Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F9/00—Arrangements for program control, e.g. control units
  • G06F9/06—Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
  • G06F9/46—Multiprogramming arrangements
  • G06F9/466—Transaction processing

Definitions

• the invention relates to the field of information transmission between suppliers and consumers through a chain of communication channels. More particularly, the invention consists in carrying out this transmission asynchronously while respecting the so-called ACID properties.
• An asynchronous communication service includes a manager and one or more communication channels.
• a supplier (customer of the service) transmits the information by addressing a specific channel.
• the channel transfers information to the consumer
• the channel acts as an intermediary between two customers by decoupling the transmission of information on one side and the other. We must be able to deliver information reliably while maintaining desynchronization between suppliers and consumers.
• a known solution for transmitting data reliably is based on transaction systems.
• a transaction is initiated by the data provider, then is "propagated" to intermediate elements (communication channels) to finally reach the consumer. Once the data has been delivered, and before confirming the modifications made (data delivery), the properties linked to the execution of the transaction are checked.
• Asynchronous communication channels imply a desynchronization between suppliers and consumers while transactions require synchronization to enable end-to-end tracking of transaction stability properties.
• a transaction must satisfy four properties grouped under the acronym ACID meaning: Atomicity, Coherence, Insulation and Durability. These four properties are closely related. The competition control and takeover mechanisms implemented by a transactional engine aim to enforce them.
• the atomicity guarantees that either all of the updates to a transaction are made, or none of these updates are made. Failure to comply with this property can lead to all the data evolving from the initial coherent state to an incoherent state.
• any series of actions constituting a transaction is marked by a beginning and an end.
• the start of a transaction signals the transaction start event to the transaction engine.
• Two orders are provided to mark the end of a transaction:
• the consistency property concerns the semantic consistency of a data set.
• the maintenance of this can be partly ensured by the mechanisms ensuring the control of integrity constraints and by the maintenance of the ownership of the transactions.
• Isolation is essential in a multitasking environment, to ensure that each transaction sees a consistent state of all of the data. Isolation consists in ensuring that if the transaction is executed in parallel with other transactions (accessing a common set of data), there is a serial execution of the same transactions which would produce the same changes to the data set accessed by transactions. In this case, the isolation property is checked for this set of transactions.
• Durability ensures that updates to a committed transaction are final.
• the only action which must make it possible to undo the updates of a validated transaction is the execution of a compensation transaction. This property goes hand in hand with the atomicity property stipulating that the updates of a transaction form a coherent whole which is either abandoned as a whole, or validated durably.
• a method of implementation in the event of memory or disk failure resulting in the loss of part of the information in the database, consists of having a recovery mechanism to recover the lost information.
• a transaction can be initiated and guarantee from the information provider to the consumer that the ACID properties are respected.
• the actions guaranteeing these properties must interact with each other in a reliable and determined manner, depending on the quality of service desired.
• the object of the invention is therefore to provide an asynchronous communication system having ACID properties.
• the subject of the invention is a method of asynchronous transmission of information between a supplier and a consumer, in accordance with the ACID properties, the supplier and the consumer being connected by a chain of communication channels.
• This process is characterized in that the information is transmitted by means of established independent transactions:
• Another subject of the invention is a communication channel, allowing the asynchronous transmission of information between a supplier and a consumer, in accordance with the ACID properties.
• This channel has a set of customers, which can be other communication channels and / or consumers and it is characterized in that it comprises:
• the supplier initiates a transaction only with the first communication channel in the chain. Also, he will very quickly obtain the result (“commit” or “Abort”) of this transaction, and will not remain blocked while awaiting the delivery of information to the consumer. In other words, the objective of asynchronous transmission is achieved.
• Figure 1 shows the general principle of a transaction chain according to the invention.
• FIG. 2 shows an example of a communication network implementing communication channels according to the invention.
• a transaction is initiated by a supplier, referenced 1, destined for a communication channel 2.
• This transaction includes at least the information that the supplier wishes to transmit to consumers 5.
• the communication channel then stores this information in a reliable memory 4.
• this reliable memory can be a database having an XA interface and the necessary recovery mechanisms.
• the transaction which was initiated by the supplier 1 is finalized. If this finalization is successful (which conventionally corresponds to the sending of a "commit" message to the supplier), the information contained in the transaction is stored in queues 6.
• a client of the channel can be a consumer as is the case in this example, or another communication channel. In the example in FIG. 1, there are therefore two queues, each one being associated with one of the two consumers 5.
• the information is stored in the queues before finalizing the transaction, but it is only made available (for example by means of an availability identifier associated with each queue) when this finalization has been successful.
• an execution thread exists for each consumer virtually connected to the channel.
• the role of these execution threads is to consume the information stored in the queues 6 in order to initiate transactions with the clients of the communication channel.
• These customers can be consumers 5, or possibly other communication channels.
• These transactions contain the information stored in the queues, which was previously received from provider 1. Information is thus transmitted along the chain.
• the reliable storage is never used in reading.
• the reliable memory is typically a database, it is understood that any access is penalizing in terms of speed of execution. This method therefore makes it possible to minimize access to reliable memory, by the use of much faster queues, and consequently to accelerate the speed of transmission of information from the supplier to consumers.
• each software element provides a standard recovery interface for failure recovery.
• This interface allows you to undo the actions made by a failed transaction.
• the reliable memory provides an interface which makes it possible mainly to remove information relating to a transaction from storage. Thus, if one of the transactions in the chain fails, all of the actions taken on the objects involved in the transaction in question are undone. Once the actions are undone due to the failure of a transaction, the transaction can be started again. by reading the information stored in the reliable memory.
• This solution provides an end-to-end data recovery mechanism, working automatically with an external transaction system. Compared to other solutions, this mechanism is generic.
• a single communication channel is considered, but this mechanism being symmetrical it works in the same way in any chain of channels.
• the number of communication channels between the supplier and the consumer or consumers can be arbitrary.
• a communication channel can connect as a client of another communication channel.
• FIG. 2 illustrates an example of a network of communication channels.
• a supplier F is connected to a first communication channel.
• a supplier F 2 is connected to a second communication channel. These two communication channels have a third communication channel for the client.
• One or more consumers C are connected as customers of the first communication channel, while one or more consumers C 2 are connected as customers of the second communication channel.
• Such a network topology is of great practical interest. It allows consumers C to receive only information from the supplier F 17 while consumers C 2 receive information from the suppliers F and F 2 . Any piece of software can therefore choose to receive information from several suppliers by choosing the communication channel to which he must connect as a customer.

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• Engineering & Computer Science (AREA)
• Software Systems (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Computer And Data Communications (AREA)
• Information Retrieval, Db Structures And Fs Structures Therefor (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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• 2000
  • 2000-08-10 AU AU70109/00A patent/AU7010900A/en not_active Abandoned
  • 2000-08-10 WO PCT/FR2000/002292 patent/WO2001013225A2/fr not_active Application Discontinuation
  • 2000-08-10 JP JP2001517254A patent/JP2003507789A/ja not_active Withdrawn
  • 2000-08-10 EP EP00958660A patent/EP1145121A3/de not_active Withdrawn

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