5.4 The conflict management

Conflicts which are occuring at the synchronisation of data from time silmultaneous modifications in the involved systems. These can be fixed for instance by definition of a priority. Simultaneously refers hereby on a time span between two synchronisations.

The basis of conflict verification in the SIS is a modification information which will be made available by the connection plugin during the synchronisation und the data image which saves the modification information of the last synchronisation. The conflict verification will be implemented during the synchronisation by the particular process with its data images. The procedure is as follows:

• Verification of the modification information between source and data image. Furthermore, this verification is required in order to avoid a "Ping-Pong" of modifications between the systems.
• Verification of the modification information between target and data image.

The conflict solution will be defined for each process individually. The following options are available:

• Source has priority - The data will be written und all data images will completely or single-sided be updated.
• Target has priority in the current implementation  - The data will not be written and only the own data image will be updated (establish conflict liberty).
• Skip - The processing of the record will be cancelled without adapting a data image.
• Write, but leave conflict for other processes  - The data will be written and the own data image will be updated, foreign data images will not be updated.
• Only write source modifications, but leave conflict for other processes - The in the source changed data will be written and the own data image will be updated, foreign data images will not be updated. For the change recognition, a copy of the record is required in the data image. In case, this is missing, all data will be written.

It needs to be considered at the conflict solution that processes which affect the same data areas, will not be implemented parallely. Therefore, it is guaranteed that the update of parallel and complementary data images does not overlap with the implementation of the related process.

The following example shows the involved information and the procedure of the conflict handling. Hereby, we define two processes which realise the bidirectional synchronisation and a third process which carries out an asymmetric transfer.

Initial situation of the records and data images

The conflict situation

The time silmultaneous modifications are marked in red.

The conflict solution by the process 1

The process 1 will save the data by the conflict handling "Source has priority". The data images will thereby updated as follows:

Process 2 and 3 find the updated data images during its implementation and do not recognise a conflict anymore.

This is also the standard update for the conflict free case.

The conflict solution by the process 2

The process 2 will not save the data by its conflict handling "Target has priority in the current implementation". The data images will thereby be updated as follows: The synchrony will be established afterwards by the complementary process if applicable in case, it is including a writing solution.

The update of the data image is required in this situation in order to avoid a locked situation.

The conflict solution by the process 3

The process 3 will the save the data by its conflict handling "Write, but leave conflict for other processes". The data images will thereby be updated as follows:

By this setting, only the own data image will be adapted in case of a conflict. Therefore, the conflict solution is with the other processes.