ns2 project in Quebec

ns2 project in Quebec


ns2 project in Quebeca  data or control

dependency exists between the successive tasks, which imposes ns2 project in Quebec a precedence requirement on their scheduling. The sequences of tasks may span multiple processors and one simple task can belong to more than one end-to-end task. Tasks are the units of scheduling in the computational model,ns2 project in Quebec but they are not the only components of the model.

In fact, because we consider the possibility of a certain level of complexity in the tasks, we also consider the blocks of code executed within the tasks in the computational model. In the ns2 project in Quebec simplest case, only one block of code corresponds to the whole code of one task. The existence of computational units ns2 project in Quebec within the task in our model will also permit the construction of a more detailed behavioural

model to support the analysis of end-to-end tasks, as will be shown below.

The analysis of the behaviour ns2 project in Quebec of the end-to-end transactions

is supported by a behavioural model that clearly explains

the way the sequences of activities take place.

To describe the temporal ns2 project in Quebec behaviour of PDES in terms

of events, delays and actions, several approaches or be- havioural models can be employed: models based on eventordering graphs such as execution graphs [18] and Petri

Nets [11]; structured models based on state machines such

as the control flow of Hatley and Pirbai [5]; and models

based on process ns2 project in Quebec algebras such as CSP [6]. A model based

on an event-ordering graph has been selected as the behavioural

model for this research work. The selection was

made as a result of its simplicity and wide applicability.

The model is composed of two main elements [23]: 1)

Activities, which are represented by ns2 project in Quebec a sequence of three

events: Ready, when the activity is ready to start; Begin,

when it starts; and End, when it finishes; and 2) A set

of precedence and synchronization relationships defined on

the ready and end events, which ns2 project in Quebec establish partial ordering

for a group of activities. These relationships give rise to

the kinds of activities represented in Figure 1. SEQuence

implies chains of communicating activities in a transaction.

SYNchronization implies activities ns2 project in Quebec that also communicate

with activities belonging to other transactions. ALTernation

implies a group of alternative activities in a transaction (supported

by blocks in the same or different tasks) where only

one activity has place on each instance of the transaction.

REPlication implies the same ns2 project in Quebec  order as ALTernation, but in

this case the activities are replicas (activities with the same

function and code) useful to increase the throughput of the

transaction. Finally, PARallel implies activities in a transaction, developed in

parallel in different processors.