Abstract:
A computer system includes a server that is connected to a database. The server receives incoming messages from one or mere of client devices and stores the incoming messages in a flat file. The incoming messages include instructions for updating the database. The server updates the database by performing update operations according to the received instructions, and compares a commit interval duration to a predetermined threshold. Based on results of the comparison, the server selectively issues a database commit command to make all database updates performed since a last database commit operation a permanent part of the database.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to electronic trading systems for trading stocks, bonds, futures, options and other financial instruments as well as betting and e-gaming, and in particular to methods, computer readable mediums and computer program products for such systems. 
   During the last decade, almost all the world&#39;s exchanges and marketplaces have introduced electronic trading systems. These systems either replace the traditional trading floors or are used as complements to them. Today a large number of exchanges throughout the world utilize electronic trading to trade stocks, bonds, futures, options and other financial instruments. These electronic exchanges generally include three basic components, namely server computers (host), communication servers, and the exchanges participants computers (client). The host constitutes, so to speak, the heart of the electronic trading system. The hosts operations includes, for example, order-matching, maintaining order books and positions or price information. Participants, e.g., traders, are capable of communicating with the host by means of high speed data lines, high speed communications servers and the Internet. Thus, the traders can participate in the market by means of the clients communicating with the host. 
   In order to secure system availability, the exchange&#39;s system often uses two servers placed in two geographically different spots interconnected via a network. One of the servers is considered being the primary server and the other consequently as the secondary. The system will be operational with only one server acting as primary, but will then, of course, not be redundant. The primary server will accept incoming messages, store them to disk (i.e., a disk unit) in a log file and replicate the message to the secondary node or server. The two servers then perform the same business logic procedure based on the incoming message. This results in the two servers being synchronized and having the same application state, i.e., each transaction has the same state with respect to, for example, price or volume of a stock. If the primary server fails for some reason, the secondary server is accordingly able to take over and take the role as primary node and accept incoming messages. On the other hand, if the secondary server fails for some reason, the primary server just continuous to operate. 
   In order to be able to access data in such a system, such as user data (e.g., data regarding e-mail address and telephone number of a specific user), or instrument data (e.g., data regarding traded instruments), in a structured and efficient way, such data is stored in SQL databases connected to the servers. This data is used by the business logic of the servers during the processing of incoming messages i.e., transactions. When a server receives an updating message, i.e., a message containing a number of updating instructions (e.g., add a new user or add a new instrument), the database is updated according to the instructions in the updating message. The updating operations, i.e., the new information, is not permanently stored in the database until they are committed or confirmed, i.e., a command making all data modifications performed since the start of the updating operation a permanent part of the database. If the database or a server should fail for some reason before an operation, i.e., an updating, has been committed, the updated information will thus be lost since it not has become a permanent part of the database yet. Consequently, a large number of committing operations will have to performed in order to assure reliable in service, or in other words, to assure that no updating data is lost in case of failure of the database or the server. Each committing operation is time-consuming and puts a load on the databases and the servers. If a large number of updating messages is received and/or updating messages containing a large number of updating operations, the required committing operations may introduce significant time delays and/or significant load on the database and thus the performance of the system may be periodically degraded. 
   Thus, there is need of an improved method for a trading system. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved method for a trading system that enhance the performance of the system. 
   The present invention provides an improved method for a trading system that is capable of updating a database in a more efficient way in terms of system load. 
   Furthermore, the present invention provides an improved method for a trading system that is capable of updating a database in a more efficient way in terms of time consumption. 
   This may be achieved according to the present invention by providing a method, a computer program, and a computer readable medium having the features defined in the independent claims. Embodiments of the present invention are defined in the dependent claims. 
   According to a first aspect of the present invention, there is provided a method for a computer system communicating with a plurality of clients, which system includes at least a server, wherein the server receives incoming messages of the system, the server being connected to a database for storing information according to instructions of the incoming messages, the method comprising the steps of: receiving updating instructions via incoming messages; storing the incoming messages in a file having a horizontal file structure; updating the database by performing updating operations according to the instructions of the messages; and performing a committing operation of all updating operations performed since the last committing operation at predetermined intervals in order to make all data modifications performed since the start of the last committing operation a permanent part of the database. 
   According to second aspect of the present invention, there is provided a computer program product which, if executed on a computer, performs steps in accordance with the method according to the first aspect. 
   According to a third aspect of the present invention, there is provided a computer readable medium comprising instructions for bringing a computer to perform the method according to the first aspect. 
   The invention is based on the idea of storing incoming updating messages in a horizontal file structure, updating the database with the operations instructed by the received messages but only perform a committing operation in the database at predetermined intervals. Thus, the database is updated with a number of operations, for example add a user, as instructed by the received updating messages stored in the horizontal structure. The result of these operations is visible to the business logic even though the operation are not committed, i.e., a command making all data modifications performed since the start of the updating operation a permanent part of the database. That is, the business can access updated information of the database which not yet have been committed. Due to the fact that the operations performed in the database is committed only at regular intervals the performance of the system can be enhanced. Accordingly, it is possible to access data, i.e., updating of the information of the database, in a structured way the same time as the number of I/O-operations (writing operations) are significantly reduced. Furthermore, if the database or server should fail for some reason, the information that not yet has been committed in the database, i.e., permanently stored in the database, can be recovered from messages stored in the horizontal file. Thereby, the performance of the system can be improved, the message handling can be significantly improved and the risks for latencies can be decreased. 
   Thus, the present invention is based on the insight that the business logic of a server can access the updated information of the database without the commitment being made. That is, if the business logic looks for, for example, a new user that is stored in the database but the storage of the message containing the updating information regarding this new user has not been committed, the business logic is able to find the new user. In other words, for the business logic it makes no difference whether the message has been committed or not. 
   As realized by the person skilled in the art, the methods of the present invention, as well as preferred embodiments thereof, are suitable to realize as a computer program or a computer readable medium. 
   The features that characterize the invention, both as to organization and to method of operation, together with further objects and advantages thereof, will be better understood from the following description used in conjunction with the accompanying drawings. It is to be expressly understood that the drawings is for the purpose of illustration and description and is not intended as a definition of the limits of the invention. These and other objects attained, and advantages offered, by the present invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     In the following description of an embodiment of the invention, reference will be made to the accompanying drawings of which: 
       FIG. 1  is a general view of an electronic trading system in which the present invention can be implemented. 
       FIG. 2  shows schematically the general principles of the method according to the present invention. 
       FIG. 3  is a flow chart showing steps of an embodiment of the method according to the present invention. 
       FIG. 4  is a flow chart showing steps of the embodiment of the method according to the present invention shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following there will be discussed embodiments of the method for efficient handling of incoming transaction in a computer system. It should be noted that, even if the embodiments discussed hereinafter are shown as being implemented within the contents of an electronic trading system, the present invention can be implemented in practically all transaction burdened computer systems, as the skilled man within the art also easily realizes. 
   With reference first to  FIG. 1 , an electronic trading system in which the present invention can be implemented will be discussed. A number of clients, here indicated by client A  12   a , client B  12   b , and client C  12   c , communicates with the trading or exchange system  10 . Thus, traders can participate in the market by means of the clients  12   a - 12   c  communicating with the exchange system  10 , i.e., the host. The clients  12   a - 12   c  may link to the system  10  via high speed data lines, high speed communication servers, or the Internet. High speed data lines establish direct connection between a client and the system. Connection can also be established between the client and the system by configuring high speed networks or communication servers at strategic access points in locations where traders physically are located. Internet is a third communication means enabling traders, using, for example, the clients  12   a - 12   c , to communicate using, for example, high speed data lines connected to the Internet. Hence, trades are allowed to be located anywhere they can establish a connection to the Internet. 
   The system  10  comprises a receiving gateway  14  arranged to receive incoming messages from the clients  12   a - 12   c  and distribute them to a server  16   a  acting as the primary node. In order to secure system availability, the exchange&#39;s system often uses two servers placed in two geographically different spots interconnected via a network. One of the servers is considered being the primary server and the other consequently as the secondary. The system will be operational with only one server acting as primary, but will then, of course, not be redundant. A storage means  18   a , e.g., a SQL database, is connected to the primary server  16   a  and contains, inter alia, information regarding, for example, users and traded instruments. This database  18   a  may be of course be physically separated from the server  16   a . The secondary server  16   b  is hence connected to the primary server  16   a , and incoming messages is distributed to the secondary server  16   b  via the primary server  16   a . A storage means  18   b , e.g., a SQL database, is connected to the secondary server  16   b  and contains, inter alia, information regarding, for example, users and traded instruments. This database  18   b  may be of course be physically separated from the server  16   b . The two servers  16   a ,  16   b  perform the same business logic procedure based on incoming transaction messages in the business logic units  20   a  and  20   b , respectively. This results in the two servers being synchronized and having the same application state. If the primary server fails for some reason, the secondary server is accordingly able to take over and take the role as primary node and accept incoming messages. On the other hand, if the secondary server fails for some reason, the primary server just continuous to operate. The business logic  20   a  and  20   b  utilizes information stored in the databases  18   a  and  18   b , respectively, when processing transactions, for example, in order to check whether a specific user is permitted to perform a certain transaction. 
   According to the conventional technique, the primary server  16   a  receives incoming updating messages containing a number of updating instructions for the database  18   a , e.g., add a new user or change an address of an user, via the receiving application  14  from a client  12   a - c . These updating messages are stored in a memory  17   a  persistently, for example, a transaction log file in a non-volatile memory, such as a magnetically or optically readable disk. Received updating messages may also be distributed to the secondary server  16   b  for updating of the database  18   b  connected to the secondary server  16   b . Each updating message contains, as mentioned above, a number of database updating instructions, each instruction causing an updating operating in the database  18   a . The updating operations is not permanently stored in the database until they are committed or confirmed, i.e., a command making all data modifications performed since the start of the updating operation a permanent part of the database. If the database  18   a  or the server  16   a  should fail for some reason before an operation, i.e., an updating, has been committed, the updated information will be lost since it not has become a permanent part of the database yet. Thus, a large number of committing operations will have to performed in order to assure that no data is lost. 
   As mentioned above, the first server  16   a  has also access to a file having horizontal file structure, such as a flat file, in the memory  17   a  and the second server  16   b  has also access to a memory  17   b , for example, a transaction log file in a non-volatile memory, such as a magnetically or optically readable disk, including a file having horizontal file structure, such as a flat file. The first and second server  16   a  and  16   b , respectively, are capable of storing messages in the flat file in the memory  17   a  and  17   b , respectively. The messages are stored in sequence number order, i.e., in the order they are received. Thus, the storage is fast and no confirmation that the message has been stored is received. 
   Turning now to  FIG. 2 , the general principles of the present invention will be described. As mentioned above, even the embodiments discussed with reference to  FIG. 2  and hereinafter in connection with  FIGS. 3-6  are shown as being implemented within the contents of the electronic trading system shown in  FIG. 1 , the present invention, as the skilled man within the art easily realizes, can be implemented in practically all transaction burdened computer systems. Furthermore, the method according to the present invention is described as being implemented in the first server  16   a , but, as the skilled man within the art realizes, the method can also or instead be implemented in the second server  16   b.    
   First, at step  30 , an new incoming updating message containing updating instructions for the database  18   a  (and the database  18   b ) is received, for example, from a client  12   a ,  12   b ,  12   c . Then, at step  32 , the received message is stored in a file having a horizontal file structure, for example, in a flat file of the memory  17   a . Thereafter, at step  34 , the database  18   a  is updated in accordance with the instructions of the message, for example, a new user is added. It should be noted that the business logic  20   a  has access to the new information, i.e., the updated information, even though the information has not been committed. At step  36 , a check whether a predetermined interval since the last committing operation has elapsed. If no, the algorithm returns to step  30 . If yes, the algorithm proceeds to step  38 , where a committing operation is executed in order to make all data modifications performed since the last of the committing operation a permanent part of the database. Due to the fact that the committing operation is performed at predetermined intervals, the updating operations of a number of messages is performed each committing operation. Thereby, the process may enhance the performance of the system. 
   According to an embodiment, the sequence numbers of the messages received since the last committing operation is committed in the database when a committing operation of all updating operations is performed. For example, the sequence number are stored in a table of the database. Thereby, it is possible to check which updating operations that should be committed in the database at the committing operation. For example, the sequence numbers of the messages stored in the horizontal file structure can be checked and compared with the committed sequence numbers in order to identify whether a predetermined number of messages has been received since the last operation of committing was performed. As an example, the committing operation may be executed when 1000 messages has been received. That is, when the database has been updated according to the instructions of the last 1000 messages, the committing operation is performed in order to make all these data modifications performed since the last of the committing operation a permanent part of the database. 
   Another embodiment of the present invention will now be discussed with reference to  FIGS. 3 and 4 . Turning to  FIG. 4 , at step  40 , the system  10  operates according to normal procedures, i.e., according to the procedure outlined with reference to  FIG. 2 . Then, at step  42 , a failure of the database  18   a  and/or the database  18   b  and/or the server  16   a  and/or the server  16   b  is identified. This means that all updates and/or modifications performed in the database (-s) but not committed yet will be lost. In this case the algorithm proceeds to step  44 , where a recovery operation is performed in order to recover all updates and/or modifications performed in the database (-s) but not committed at the failure. With reference to  FIG. 4 , the recovery procedure will be described. First, at step  50 , the highest sequence number of the messages stored in the flat file  17   a  is checked. Then, at step  52 , the highest committed sequence number of the data base is checked. In step  54 , these two sequence numbers are compared and then, in step  58 , it is determined whether the sequence number of the flat file is higher than the sequence number of the database. If the sequence number of the database is higher, the procedure returns to step  40 . On the other hand, if the sequence number of the flat file  17   a  is higher, the algorithm proceeds to step  58  where a committing operation is performed in order to commit updating according to instructions in messages stored in the flat file having higher sequence numbers than the highest committed sequence number of the table of the database. Thereby, all information that was lost when the database failed can be recovered. 
   It should be noted that even though the procedures discussed above have been described with reference to the database connected to the primary server  18   a , the skilled man in the art realizes that they also can be utilized in the database  18   b  connected to the secondary server  16   b.    
   Although specific embodiments have been shown and described herein for purposes of illustration and exemplification, it is understood by those of ordinary skill in the art that the specific embodiments shown and described may be substituted for a wide variety of alternative and/or equivalent implementations without departing from the scope of the invention. Those of ordinary skill in the art will readily appreciate that the present invention could be implemented in a wide variety of embodiments, including hardware and software implementations, or combinations thereof. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Consequently, the present invention is defined by the wording of the appended claims and equivalents thereof.