Abstract:
An adaptable replica server system comprising a primary replica being associated with a primary storage for storing information and a primary processing means, and a secondary replica being associated with a secondary storage and a secondary processing means for creating confirmation data upon receiving input data from the primary replica, wherein the replica server system is designed to be configurable so as to work as an asynchronous server replica system and/or as a synchronous server replica system depending on an instruction.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to replica server systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    Failsafe operation of information technology systems is of fundamental importance for most modern society activities. Due to this there are many precautionary systems that are made to handle situations of failure. 
         [0003]    Such systems could comprise safeguarding of information via memory backup systems as well as safeguarding of complete system functionality. The latter could comprise completely mirrored or redundant systems, where all actions are executed in primary and secondary system components (computer, processor, server, etc). 
         [0004]    There are essentially two categories of replication, synchronous and asynchronous replication: 
         [0005]    In a synchronous replica system a customer does not get any confirmation for his transaction until it has reached both the primary site and the disaster recovery site. This implies that the latency for the transaction is increased at least by the round trip between primary and disaster recovery site. 
         [0006]    In an asynchronous replica system the customer gets a confirmation as soon as the primary has received it, replication to the disaster recovery site is best effort as soon as possible. This implies that in case of a disaster occurring at the primary site, there is a risk that some transactions confirmed to customers are actually not present at the disaster recovery site. An example of such a system is described in US 2006/0020635. 
         [0007]    In existing replica server system it is currently typically a basic IT architecture decision if one wants to use asynchronous or synchronous replication. For example in the case of an electronic exchange it is neither the electronic exchange nor its participants that can choose which policy to use. 
         [0008]    In the financial field, e.g. electronic exchange systems for stocks, bonds, derivates, etc, failsafe high-speed in-memory servers are used. These systems are also referred to as replica server systems. Similar to the above disclosed system, a replica server system comprises a primary replica and a secondary replica, both being identical and in the same state. Should the primary replica fail, the secondary replica will take over immediately. Of course, the system may contain several secondary replicas to improve safety. Upon failure of the primary replica, one of the secondary replicas will then become a new primary replica, while the others remain as secondary replicas. 
         [0009]    The resent trend of program/algorithmic trading in the financial field, and the evolution of competitive electronic exchanges, e.g. the same security being trading at more than one exchange, has created a need for minimum latency. The current expectation level is to have sub millisecond response time on order transactions, this is more or less impossible due to speed of light limitations, if one likes to have synchronous replication and a reasonable distance between the Primary and disaster recover site. 
         [0010]    Moreover, in some applications, e.g. Government Bond trading, the value of an individual transaction is so high that synchronous replication is a must. No one is prepared to accept the risk of losing one such transaction in case of fail-over to the disaster recovery site. 
         [0011]    Thus one problem with present replica server systems and other similar systems is the architecture of the system. Either they are synchronous or asynchronous as described above, thus the systems are not flexible. 
         [0012]    Another problem with known replica server systems is that they do not differ between different messages. 
         [0013]    There is thus a need for an adaptable replica server system and especially a replica server system that considers different types of messages while operating large numbers of parallel transactions. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    In accordance with the invention a method and system of improving replica server system performance is provided. 
         [0015]    It is an object of the invention to provide an improved replica server system. 
         [0016]    It is a further object of the invention to provide a replica server system that manages different type of input data differently, depending on the content of the input data. 
         [0017]    Thus according to a first aspect of the invention, the above and other objects are achieved by providing an adaptable replica server system comprising a primary replica being associated with a primary storage for storing information and a primary processing means, and a secondary replica being associated with a secondary storage and a secondary processing means for creating confirmation data upon receiving input data from the primary replica, wherein the replica server system is designed to be configurable so at to work as an asynchronous server replica system and/or as a synchronous server replica system depending on an instruction. 
         [0018]    Thus in one embodiment the replica server system may comprise a user interface whereby a user can set an instruction parameter so that the replica server system either works as a synchronous replica server system or as an asynchronous replica server system. 
         [0019]    In another embodiment the adaptable replica server system may be configured to treat different input data differently. Thus depending on a content value in the input data the replica server system may either act as an asynchronous server replica system or as a synchronous server replica system. Thus the replica server system checks each input data and decides on how the checked input data should be managed. 
         [0020]    In a further embodiment the adaptable replica server system, may work as an asynchronous server replica system and/or as a synchronous server replica system depending on input data comprising an attribute. Thus a user can, for each input data sent to the adaptable replica server system, decide how a specific input data should be treated by setting a value to the attribute as will be described below. 
         [0021]    In an embodiment of the method according to the present invention, input data received by a primary replica is transferred to a secondary replica. 
         [0022]    Output data from the primary replica can be sent as soon as the primary replica have stored and processed the input data or it can be sent once the primary replica has received confirmation data from the secondary replica. Thus, when the secondary replica has received the input data and acknowledges it by returning confirmation data to the primary replica. When the output data is sent from the primary replica may depend on an attribute that the input data comprises. Thus input data comprising an attribute can be sent to the replica server system. Preferably the attribute has the value set to safe or to fast. If the value is set to fast the output data is sent from the primary replica as soon as the primary replica have stored and processed the input data. If the value is set to safe the output data is sent from the primary replica after the primary replica have received confirmation data from the secondary replica. 
         [0023]    Notably, there is with this method possible for customers or participants of the server replica system to decide on how they want the system to work, thus an adoptable server replica system is realized that can be tailored to each user and participant specific need, even adapted to each specific data input. 
         [0024]    Thus, according to a second aspect of the invention the above and other objects is solved by providing a method for improving a replica server system comprising a primary replica being associated with a primary storage for storing information and a primary processing means, and a secondary replica being associated with a secondary storage and a secondary processing means for creating confirmation data upon receiving input data from the primary replica, comprising the steps of: 
         [0025]    receiving input data comprising at least one attribute, 
         [0026]    transferring input data from said primary replica to said secondary replica upon receiving same, 
         [0027]    processing said input data in said primary processing means after storing said input data, thus creating original output data 
         [0028]    based on the attribute, sending said original output data either after said original output data is created by said primary processing means or upon receiving said confirmation data from said secondary replica. 
         [0029]    With the above method a more flexible solution can be achieved since the architecture does not need to fixed and decided on in the early stages of the development or implementation process. Instead the configuration can be done when setting up the system, or it can continuously be monitored and input data can be managed either asynchronously or synchronously. Thus by managing input data by its content for example by the attribute, it is possible to adapt the replica server system to specific needs and situations. 
         [0030]    Preferably the attribute comprises at least one of the following values: Safe and/or Fast. However other values may also be chosen, or the input data can be classified automatically to belong to either safe or fast based on a content value in the input data. For example if the input data comprises an order to an electronic exchange and the order has a high volume (large number of instruments) and/or the instruments has a high price. In such a case the replica server system according to the invention can automatically classify the input data to belong to safe, whereas input data with little volume or low priced instruments may be classified as fast. This classification can either be done at the first replica server in an electronic exchange. However the classification may also be done at a participant&#39;s broker work station or at a server at the participant&#39;s location, such as a gateway or any other network device that is located outside an electronic exchange. Thus, input data received from such a broker work station or electronic device will already comprise an attribute having a value when it arrives at the first server replica. 
         [0031]    Thus, the server replica system may further comprise an identifier for identifying and classifying such input data, the input data further comprises a content value, the identifier being configured to identifying the content value in the input data and based on the content value, assigning the attribute in the input data a value. 
         [0032]    According to a third aspect of the invention the above and other objects is solved by providing a replica server system comprising a primary replica having a primary input, a primary output, a primary storage and a primary processor associated with it which is connected to a secondary replica having a secondary input, a secondary output, a secondary storage and a secondary processor associated with it, said primary replica being configured to transfer received input data comprising at least one attribute value to said secondary replica, store said input data on said primary storage, process said input data on said primary processor to create original output data and based on the attribute value sending said original output data either as soon as original output data is created in said primary processing means or send out said original output data through said primary output after receiving confirmation data from said secondary replica that said input data has been received, and said secondary replica being configured to generate said confirmation data upon receiving said input data on said secondary input. 
         [0033]    According to a fourth aspect of the invention the above and other objects is solved by providing a replica server system comprising: primary replica means; secondary replica means; means for communicating internally between said primary replica means and said secondary replica means and externally between said primary replica means and external sources, said means for communicating being configured to transfer input data comprising at least one attribute received by said primary replica means to said secondary replica means; means for storing said input data in said primary replica means; means for processing said input data in said primary replica means, thus creating original output data; means for generating confirmation data in said secondary replica means upon receiving said input data and transferring said confirmation data to said primary replica means via said means for communicating; and means for outputting said original output data either as soon as original output data is created in said primary processing means or upon receiving said confirmation data from said secondary replica, based on the attribute value. 
         [0034]    According to a fifth aspect of the invention the above and other objects is solved by providing a computer terminal for entering and transmitting server input data to a server system, the input data comprising at least one attribute value, the computer terminal comprising setting means for setting the attribute value defining the server input data to be managed either as safe server input data or as fast server input data, upon arrival at the server system. 
         [0035]    The computer terminal may be a broker work station from which orders are sent as input data into an electronic exchange comprising the replica server system. However the computer terminal may be any type of terminal such as a mobile terminal, i.e. a mobile phone, or other hand held device. 
         [0036]    The server input data sent from the computer terminal may further comprise a content value, the setting means further being configured to set the attribute value based on the content value in a similar way to what is described above for the system. 
         [0037]    The content value may belong to a group of content values, the group comprising: Instrument type, Volume, Value, and id. The content value may be chosen to be one or more of the above mentioned values. 
         [0038]    Instrument type may for example be stocks, bonds, swaps, options, or any type of commodity such as oil, energy and so forth. Volume can be any type of volume applicable to the above mentioned instrument types. Thus for stocks it is preferably the number of stocks whereas for oil it may be barrels and for energy it may be watts, joule etc. Value can be either the price for one instrument of the value for the whole order thus volume*value. Id may for example be the ID of the participant sending the order. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]      FIG. 1  is a schematic drawing of a first embodiment replica server system shown in an operating environment for the invention; 
           [0040]      FIG. 2A  shows on a schematic event line an event cycle for a state of the art replica server system; 
           [0041]      FIG. 2B  shows on a schematic event line an event cycle for a replica server system according to the invention; and 
           [0042]      FIG. 3  is a schematic drawing of a second embodiment replica server system shown in an operating environment for the invention. 
           [0043]      FIG. 4  shows on a schematic event line an event cycle for the present invention. 
           [0044]      FIG. 5  shows on a schematic event line an event cycle for the present invention 
           [0045]      FIG. 6  illustrates a structure of input data. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]      FIG. 1  generally depicts a replica server system  100  according to the invention. The replica server system  100  comprises a primary replica  101  having inter alia a primary storage  102  for storing information, a primary identifier  120  for identifying input data, a user interface  122  for configuring the system, and a primary processor  103  for processing data. 
         [0047]    The primary storage  102  is preferably a buffer storage of known kind, but could also include a hard disc memory, a writable CD or DVD disc or any other known persistent memory capacity for data. Unlike prior art replica systems, however, the replica server system  100  will normally not flush after each event to write data on disc (although this may still be included—but that would reduce most of the positive effects of the invention since flushing normally is the most capacity-limiting step in the process). Normal flushing when the buffer is full can of course take place (and will do so) to obtain a register of performed transactions. 
         [0048]    The primary processor  103  could be any state of the art central processor or combination of processors used in computers, servers, etc. 
         [0049]    Further, the replica server system  100  comprises a first secondary replica  104  and a second secondary replica  107 . Basically, the replica server system  100  could comprise any number of secondary replicas suitable for the applications of the system. The first secondary replica  104  includes inter alia a first secondary storage  105 , a first secondary identifier  120  and a first secondary processor  106 , and the second secondary replica  107  includes inter alia a second secondary storage  105  a second secondary identifier (not shown) and a second secondary processor  106 , all of which could have the same type of components used for the primary replica  101 . In a hardware sense, the primary replica  101  and two secondary replicas  104 ,  107  can be (and preferably are) identical. 
         [0050]    The primary replica  101  and the secondary replicas  104 ,  107  communicate internally via a communication unit  110  and communication link  111 . The communication unit  110  also provides communication with external sources  113  via a communication network  112 . The communication network  112  could use different communications channels for different external sources  113 , e.g. via Ethernet LAN, telephone, satellite, etc. The external sources  113  could comprise terminals, computers, electronic exchanges or any other device(s) from which data to be processed by the replica server system  100  may originate. The external sources  113  also receive output data from the replica server system  100 . 
         [0051]    In use input data received from the external sources  113  is routed to the primary replica  101  via the communication unit  110  and communication link  111 . The input data is then sent from the primary replica  101  to the secondary replicas  104 ,  107  via the communication unit  110  and communication link  111 . Preferably, the input data is sent immediately from the primary replica  101  upon receiving it. 
         [0052]    Similar to the communication network  112 , the communication link  111  can comprise several different kinds of wired or wireless components, mainly depending on the location of the secondary replicas  104 ,  107 . For instance, the first secondary replica  104  may be placed in the vicinity of the primary replica  101  and use a broadband connection, whereas the second secondary replica  107  may be placed far away and linked to the primary replica  101  via satellite. 
         [0053]    When the secondary replicas  104 ,  107  receive the input data, they will generate confirmation data (acknowledgement) that they have received the input data and send the confirmation data to the primary replica  101 . Preferably, acknowledgment is done immediately upon receiving the input data. 
         [0054]    Meanwhile, the input data are saved onto the primary storage  102  and processed in the primary processor  103  in the primary replica  101 . Hereby, original output data is created. Depending on the attribute value of the input data the output data is either sent when the data has been processed in the primary processor. If this is the case the replica server system acts as an asynchronous replica server system. However it the attribute value is set to safe mode the out put data is sent when the primary replica  101  receives the confirmation data from the secondary replica  104 . Thus in this case the replica server system acts as a synchronous replica server system. In one embodiment a process configured to check the value input data is preferably present in the primary and secondary replica. Thus the identifier  120  may either be configured to check the attribute vale in the input data in so that the system manages the input data based on the attribute value which in this embodiment has been set outside the replica server system. In another embodiment the identifier  120  may both assign the attribute value based on the content value and thereafter manage the input data based on what attribute value that has been assigned to the input data. 
         [0055]    Independently of how the system is configured, the original output data is sent to the external sources  113  via the communication unit  110 . It is sufficient for the safety of the replica server system  100  to allow the primary replica  101  to wait for the first acknowledgement from one of the secondary replicas  104 ,  107 . This can essentially reduce latency; cf. the above example with the first secondary replica  104  located nearby and connected via a fast broadband communication link (e.g. Ethernet LAN 100MB) and the second secondary replica  107  located far away and/or connected via a slow communication link (satellite). Notably, this will reduce latency for individual events or transactions, i.e. time span from input till output, not the number of transactions operable per time unit. 
         [0056]    Once the primary replica  101  has sent the input data, it is ready to receive new input data (next input data). In line with what has already been described, once the next input data is received by the primary replica  101 , it sends the next input data to the secondary replicas  104 ,  107  and then proceeds by storing and processing this next input data. 
         [0057]    Preferably the external sources  113  are computer terminals configured to sent input data. The external sources preferably comprise setting means  121  in order to set an attribute value to input data that is to be sent. Setting means  121  can either be a keyboard that makes it possible for a user of the external source to manually set the attribute value. It can also be a module in a computer that is configured to automatically set the attribute value based on e.g. content value of the input data. 
         [0058]      FIG. 2A , shows the basic operational steps of a state of the art asynchronous replica server system. 
         [0059]    Input data arrives as indicated with line  200  to a primary replica (represented by event line  201 ). The input data is stored on disc, a procedure that takes a certain disc write time, represented by designation W 1 . Following this, the input data is transferred to a secondary replica (represented by event line  202 ). This process takes time, depending on where the secondary is situated and is represented as network latency time N 1 . Again, the input data is written to disc, accumulating a second disc write time, W 2 , to the total time. Once the input data is also written on the secondary replica, acknowledgement (confirmation) is returned to the primary replica. A second network latency, N 2 , adds to the total time for the procedure. Finally, the primary replica may process the input data, which requires a process time P 1  and output the result as indicated with designation number  203 . 
         [0060]    It should be noted that event lines  201 ,  202  are not representative as linear real-time indicators. Write time W 1 , W 2  is normally extensively longer than process time P 1 , for instance.  FIGS. 2A and 2B  are intended to illustrate the effects and benefits of the invention and not a real-time schedule of the server replica systems operations. 
         [0061]    All in all, writing time W 1 , network latency N 1 , writing time W 2 , network latency N 2  and process time P 1  amounts to an accumulated time T 1 =W 1 +N 1 +W 2 +N 2 +P 1  required to perform one operation (transaction). 
         [0062]    Also in  FIG. 2A , a next input data is indicated in dotted lines and with designation number  204 . The same process is repeated with the next input data—all indicated with dotted lines—which ends with output data as indicated with numeral  205 . 
         [0063]    In  FIG. 2B  one aspect of the timesavings obtained according to the state of the art described in US 2006/0020635, incorporated by reference. Input data is indicated at  210  and reaches the primary replica (indicated by event line  211 ). The input data is immediately transferred to the secondary replica (indicated by event line  212 ), which takes a certain time depending on location of the secondary replica. Here, it is assumed that the placement is the same as in  FIG. 2A . It thus requires network latency N 1  to transfer the information. As soon as the secondary replica receives the input data, acknowledgement (confirmation data) is sent back to the primary replica, causing time delay of network latency N 2 . The processed data can be output at  213 , i.e. as soon as the input data is processed and confirmation is received from the secondary replica. 
         [0064]    Turning now to  FIG. 3 , a second preferred embodiment of a replica server system  300  is schematically described. 
         [0065]    The replica server system  300  comprises a primary replica  301  and a secondary replica  302 . The primary replica  301  includes a primary communication module  303 , a primary storage  304 , a primary identifier  320  and a primary processor  305 . The secondary replica  302  likewise includes a secondary communication module  306 , a secondary storage  307 , a secondary identifier  330  and a secondary processor  308 . As with the first embodiment in  FIG. 1 , any known component enabling communication, storing and processing could be utilised. Likewise, the different components could be separate units or integrated into one or more units. Other functionalities can also be included within the replicas  301 ,  302 . 
         [0066]    The primary communication module  303  and the secondary communication module  306  are linked (by wire or wireless) to enable communication between the primary replica  301  and secondary replica  302 . The primary communication module  303  can also communicate with external sources (not shown) via communication link  309  (wire or wireless). In case of failure of the primary replica  301 , the secondary replica  302  will become a new primary replica. In such case a router  310  will enable the secondary replica  302  to communicate with the external sources. The function of the router  310  could also be implemented (hardware or software) in the primary communication module  303  and the secondary communication module  306 . 
         [0067]    When input data arrives from an external source via communication link  309 , the primary replica  301  will transfer the input data to the secondary replica  302  and then proceed by storing the input data in the primary storage  304  and process the input data in primary processor  305 . Once acknowledgement or confirmation data is received from the secondary replica  302 , the processed data can be output back to the external sources. When a next input data is received and transferred to the secondary replica  302  or when information data from the primary replica  301  indicate that the input data has been processed successfully, the secondary replica can store and process the input data. 
         [0068]    In  FIG. 4  and  FIG. 5  the aspects of the advantages according to the present invention is described in relation to prior art systems. The options that the output data can be sent is illustrated by lines  216  and  217 . The time lag between these lines is the time difference in response time for safe input data and fast input data. The response for fast input data is line  217 . 
         [0069]    When input data arrives at the primary replica some processing time may be needed in order to check what attribute the order comprises. 
         [0070]    In  FIG. 6  an example of input data  600  is illustrated. The input data may comprise an attribute value  601  and a content value  602 . 
         [0071]    Usually the content value is automatically assigned when the input data is created at the external device  113 . For example in a trading system when a trader creates an order the trading application creates an order comprising a volume and a price. 
         [0072]    All functionalities described above are applicable for the embodiment in  FIG. 1 . Combinations between the shown embodiments are also possible. For instance, the embodiment in  FIG. 3  can include the user interface  122  or more than one secondary replica and the replicas in  FIG. 1  can all include communication means for the internal communication between replicas. 
         [0073]    Other embodiments are viable with simple and straightforward modifications of the embodiments disclosed above. These are also viewed as falling within the scope of the invention, as disclosed by the accompanying claims.