SAP implementation | EPFL Graph Search

SAP implementation (Systems, Applications & Products implementation) refers to the name of the German company SAP SE, and is the whole of processes that defines a method to implement the SAP ERP enterprise resource planning software in an organization. The SAP implementation method described in this entry is a generic method and not a specific implementation method as such. It is based on best practices and case studies from various literature sources and presents a collection of processes and products that make up a complete implementation method to allow any organization to plan and execute the implementation of SAP software. Introduction The implement of SAP software, such as SAP R/3 is almost always a massive operation that brings a lot of changes in the organization. The whole process can take up to several years. Virtually every person in the organization is involved, whether they are part of the SAP technical support organization (TSO) or the actual end-users of the

Strategies for Delay-Limited Source-Channel Coding

Marius Kleiner

In point-to-point source-channel communication with a fidelity criterion and a transmission cost constraint, the region of achievable cost and fidelity pairs is completely characterized by Shannon's separation theorem. However, this is in general only true if coding of arbitrary complexity and delay is admitted. If the delay is constrained, the separation theorem only provides an outer bound to the achievable cost/distortion region, and the exact shape of this region is in general not known. The first part of this thesis studies source-channel communication when neither a required average fidelity nor a cost constraint are specified, but when the goal is to maximize the ratio of fidelity to cost. It is shown how the maximal ratio relates to existing quantities such as the capacity per unit cost. Finally, necessary and sufficient conditions are derived to test whether a given system operates at this maximal ratio and when this is possible using a single-letter code. The second part of the thesis studies communication of continuous-valued sources over the additive white Gaussian noise channel when only a single source symbol is to be encoded at a time. In particular, the case is considered where several uses of the channel can be made for each source symbol. Inspired by communication with feedback, a simple communication strategy combining quantization and uncoded transmission is derived and analyzed. It is shown that this strategy achieves a mean squared error that performs as well as any known communication strategy that encodes a single source symbol at a time. On the other hand, it is strictly suboptimal in the sense that the gap (in dB) between the achievable signal-to-distortion ratio (SDR) and the best SDR achievable without a delay limit grows with increasing signal-to-noise ratio. The thesis turns to a more practical subject in its last part. The case is made why object-oriented programming is particularly suited to implementing simulations. As a proof of concept, a complete implementation of an object-oriented simulator for source-channel coding is presented that allows for rapid development and analysis of arbitrary communication strategies.

EPFL2010

Deadlock Immunity

Horatiu Jula

Deadlock immunity is a property by which programs, once afflicted by a deadlock, develop resistance against future occurrences of that deadlock. We enable real applications to automatically achieve immunity against deadlock bugs involving mutex locks, semaphores, read-write locks, class initialization, and external synchronization, with no user intervention, and without changing the semantics of the applications. In other words, we provide transparent, non-intrusive immunization against deadlocks. Our deadlock immunity system, called Dimmunix, is available for Java applications, C/C++ applications using POSIX Threads, and Android OS. Java Dimmunix provides application-level immunity, i.e., deadlock immunity to individual Java applications. POSIX Threads Dimmunix provides library-level immunity, i.e., deadlock immunity to all the C/C++ applications using the POSIX Threads library. Android Dimmunix provides platform-level immunity, i.e., deadlock immunity to all the applications running within the Android OS. We also developed, on top of Java Dimmunix, a collaborative deadlock immunity framework called Communix, in which machines connected to the Internet collaborate to immunize each other against deadlocks. Since mutex locks are likely the most widely used synchronization construct, we focus on mutex deadlocks, i.e., deadlocks involving mutexes. The Java Dimmunix prototype is a complete implementation of Dimmunix; the other prototypes handle only mutex deadlocks. We heavily optimized the part of the Java Dimmunix prototype responsible for mutex deadlocks, in order to efficiently handle synchronization-intensive applications. Our prototype implementations are effective against deadlocks reported in real applications, like Limewire, MySQL JDBC, ActiveMQ, MySQL Server, and SQLite. The Java Dimmunix prototype for mutex deadlocks runs efficiently on synchronization-intensive applications, like JBoss and Eclipse, with millions of lines of code and hundreds of threads. We also show that Java Dimmunix for non-mutex deadlocks, POSIX Threads Dimmunix, Android Dimmunix, and Communix are efficient. Moreover, the Communix prototype manages to contain denial of service attacks that attempt to exploit the collaborative immunization framework.

EPFL2011

Strategies for Delay-Limited Source-Channel Coding

Marius Kleiner

EPFL2010

Deadlock Immunity

Horatiu Jula

EPFL2011