... DataLinkLayer Protocols- The Frame
31
• Remember that although there are many different DataLinklayerprotocols that describe
Data Linklayer frames, each frame ... logical signal paths are defined by DataLinklayer
protocols.
• The DataLinklayer "sees" the logical topology of a network when
24
• The DataLinklayer "sees" the logical ... chapter, you will be able to:
• Explain the role of DataLinklayerprotocols in data transmission.
• Describe how the DataLinklayer prepares data for transmission on
network media.
• Describe...
...
+ HF – (thoại tương tự)
+ VHF Data link: VDL Mode2 – (dữ liệu), VDL mode3 - (thoại và dữ liệu), và
VDL mode4 - (dữ liệu).
+ SSR Mode S - (dữ liệu)
+ HF Datalink – (dữ liệu).
Các dịch vụ thông ... trên vùng lãnh thổ Việt Nam.
Luận văn “ ỨNG DỤNG CỦA VHF DATALINK MODE 4 TRONG MÔI TRƯỜNG CNS/
ATM ” nghiên cứu công nghệ kỹ thuật VHF DataLink Mode 4, một liên kết dữ liệu số
sử dụng sóng VHF ... phân lớp điều khiển truy nhập MAC ( Medium
Access Control ), Dịch vụ liên kết dữ liệu DLS ( DataLink service ) và thực thể quản lý
liên kết ( LME ). Lớp liên kết dữ liệu VDL cung cấp sự truyền...
...
CHAPTER 8 ■ DATA ACCESS LAYER
174
private void DisconnectFromDatabase()
{
if (_databaseConnection.State != ConnectionState.Open)
{
_databaseConnection.Close();
}
}
private IDataReader ... CreateUserFromReader(IDataReader dataReader)
{
int id = dataReader.GetInt32(0);
string name = dataReader.GetString(1);
string emailAddress = dataReader.GetString(2);
string password = dataReader.GetString(2); ... the project, only the parts of the database that are in use by the object model should have
been generated.
CHAPTER 8 ■ DATA ACCESS LAYER
164
DATABASE KEYS
Database tables should always have...
... modules that focus on the data access layer
(DAL). In Module 8, “The Nontransactional Data Access Layer, ” you learned
about data retrieval. In this module, you will learn about data manipulation. ... same data
access technologies as that of the nontransactional DAL. The following data
access technologies were covered in Module 8, “The Nontransactional Data
Access Layer :
!
Microsoft Data ...
DAL: Module 8, “The Nontransactional Data Access Layer and Module 9,
“The Transactional Data Access Layer. ” The DAL is an application’s means of
access to data services.
After completing this...
... Nontransactional Data Access Layer 15
Data Shaping Service
!
Relation-based Hierarchical Rowsets
!
Group-based Hierarchies
!
Using Data Shaping
!
Sample Definition
OLE DB provides a Data Shaping ... is any component that owns data. It exposes its data in a
tabular format, regardless of the format in which it stores data. Examples of
data providers are relational database management systems ... Nontransactional Data Access Layer
#
##
#
Introduction to the Data Access Layer
!
The Business Problem
!
Splitting the DAL
The DAL buffers the entire system from the underlying data services....
... trường hợp về sự cố mạng có thể do phần cứng hay phần mềm:
Phần cứng (Lớp Physical, Data Link) : Đèn liên kết (Link ) của card mạng không
sáng
Kiểm tra đầu nối card mạng và đầu cáp nối trên HUB/SWITCH
...
... same data
access technologies as that of the nontransactional DAL. The following data
access technologies were covered in Module 8, “The Nontransactional Data
Access Layer :
!
Microsoft Data ... DAL.
Module 9: The Transactional Data Access Layer 3
The Business Problem
DAL
Connected Business
Logic Layer
Disconnected Business
Logic Layer
Facade Layer
Web Services Facade Business ... data services layer. The transactional DAL can return to the
business logic layer either success or failure. If the transaction also involved
retrieving data as a result of updates to the data, ...
...
Recipe 1.13 Using the DataLink Properties Dialog Box
Problem
You want to display the DataLink Properties dialog
b
ox from an application so that users
can create their own database connections ... Reference
Dialog.
The sample code contains a single event handler:
Data Link Dialog Button.Click
Creates and displays a DataLink Properties dialog box using the Microsoft OLE
DB Service Component ... shown in Example 1-10
.
Example 1-10. File: DataLinkDialogForm.cs
// Namespaces, variables, and constants
using System;
// . . .
private void dataLinkDialogButton_Click(object sender, System.EventArgs...
... DLC Protocols
(LAPB,LAPD)
Link Access Procedure, Balanced (LAPB)
Part of X.25 (ITU-T)
Subset of HDLC - ABM
Point to point link between system and packet
switching network node
Link ...
i
Transmitter goes back to frame
i
and
retransmits
William Stallings
Data and Computer
Communications
Chapter 7
Data Link Control
Cyclic Redundancy Check
For a block of
k
bits transmitter ... frames
Three phases
Initialization
Data transfer
Disconnect
Control Field
Different for different frame type
Information - data to be transmitted to user (next
layer up)
Flow and error control...
... serves
as both ACK 2 and ACK 3.
11.2
11-1 FRAMING
11-1 FRAMING
The datalinklayer needs to pack bits into
The datalinklayer needs to pack bits into
frames
frames
, so
, so
that each frame ... sender events. Request events are
triggered by data from the network layer; arrival events
are triggered by acknowledgments from the physical
layer. There is no time-out event here because ... of protocols discussed in this chapter
11.21
Algorithm 11.3 Sender-site algorithm for Stop-and-Wait Protocol
11.10
Flow control refers to a set of procedures
used to restrict the amount of data
that...
... performance
using striping techniques at the link- layer, transport -layer, and application -layer. We are
the first to implement and evaluate a transport -layer protocol that can utilize multiple
paths ... inverse-
multiplexing in link- layerprotocols to enhance throughput by aggregating the bandwidth
of different links. Adiseshu et al [1], Duncanson et al [23], and Snoeren [81] provided
link- striping algorithms ... and robustness.
Based on the network layer where the striping techniques are applied, we classify them
into link- layer, transport -layer, and application -layer striping.
2.1 Network Testbeds
We...
... LayerProtocols
• The Application layer uses protocols that are implemented within
applications and services.
• While applications provide people a way to create messages and
application layer ... upper OSI model layers
provide network services to end user applications.
• Describe how the TCP/IP Application Layerprotocols provide the
services specified by the upper layers of the OSI ... www.bkacad.com
OSI and TCP/IP Model
• The Presentation layer has three primary functions:
1. Coding and conversion of Application layerdata to ensure that
data from the source device can be interpreted...
... proper data model for PACE-Ling
(Sec. 2.2). The ultimate goal of our research is to
create a modular extensible data model for multi-
layer annotated corpora. To achieve this, we aim
to create a data ... exists.
2 Data models
There are three purposes data models can serve.
The first purpose is context suitability. A data
model used for this purpose must reflect as well
as possible the data the user ... texts. Due to
the vast amount of data involved in the project, the
data model is not mapped to XML files, but to a
SQL database for a better query performance.
The DDD data model can be seen as an...