Web Services Support for Dynamic Business Process Outsourcing

Outsourcing of business processes is crucial for organizations to be effective, efficient and flexible. To meet fast-changing market conditions, dynamic outsourcing is required, in which business relationships are established and enacted on-the-fly in an adaptive, fine-grained way unrestricted by geographic distance. This requires automated means for both the establishment of outsourcing relationships and for the enactment of services performed in these relationships over electronic channels. Due to wide industry support and the underlying model of loose coupling of services, Web services increasingly become the mechanism of choice to connect organizations across organizational boundaries. This paper analyzes to which extent Web services support the dynamic process outsourcing paradigm. We discuss contract -based dynamic business process outsourcing to define requirements and then introduce the Web services framework. Based on this, we investigate the match between the two. We observe that the Web services framework requires further support for cross - organizational business processes and mechanisms for contracting, QoS management and process-based transaction support and suggest ways to fill those gaps

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Performance analysis of data sharing environments

A data sharing environment consists of multiple loosely coupled transaction processing nodes sharing a common database at the disk level. Apart from the private buffers in each node, the environment may contain an additional global shared buffer in the form of disk cache, file server cache or intermediate shared memory. In this dissertation, we develop a comprehensive analytical model for such a complex environment using a hierarchical approach, where the concurrency control, the CPU queueing discipline and the buffer hit probabilities of the private and shared buffers are first modeled separately, and then integrated through an iterative procedure. To this end, we develop two new submodels: (1) the private buffer model that captures the effects of multi-system buffer invalidation, skewed database access, LRU buffer replacement policy and the rerun transactions, and (2) the shared buffer modeling framework that captures the effects of dependence between the contents of private and the shared buffers, and is used to analyze various shared buffer management policies (SBMPs) proposed in this dissertation. The various policies propagate a granule into the shared buffer after one or more of the following events: database update, shared buffer miss and private buffer replacement. The analytical model is then used to investigate various issues in the design of data sharing environment. Scalability. The model predicts degradation in transaction response time as new nodes are added to the system. Buffer utilization. The model predicts the effectiveness of additional buffer allocation for both the private and shared buffers. Skewed access. The skewed access increases both data contention and buffer hit probability in the system. The resultant effect on the transaction response time is investigated. The response time is found to be more sensitive to skewed data access under two-phase locking (2PL) than under optimistic concurrency control (OCC) protocol. The skewed access also magnifies the effect of invalidation and reduces the utilization of private buffers. Policy selection. The modeling framework is used to select the best SBMP for a given parameter range (private and shared buffer sizes, shared buffer access overhead and delay, number of nodes, database access pattern, update probabilities, etc.). The updates should always be propagated to the shared buffer to alleviate the invalidation problem. For a smaller number of nodes, the effect of dependence between the contents of the private and the shared buffers influences policy selection. Optimal configuration. The model can be used to optimally allocate the buffer between the private and the shared buffers in various system architectures depending on the overhead and delay in accessing the shared buffer. For a larger number of nodes and under skewed database access, the shared buffer can improve the transaction response time significantly

Buffer Management Policy for an On-Demand Video Server

In an on-demand video server environment, multimedia objects (e.g. movies) are very large and are read sequentially. Hence it is not economical to cache the entire object. However, caching random fractions of a multimedia object is not beneficial. This is due to the stringent response time requirements where continuous availability of a stream has to be guaranteed; whereas caching random fractions will result in unpredictable load on the disks. Therefore, traditional buffer management policies such as LRU are not effective. In addition, the sequential access implies pages brought in by a stream can be reused by a closely following stream and subsequently discarded, thus buffering only a fraction of the entire object. In this paper, we propose a buffer management policy called the interval caching policy based on the above idea that identifies certain streams and temporarily buffers the pages brought in by those streams. We study the efficacy of this technique for reducing disk overload..

Scheduling Policies for an On-Demand Video Server with Batching

In an on-demand video server environment, clients make requests for movies to a centralized video server. Due to the stringent response time requirements, continuous delivery of a video stream to the client has to be guaranteed by reserving sufficient resources required to deliver a stream. Hence there is a hard limit on the number of streams that can be simultaneously delivered by a server. The server can satisfy multiple requests for the same movie using a single disk I/O stream by sending the same data pages to multiple clients (using the multicast facility if present in the system). This can be achieved by batching requests for the same movie that arrive within a short duration of time. In this paper, we consider various policies for selecting the movie to be multicast. The choice of a policy depends very much on the customer waiting time tolerance before reneging. We show that an FCFS policy that schedules the movie with the longest outstanding request can perform better than the ..