المتغيرات في لغة الجافا

التعرف على اهم انواع المتغيرات في لغة الجافا مع بيان كيفية اجراء العمليات الحسابية المختلفة عليها والتعرف على كيفية السماح للمستخدم بادخال قيم للمتغيرات من لوحة المفاتيح مع القيام بتخزينها.

التعرف على المبادئ الأساسية اللازمة لكتابة برنامج بلغة الجافا

التعرف على الهيكلية العامة اللازمة لكتابة برنامج بلغة الجافا مع شرح أولي لمجموعة من المفاهيم المستخدمة مثل :الكلاسات (الصفوف ), التوابع, انواع المتغيرات, الكلمات المحجوزة, التعليقات و سلاسل الهروب. بالاضافة الى التعرف عن كيفية انشاء مشروع جديد بلغة الجافا باستخدام المنصة Eclipse.

Development of Distributed Partitionable Reliable Applications using Jgroup/ARM

The increasing reliance on network systems in day-to-day activities requires that they provide available and reliable services. Jgroup provides available service through creating multiple replicas of the same service on multiple devices. Jgroup achieves reliable service by maintaining the shared state between the replicas and coordinating their activities through Remote Method Invocation. Unlike Jgroup, JavaGroups uses message passing to implement coordination between the replicas. In this paper, we compare Jgroup and JavaGroups for different Group Method Invocation modes. These modes are Anycast and Multicast in Jgroup, GET_FIRST and GET_ALL in JavaGroups. This paper also improves the performance of ARM (Autonomous Replication Management) which is embedded with Jgroup (Jgroup/ARM) for supporting fault tolerance, through finding a new solution to handle group failure where all remaining replicas fail in rapid succession. In this new solution, only one replica (the group leader) issues renew events (IamAlive) periodically, instead of sending it by every replica in the group, with taking the same period to discover group failure by Replication Manager. Results of Comparison show that JavaGroups is faster than Jgroup when a single replica is used, whereas Jgroup outperforms JavaGroups with increasing number of replicas. The invocation delay in JavaGroups increases noticeably with increasing the size of array passed into the invoked method which make JavaGroups unsuitable for applications which require exchanging big sizes of data and use large number of servers, whereas Jgroup is suitable for that. Results show that the new proposal reduces the number of renew events to 37.5% at most, and Jgroup/ARM takes approximately the same period of time to discover group failure as in Meling solution.