3 Introductiond

Greedy Routing with Anti-Void Traversal Introduction For Wireless Sensor Networks

1. INTRODUCTION

1.1INTRODUCTION

A wireless sensor network (WSN) consists of sensor nodes (SNs) with wireless

communication capabilities for specific sensing tasks. Due to the limited available

resources, efficient design of localized multihop routing protocols becomes a crucial subject

within the WSNs. How to guarantee delivery of packets is considered an Important issue for

the localized routing algorithms. The well-known greedy forwarding (GF) algorithm is

considered a superior scheme with its low routing overheads.

However, the void problem, which makes the GF technique unable to find its next closer hop

to the destination, will cause the GF algorithm failing to guarantee the delivery of data packets.

Several routing algorithms are proposed to either resolve or reduce the void problem, which

can be classified into non-graph-based and graph-based schemes. In the non graph- based

algorithms the intuitive schemes as proposed in construct a two-hop neighbor table for

implementing the GF algorithm. The network flooding mechanism is adopted Within the GRA

and PSR schemes while the void problem occurs. There also exist routing protocols that adopt

the backtracking method at the occurrence of the network holes . The routing schemes as

proposed by ARP and LFR memorize the routing path after the void problem takes Place.

Moreover, other routing protocols propagate and update the information of the observed void

node in order to reduce the probability of encountering the void problem. By exploiting these

routing algorithms, however, the void problem can only be either

1) Partially alleviated or

2) Resolved with considerable routing overheads and significant converging time.

On the other hand, there are research works on the design of graph-based routing algorithms to

deal with the void problem.

1


GREEDY ANTI-VOID ROUTING (GAR) PROTOCOL

The objective of the GAR protocol is to resolve the void problem such that the packet

delivery from NS to ND can be guaranteed. Before diving into the detail formulation of the

proposed GAR algorithm, an introductory example is described in order to facilitate the

understanding of the GAR protocol. The data packets initiated from the source node NS to the

destination node ND will arrive in NV based on the GF algorithm. The void problem occurs

asNV receives the packets, which leads to the adoption of the RUT scheme as the forwarding

strategy of the GAR protocol. A circle is formed by centering at sV with its radius being equal

to half of the transmission range R=2. The circle is hinged at NV and starts to conduct

counterclockwise rolling until an SN has been encountered by the boundary of the circle, i.e.,

NA. Consequently, the data packets in NV will be forwarded to the encountered node NA.

Subsequently, a new equal-sized circle will be formed, which is centered at sA and

hinged at node NA. The counterclockwise rolling procedure will be proceeded in order to

select the next hop node, i.e., NB in this case. Similarly, same process will be performed by

other intermediate nodes (such as NB and NX) until the node NY is reached, which is

considered to have a smaller distance to ND than that of NV to ND. The conventional GF

scheme will be resumed at NY for delivering data packets to the destination node ND. As a

consequence, the resulting path by adopting the GAR protocol.

2


Fig 1.1.1 Greedy anti-void routing (gar) protocol implementation

3


Proposed Rolling-Ball UDG Boundary Traversal (RUT) Scheme

The RUT scheme is adopted to solve the boundary finding problem, and the

combination of the GF and the RUT scheme (i.e., the GAR protocol) can resolve the void

problem, leading to the guaranteed packet delivery. The definition of boundary and the

problem statement are described as follows:

Definition If there exists a set B _ N such that 1) the nodes in B form a simple unidirectional

ring and 2) the nodes located on and inside the ring are disconnected with those outside of the

ring, B is denoted as the boundary set and the unidirectional ring is called a boundary.

Fig 1.1.2 The proposed RUT scheme.

Partial UDG Construction (PUC) Mechanism

4


The PUC mechanism is targeted to recover the UDG linkage of the boundary node Ni

within a non-UDG network. The boundary nodes within the proposed GAR protocol are

defined as the SNs that are utilized to handle the packet delivery after encountering the void

problem. As shown in Fig. 6, node Ni is considered a boundary node since the converged SP

arc segment exists after Ni conducts the proposed IMS algorithm by the input of the current

one-hop neighbors fN1;N2;N3;N4;Njg. It is noted that the boundary nodes consist of a portion

of the network SNs. Therefore, conducting the PUC mechanism only by the boundary nodes

can conserve network resources than most of the existing flooding-based schemes that require

information from all the network nodes.

Hop Count Reduction (HCR) Mechanism

Based on the rolling-ball traversal within the RUT scheme, the selected next-hop nodes

may not be optimal by considering the minimal HC criterion. Excessive routing delay

associated with power consumption can occur if additional hop nodes are traversed by

adopting the RUT scheme.The void node NV starts the RUT scheme by selecting N1 as its

next hop node with the HCR and the IN mechanisms counterclockwise rolling direction, while

N2 and N3 are continuously chosen as the next hop nodes. Considering the case that N3 is

located within the same transmission range of N1, it is apparently to observe that the packets

can directly be transmitted from N1 to N3. Excessive communication waste can be preserved

without conducting the rerouting process to N2

Intersection Navigation (IN) Mechanism

The IN mechanism is utilized to determine the rolling direction in the RUT scheme

while the void problem occurs. It is noticed that the selection of rolling direction (i.e., either

counterclockwise or clockwise) does not influence the correctness of the proposed RUT

scheme to solve Problem 2, as in Theorem 1. However, the routing efficiency may be severely

degraded if a comparably longer routing path is selected at the occurrence of a void node. The

primary benefit of the IN scheme is to choose a feasible rolling direction while a void node is

encountered.

1.2 Literature

5


We present platypus, an authenticated source routing system routing system built around

the concept of network capabilities, which allow for accountable, fine-grained path selected by

cryptographically attesting to policy compliance at each hop along a source route. Platypus

policy framework that can be used to address several issues in wide-area routing at both the

edge and the core, and evaluate its performance and security. Our result shows that

incremental deployment of platypus can achieve immediate gains.

C#

Language used mostly at the client levels which have the capability of creating

dynamic wed pages. The essential need of VBScript is due to the following requirements.

1. User interaction

2. Data validation

3. Client side utility

FEATURES

i. Interpreted language

ii. Object oriented support

iii. Provides procedural capabilities

iv. Work on event driven model

v. Embedded within ML format

vi. Works on Document Object Model

ELEMENT OF C#

6


i. Variable

ii. Arrays

iii. Control statements

iv. Functions

v. Objects

vi. Events

vii. Delegation

viii. Properties

ix. Interface

x. Exceptions

Client Application Development

Client applications are the closest to a traditional style of application in Windows-

based programming. These are the types of applications that display windows or forms on the

desktop, enabling a user to perform a task. Client applications include applications such as

word processors and spreadsheets, as well as custom business applications such as data-entry

tools, reporting tools, and so on. Client applications usually employ windows, menus, buttons,

and other GUI elements, and they likely access local resources such as the file system and

peripherals such as printers.

Another kind of client application is the traditional ActiveX control (now replaced by

the managed Windows Forms control) deployed over the Internet as a Web page. This

application is much like other client applications: it is executed natively, has access to local

resources, and includes graphical elements.

In the past, developers created such applications using C/C++ in conjunction with the

Microsoft Foundation Classes (MFC) or with a rapid application development (RAD)

environment such as Microsoft® Visual Basic®. The .NET Framework incorporates aspects of

these existing products into a single, consistent development environment that drastically

simplifies the development of client applications.

7


The Windows Forms classes contained in the .NET Framework are designed to be used

for GUI development. You can easily create command windows, buttons, menus, toolbars, and

other screen elements with the flexibility necessary to accommodate shifting business needs.

For example, the .NET Framework provides simple properties to adjust visual

attributes associated with forms. In some cases the underlying operating system does not

support changing these attributes directly, and in these cases the .NET Framework

automatically recreates the forms. This is one of many ways in which the .NET Framework

integrates the developer interface, making coding simpler and more consistent.

Microsoft.NET Framework

The .NET Framework is a new computing platform that simplifies application

development in the highly distributed environment of the Internet. The .NET Framework is

designed to fulfill the following objectives:

FEATURES

Interoperability

Because computer systems commonly require interaction between new and older

applications, the .NET Framework provides means to access functionality that is implemented

in programs that execute outside the .NET environment. Access to com components is

provided in the System.Runtime.InteropServices and System.EnterpriseServices namespaces

of the framework; access to other functionality is provided using the P/Invoke feature.

Common Language Runtime Engine

The Common Language Runtime (CLR) is the execution engine of the .NET

Framework. All .NET programs execute under the supervision of the CLR, guaranteeing

certain properties and behaviors in the areas of memory management, security, and exception

handling.

8


Language Independence

The .NET Framework introduces a Common Type System, or CTS. The

CTS specification defines all possible datatypes and programming constructs supported by the

CLR and how they may or may not interact with each other conforming to the Common

Language Infrastructure (CLI) specification. Because of this feature, the .NET Framework

supports the exchange of types and object instances between libraries and applications written

using any conforming .NET language.

Base Class Library

The Base Class Library (BCL), part of the Framework Class Library (FCL), is a library

of functionality available to all languages using the .NET Framework. The BCL

provides classes which encapsulate a number of common functions, including file reading and

writing, graphic rendering, database interaction, XML document manipulation and so on.

Simplified Deployment

The .NET Framework includes design features and tools that help manage

the installation of computer software to ensure that it does not interfere with previously

installed software, and that it conforms to security requirements.

Security

The design is meant to address some of the vulnerabilities, such as buffer overflows,

that have been exploited by malicious software. Additionally, .NET provides a common

security model for all applications.

9


Portability

The design of the .NET Framework allows it theoretically to be platform agnostic, and

thus cross-platform compatible. That is, a program written to use the framework should run

without change on any type of system for which the framework is implemented. While

Microsoft has never implemented the full framework on any system except Microsoft

Windows, the framework is engineered to be platform agnostic,[5] and cross-platform

implementations are available for other operating systems (see Silverlight and the Alternative

implementations section below). Microsoft submitted the specifications for the Common

Language Infrastructure (which includes the core class libraries, Common Type System, and

the Common Intermediate Language), the C# language, and the C++/CLI language to

both ECMA and the ISO, making them available as open standards.

Asp.Net Architecture

ASP.NET is an important component of .NET Framework. ASP.NET Provides advanced

capabilities, such as efficient database access and easy-to-use Application and Session state

capabilities.ASP.NET application can be created using any .NET language, such as Visual

Basic.NET or Visual C#. NET.

ASP.Net is the latest Microsoft programming framework that allows for the rapid development

of powerful web applications. In this issue of Better Web Design, author going to discuss the

advantages of using ASP. Net. Application Architecture is the most important process of

developing a good application. ASP.NET uses ISAPI to run on the Internet Information Server

(IIS) in Windows 2000 Server. The configuration of ASP.NET is managed by information

stored in XML-format in a configuration file. The cache allows for improved performance of

ASP.NET, as the most commonly requested pages would be served from the ASP.NET cache.

State management services for ASP.NET are provided by the ASP.NET state service.

10


The .NET Framework provides the Common Language Runtime (CLR), which compiles and

manages the execution of ASP.NET code, and the class libraries, which offer pre-built

programmatic functionality for Web Forms, XML support, and exception handling.ADO.NET

provides ASP.NET with connections to databases

The Advantages

Powerful database-driven functionality

Faster web applications

Memory leak and crash protection

Multiple language support

11


Fig 1.2.1 ASP.NET Architecture

12


Features of the Common Language Runtime

The common language runtime manages memory, thread execution, code execution,

code safety verification, compilation, and other system services. These features are intrinsic to

the managed code that runs on the common language runtime.

With regards to security, managed components are awarded varying degrees of trust,

depending on a number of factors that include their origin (such as the Internet, enterprise

network, or local computer). This means that a managed component might or might not be

able to perform file-access operations, registry-access operations, or other sensitive functions,

even if it is being used in the same active application.

Finally, the runtime can be hosted by high-performance, server-side applications, such

as Microsoft® SQL Server™ and Internet Information Services (IIS). This infrastructure

enables you to use managed code to write your business logic, while still enjoying the superior

performance of the industry's best enterprise servers that support runtime hosting.

Assemblies

In the .NET framework, an assembly is a compiled code library used for deployment,

versioning, and security. There are two types: process assemblies (EXE) and library

assemblies (DLL). A process assembly represents a process which will use classes defined in

library assemblies. .NET assemblies contain code in CIL, which is usually generated from

a CLI language, and then compiled into machine language at run time by the CLR just-in-time

compiler.

An assembly can consist of one or more files. Code files are called modules. An

assembly can contain more than one code module and since it is possible to use

different languages to create code modules it is technically possible to use several different

languages to create an assembly. Visual Studio however does not support using different

languages in one assembly.

13


Metadata

.NET metadata, in the Microsoft .NET framework, refers to certain data structures

embedded within the Common Intermediate Language code that describes the high-level

structure of the code. Metadata describes all classes and class members that are defined in the

assembly, and the classes and class members that the current assembly will call from another

assembly. The metadata for a method contains the complete description of the method,

including the class (and the assembly that contains the class), the return type and all of the

method parameters.

A .NET language compiler will generate the metadata and store this in

the assembly containing the CIL. When the CLR executes CIL it will check to make sure that

the metadata of the called method is the same as the metadata that is stored in the calling

method. This ensures that a method can only be called with exactly the right number of

parameters and exactly the right parameter types

Security

.NET has its own security mechanism with two general features: Code Access

Security (CAS), and validation and verification. Code Access Security is based on evidence

that is associated with a specific assembly. Typically the evidence is the source of the

assembly (whether it is installed on the local machine or has been downloaded from the

intranet or Internet). Code Access Security uses evidence to determine the permissions granted

to the code. Other code can demand that calling code is granted a specified permission. The

demand causes the CLR to perform a call stack walk: every assembly of each method in the

call stack is checked for the required permission; if any assembly is not granted the permission

a security exception is thrown.

14


Class Library

The .NET Framework class library is a collection of reusable types that tightly

integrate with the common language runtime. The class library is object oriented, providing

types from which your own managed code can derive functionality. This not only makes

the .NET Framework types easy to use, but also reduces the time associated with learning new

features of the .NET Framework. In addition, third-party components can integrate seamlessly

with classes in the .NET Framework.

For example, the .NET Framework collection classes implement a set of interfaces that

you can use to develop your own collection classes. Your collection classes will blend

seamlessly with the classes in the .NET Framework.

As you would expect from an object-oriented class library, the .NET Framework types

enable you to accomplish a range of common programming tasks, including tasks such as

string management, data collection, database connectivity, and file access. In addition to these

common tasks, the class library includes types that support a variety of specialized

development scenarios.

Server Application Development

Server-side applications in the managed world are implemented through runtime hosts.

Unmanaged applications host the common language runtime, which allows your custom

managed code to control the behavior of the server. This model provides you with all the

features of the common language runtime and class library while gaining the performance and

scalability of the host server.

The following illustration shows a basic network schema with managed code running

in different server environments. Servers such as IIS and SQL Server can perform standard

operations while your application logic executes through the managed code.

15


Language Support

The Microsoft .NET Platform currently offers built-in support for three languages: C#,

Visual Basic, and JScript.

ADO.NET Overview

ADO.NET is an evolution of the ADO data access model that directly addresses user

requirements for developing scalable applications. It was designed specifically for the web

with scalability, statelessness, and XML in mind.

ADO.NET uses some ADO objects, such as the Connection and Command objects, and also

introduces new objects. Key new ADO.NET objects include the DataSet, DataReader, and

DataAdapter.

When dealing with connections to a database, there are two different options: SQL

Server .NET Data Provider (System.Data.SqlClient) and OLE DB .NET Data Provider

(System.Data.OleDb). In these samples we will use the SQL Server .NET Data Provider.

These are written to talk directly to Microsoft SQL Server. The OLE DB .NET Data Provider

is used to talk to any OLE DB provider (as it uses OLE DB underneath).

Connections

Connections are used to 'talk to' databases, and are represented by provider-specific

classes such as SQLConnection. Commands travel over connections and resultsets are returned

in the form of streams which can be read by a DataReader object, or pushed into a DataSet

object.

Commands

Commands contain the information that is submitted to a database, and are represented

by provider-specific classes such as SQLCommand. A command can be a stored procedure

call, an UPDATE statement, or a statement that returns results. You can also use input and

output parameters, and return values as part of your command syntax. The example below

shows how to issue an INSERT statement against the Northwind database.

16


DataReaders

The DataReader object is somewhat synonymous with a read-only/forward-only cursor

over data. The DataReader API supports flat as well as hierarchical data. A DataReader object

is returned after executing a command against a database. The format of the returned

DataReader object is different from a recordset. For example, you might use the DataReader to

show the results of a search list in a web page.

DataSets

The DataSet object is similar to the ADO Recordset object, but more powerful, and

with one other important distinction: the DataSet is always disconnected. The DataSet object

represents a cache of data, with database-like structures such as tables, columns, relationships,

and constraints. However, though a DataSet can and does behave much like a database, it is

important to remember that DataSet objects do not interact directly with databases, or other

source data. This allows the developer to work with a programming model that is always

consistent, regardless of where the source data resides. Data coming from a database, an XML

file, from code, or user input can all be placed into DataSet objects. Then, as changes are made

to the DataSet they can be tracked and verified before updating the source data. The

GetChanges method of the DataSet object actually creates a second DatSet that contains only

the changes to the data. This DataSet is then used by a DataAdapter (or other objects) to

update the original data source.

DataAdapters (OLEDB/SQL)

The DataAdapter object works as a bridge between the DataSet and the source data.

Using the provider-specific SqlDataAdapter (along with its associated SqlCommand and

SqlConnection) can increase overall performance when working with a Microsoft SQL Server

databases. For other OLE DB-supported databases, you would use the OleDbDataAdapter

object and its associated OleDbCommand and OleDbConnection objects.

The DataAdapter object uses commands to update the data source after changes have

been made to the DataSet. Using the Fill method of the DataAdapter calls the SELECT

17


command; using the Update method calls the INSERT, UPDATE or DELETE command for

each changed row. You can explicitly set these commands in order to control the statements

used at runtime to resolve changes, including the use of stored procedures. For ad-hoc

scenarios, a CommandBuilder object can generate these at run-time based upon a select

statement. However, this run-time generation requires an extra round-trip to the server in order

to gather required metadata, so explicitly providing the INSERT, UPDATE, and DELETE

commands at design time will result in better run-time performance.

Fig 1.2.2 ADO.NET Architecture

Advantages of ADO.NET

ADO.NET is the next evolution of ADO for the .Net Framework.

18


ADO.NET was created with n-Tier, statelessness and XML in the forefront. Two new objects, the

DataSet and DataAdapter, are provided for these scenarios.

We can execute a command directly against the database in order to do inserts, updates, and

deletes. You don't need to first put data into a dataset in order to insert, update, or delete it.

Also, you can use a Dataset to bind to the data, move through the data, and navigate data

relationships.

Structured Query Language (SQL)

To work with data in a database, author must use a set of commands and statements (language) defined

by the DBMS software. There are several different languages that can be used with relational

databases; the most common is SQL. Both the American National Standards Institute (ANSI) and the

International Standards Organization (ISO) have defined standards for SQL. Most modern DBMS

products support the Entry Level of SQL-92, the latest SQL standard (published in 1992).

5.11 SQL Server Features

Microsoft SQL Server supports a set of features that result in the following benefits:

Ease of installation, deployment, and use

SQL Server includes a set of administrative and development tools that improve

your ability to install, deploy, manage, and use SQL Server across several sites.

Scalability

The same database engine can be used across platforms ranging from laptop

computers running Microsoft Windows® 95/98 to large, multiprocessor servers

running Microsoft Windows NT®, Enterprise Edition.

Data warehousing

SQL Server includes tools for extracting and analyzing summary data for online

analytical processing (OLAP). SQL Server also includes tools for visually

designing databases and analyzing data using English-based questions.

System integration with other server software

SQL Server integrates with e-mail, the Internet, and Windows.

19


20

Documents

3 Introductiond