Concurrent operations in a distributed and mobile collaborative environment

Abstract

In a distributed groupware system, objects shared by users are subject to concurrency and real-time constraints. In order to satisfy these, various concurrency control algorithms [4] [10] [18] have been proposed that exploit the semantic properties of operations. By ordering concurrent operations, they generally guarantee consistency of the different copies of each object. However, in some situations they can result in inconsistent copies, a non-respect of user's intentions, and in the need to undo and redo some operations.The principle objective of this paper is to present an algorithm that overcomes these drawbacks in distributed and mobile collaborative environments. The algorithm is based on the notion of user's intention, and also on the construction of equivalent histories by exploiting and combining some general semantic properties such as forward/backward transposition.

Customizable Collaborative Editor Relying on treeOPT Algorithm

“…The transformations are performed in such a manner that the intentions of the users are preserved and, at the end, the copies of the documents converge. Various operational transformation algorithms have been proposed: dOPT (Ellis and Gibbs, 1989), adOPTed (Ressel et al, 1996), GOT , GOTO (Sun and Ellis, 1998), SOCT2 (Suleiman et al, 1997;Suleiman et al, 1998), SOCT3 and SOCT4 (Vidot et al, 2000). Although these algorithms are generic operational transformation algorithms, they can be applied only for applications that use a linear representation of the document.…”

“…The transform function should be replaced with the part of dOPT algorithm for executing a causally ready operation (Ellis and Gibbs, 1989). When combined with SOCT2, the algorithm has to be adapted to the mechanism of integrating an operation into the history by performing forward and backward transpositions (Suleiman et al, 1998).…”

Symbolic Model-Checking of Optimistic Replication Algorithms

“…Several integration procedures have been proposed in the groupware research area, such as dOPT [4], adOPTed [8], SOCT2,4 [10,14] and GOTO [11]. Every site generates operations sequentially and stores these operations in a stack also called a history (or execution trace).…”

Awareness of Concurrent Changes in Distributed Software Development

“…Procedure merge computes list H, the result of merging of LL, RCL and RUL. List RCL is first appended to H. Each operation O in LL and in RUL is integrated in turn into H. For the integration mechanism we use the SOCT2 [8] algorithm. Procedure transformSOCT2 reorders the list of operations L such that operations that causally precede O are situated in L before operations that are concurrent with O.…”