S~on~A~y sources 3" if the managed system l can not be accessed or if it is better in one way or another to fetch it from another or a secondary source, e.g. if it is cost reducing.
Advantageously the cache manager 5 as a rule checks in the cache 4 to see if it necessary to fetch any information and the cache CA 0220~883 1997-0~-22 4 may be preloaded, built up in parallel during the management session or built up as n~ as referred to above.

In Fig 1 a c ln~cation path between the managing system 1 and the managed system 2 is illustrated. CorresponA;ng communications are not illustrated in Figs. 2 and 3 for reasons of clarity.

In Fig. 2 one embodiment is Cch~ - tically illustrated wherein in a managing ~y~el.ll manages three managed systems 2a, 2b, 2c. The managing system 1 comprises a number of management stations MNS
6, a cache manager 5 and a cache 4 as described in the foregoing.
The information storing means (DB) 3' is implemented in a distributed environment and is shared by a number of managed ~yx~- ~ 2a, 2b, 2c in which each is illustrated a computer providing services or similar. The ~yx~elllalso comprises a second information storing means 3". The information in the information storing means 3' is duplicated and the up-grading process is up-grading both the information storing means 3' and the second information storing means 3". The managing system 1 selects if the information is to be fetched from the information storing means 3' (DB) or from t~e second information storing means 3" as already discussed above.

Fig. 3 illustrates an embodiment comprising a number of managing ~ysLe~s la, lb, lc, ld each managing a number of managed systems 2a, 2b, 2c; 3b, 3c, 3d; 2e; 2f and of which some managed systems comprise an information storing means (logical database) in the actual managed system 2a, 2b, 2c, 2d whereas for other managed ~ys~e~s 2e, 2f the actual information storing means 3' is implemented in a distributed environment as discussed above in relation to Fig 2. Management stations 6 are both comprised by the managing systems but also arranged "independently" 6'.

In one particular embodiment which also is illustrated by Fig 3 even if this Fig not exclusively describes this embodiment, the managing ~y~e...s comprise so called operations sy~e.~s and the managed ~y~e,--s comprise so called network elements and a so CA 0220~883 1997-0~-22 WO 96116S02 P~ 55lol388 ~ll~ tel~- ln; cations management network TMN provides management functions and offers communications as well between different operations systems as between operations ~y~ems and other parts of a tele~_ ~nications network. The network elements may comprise swit~hi ng ~y~ ~el~s~ exch~ges EXC, transmission systems etc. The invention can also be implemented in a tele _ ~n; c~tions management network TMN, as defined in CCITT
Recommendations M.3010 in which it can be said to be formed of a separate network which interfaces a tel~c ln;cations network at a number of different points for s~n~;ng/receiving information to and/or from it and for controlling its operations.
Particularly parts of the telecommunications network may be used by the TMN for the provision of its cor~-~n;cations. Fig. 3, as referred to above, in one aspect illustrates the application of the invention to the telef 7n; cation managing network TMN
concept.

A tel~ unications management network may e.g. at the lowest level relate to a ~onne~tion between an operations ~y~elll and a network element, but it may also relate to e.g. a whole network of operations ~y~ellls t controlling a large tele~o~l7n;cations network or anything therebetween. An operator interface denoted Q3 has been st~n~Ardized for a telecommunications system providing the connection between managing and managed systems.
In the recommendations relating to the GSM St~n~rd (Global System for Mobile Communications) subscriber administration is defined in the GSM Technical Specifications TS 12.02. According thereto the Q3 operator interface is specified for the provision of the subscriber ~; n; ~tration functionality. The Q3 interface defines both the object oriented information model of so called network elements and the communication protocol between the so called operations systems and the networks elements. In the CCITT
Re~ommendation No M.3010 a network element function block is defined as a functional block c: lnicating with the telecommunications management network TMN (for the purpose of being monitored and/or controlled). The network element function block provides the tel~c~ ~n;cations and support functions which _ _ _ _ _ _ _ _ _ _ _ .

CA 0220~883 1997-0~-22 are required by the teleccmmunications network that is managed.
It comprises the telecommunications functions which are the subject of management. The functions as such are not part of the TMN but they are represented to the TMN by the network element function block. The part of the network element function block that provides this representation in support of the TMN is part of the TMN itself whereas the telecommunications functions are outside the telec~ ~nications management network.
Furthermore an operations systems function block is defined as processing the information that is related to the telecommunications management for the purpose of monitoring/coordinating and/or controlling telecommunication functions including management functions.

This however merely relates to one embodiment, or one aspect of, the present invention.

In still other embodiments the principle of the invention applies to managing systems being managed by other managing systems on the same or on a higher logical level and the same principle applies for providing this higher level (or superior) managing systems with information.

Still further the principle of the invention applies to a managed system managing a hierarchically seen lower managed system or a subordinate system. Consequently the invention can be varied in a number of ways and it shall not be limited to the shown embodiments but merely by the scope of the claims.

Claims

1. System for providing a managing system (1; 1a, 1b, 1c, 1d) in a communications network, wherein said managing system manages a number of managed systems (2; 2a0, 2b0, 2c; 2a, 2b, 2c, 2d, 2e, 2f), with information which is up-to-date, c h a r a c t e r i z e d i n, that the system comprises at least one information storing means (DB, 3; 3', 3"; 3a, 3b, 3c, 3d, 3') which is provided with original information relevant to the managed system(s), that the information storing means (DB, 3; 3', 3"; 3a, 3b, 3c, 3d, 3') are upgraded and in that the managing system (1; 1a, 1b, 1c, 1d) comprises means for fetching information from one of said information storing means (DB; 3; 3', 3", 3a, 3b, 3c, 3d, 3') and means (cache, 4; 4a, 4b, 4c, 4d) comprising a cache for holding the information fetched from an information storing means (DB, 3; 3', 3", 3a, 3b, 3c, 3d, 3').

2. System according to claim 1, c h a r a c t e r i z e d i n, that each information storing means is a logical database (DB).

3. System according to claim 2, c h a r a c t e r i z e d i n, that the logical database comprises a relational database, an object database or a file system.

4. System according to claim 2 or 3, c h a r a c t e r i z e d i n, that each managed system comprises information storing means in form of a logical database (DB; 3; 3a, 3b, 3c, 3d).

5. System according to claim 2 or 3, c h a r a c t e r i z e d i n, that one logical database (DB; 3', 3") is common for a number of managed systems.

6. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the basic or the original documentation or information of each managed system is stored in at least one logical database (DB; 3; 3a, 3b, 3c, 3d).

7. Arrangement according to claim 6, c h a r a c t e r i z e d i n , that the original and upgraded information further is stored in a number of second storing means (3") e.g. each comprising a logical database copy and comprising the information relevant to at least one managed system.

8. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the upgraded information is duplicated and stored in a number of second storing means (3") and in that the managing system selects where to fetch the information from.

9. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managing system (1; 1a, 1b, 1c, 1d) comprises a cache manager (5; 5a, 5b, 5c, 5d) for managing the cache (4; 4a, 4b, 4c, 4d).

10. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managed system (1; 1a, 1b, 1c, 1d) comprises a number of management stations (MNS; 6; 6') comprising (a) user interface(s).

11. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the information storing means (DB; 3; 3', 3", 3a, 3b, 3c, 3d, 3') comprise(s) information which is provided in different versions, different revisions etc.

12. System according to claim 11, c h a r a c t e r i z e d i n , that the information is provided in a number of different languages.

13. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managing system comprises information access means (5;
5a, 5b, 5c, 5d) for checking if the information is valid.

14. System according to claim 13, c h a r a c t e r i z e d i n , that the information access means compares the information comprised in the information holding means with the information stored in the storing means (DB), and if the information in the information holding means (cache: 4; 4a, 4b, 4c, 4d) is the same as the information in the information storing means, the information in the information holding means is used and if the information in the information holding means and in the information storing means is not the same, the information in the information storing means (DB; 3; 3', 3"; 3a, 3b, 3c, 3d, 3') is fetched.

15. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that information is always fetched from an information holding means and/or from an information storing means when a managed system is activated.

16. System according to anyone of claims 1-14, c h a r a c t e r i z e d i n , that the information holding means, i.e. the cache (cache; 4; 4a, 4b, 4c, 4d) is preloaded.

17. System according to anyone of claims 1-14, c h a r a c t e r i z e d i n , that information is fetched from an information storing means (DB; 3; 3', 3''; 3a, 3b, 3c, 3') when needed.

18. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the fetching means comprises a file transfer protocol.

19. System according to anyone of claims 1-18, c h a r a c t e r i z e d i n , that the fetching means comprises a distributed file system or any other distribution mechanism.

20. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managing system controls and/or monitors a number of managed systems.

21. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managing system is a telecommunications operation and support system.

22. Arrangement according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managed system(s) is/are a network element.

23. Arrangement according to claim 22, c h a r a c t e r i z e d i n , that the managed systems comprise e.g. transmission systems, switching systems, signalling terminals etc.

24. System according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that the managing system is a stand-alone system.

25. Arrangement according to anyone of claims 1-24, c h a r a c t e r i z e d i n , that the managing system is a distributed system.

26. Arrangement according to anyone of the preceding claims, c h a r a c t e r i z e d i n , that a managed system forms a managing system for a number of secondary managed systems on a lower hierarchical level.

27. A managing system (1; 1a, 1b, 1c, 1d) for managing a number of managed systems (2; 2a0, 2b0, 2c0; 2a, 2b, 2c, 2d, 2e, 2f), c h a r a c t e r i z e d i n , that is is provided with on-line documentation which is stored in an information storing means (DB; 3; 3', 3"; 3a, 3b, 3c, 3d, 3') connected to or comprised by a managed system and in that the information storing means is upgraded.

28. Managing system according to claim 28, c h a r a c t e r i z e d i n , that the managing system (1; 1a, 1b, 1c, 1d) comprises an information holding means such as a cache (cache; 4; 4a, 4b, 4c, 4d) for holding information which is fetched by fetching means from the information storing means.

29. Telecommunications system comprising a number of managing systems each managing a number of managed systems and a number of user interfaces wherein each managing system comprises means for fetching the desired version, revision etc. of up-dated or upgraded information from information storing means comprising the information data relevant to one or more managed systems, wherein the managing systems furthermore comprise means comprising a cache for holding the information fetched from the information storing means, wherein the managing system uses the information stored in the information holding means of the managing system if said information is valid and otherwise fetches information from an information storing means.

30. Method for providing a managing system in a telecommunications network with up-to-date information of a desired kind wherein at least a number of managed systems are managed by the managing system, c h a r a c t e r i z e d i n , that information storing means comprised by or connected to a managed system is provided with basic or original documentation, at least one information storing means is upgraded by an upgrading process, the managing system fetches information from at least one information storing means either when needed, or always or in advance, the information is held in an information holding means comprising a cache of the managing system, information holding managing means checks if the information in the information holding means is valid and if yes, information of the information holding means is used and if no, information is fetched from the information storing means.

31. Method according to claim 30, c h a r a c t e r i z e d i n , that the cache is managed by a cache manager which compares the information held in the cache with information stored in an information storing means, e.g. a data base, and if the information is the same in the cache and in the information storing means, the information of the cache is used and if the information in the cache and in the database is not the same, the cache manager provides for fetching of information from the database.