Microsoft SQL Server 2008 R2 Unleashed- P33 pdf

FIGURE 10.7 Importing a certificate on the client computer using the Certificate Import Connection Encryption With SQL Server 2008, it is easy to set up Secure Sockets Layer SSL encrypte

NOTE

By default, all network protocols except for VIA are enabled on the client during

installation

That’s all there is to installing SNAC!

Redistributing SNAC with Custom Client Applications

If you build an application that relies on SNAC, you need to be aware that it can be

redis-tributed in two ways:

As part of any SQL Server 2008 installation or upgrade

As a custom application installation dependency

When you are building MSI files for an application, it is important that you register

sqlncli.msi as a package dependency (and, of course, to install it as well, if it is not

present on the destination machine) This helps ensure that SNAC will not be accidentally

uninstalled from the destination machine without first flashing a warning to users,

indi-cating that any application that relies on it will break To do this, you execute the

follow-ing command early in your application’s installation process:

msiexec /i sqlncli.msi APPGUID={unique identifier for your product}

NOTE

The program name for SNAC found in the Add or Remove Programs Control Panel

applet is Microsoft SQL Server 2008 Native Client, not SQL Native Client, as it is

com-monly known

Client Configuration

Client configuration is a many-leveled beast, consisting of operating system tasks such as

installing protocols, application tasks such as choosing or coding to a specific Application

Programming Interface (API), provider, or driver, and maintenance tasks such as

configur-ing network settconfigur-ings, buildconfigur-ing connection strconfigur-ings, and so on The followconfigur-ing sections cover

a broad range of these tasks, focusing on the most common Many examples utilize

TCP/IP both because it is the default protocol for remote clients and because it is the most

widely used

No chapter can cover all the possible ways of connecting, but this one is designed to give

you the tools you need to get set up right from the start and to navigate your way in case

specific issues arise

Client Configuration Using SSCM

The Client Network Utility available prior to SQL Server 2005 has been decommissioned,

and all its functionality is now built into SSCM This includes the capability to create

server aliases, to enable and prioritize network protocols, to control the various SQL Server

services, and more

NOTE

One thing Microsoft is keen on including in Books Online is that neither Setup nor

sqlncli.msi installs the actual network protocols themselves, nor do they enable

them at the operating system level This means that if you do not have TCP/IP

installed and you need to start using it, you have to first set it up by using the Network

Connections Control Panel applet (if you’re using Windows, that is)

You can launch SSCM directly from its Start menu icon, or you can access it in the

Services and Applications node of the Computer Management console When you

have SSCM up and running, to access its client-side functionality, you expand its top-level

node (SQL Server Configuration Manager (servername)) and then you click the SQL

Native Client 10.0 Configuration node Below it, you click the Client Protocols node

to reveal the enabled state and priority order of each protocol, in grid format, in the right

pane (see Figure 10.4)

From this screen, you can right-click any of the protocols to change their enabled state,

view Properties pages, or change the default connection order (except that of shared

memory, which is always tried first and whose order cannot be changed) The following is

the default connection order for clients connecting without the benefit of a server alias,

connection string, or other means:

FIGURE 10.4 SSCM’s Client Protocols screen

FIGURE 10.5 The TCP/IP Properties screen

Shared memory

TCP/IP

Named pipes

(As the grid shows, VIA is disabled by default.) When you are connecting remotely, TCP/IP

is the first protocol attempted because shared memory is local only

NOTE

When a client does not specify a connection protocol, SNAC automatically tries each

protocol in the list in sequence, according to the Order column The first protocol to

connect successfully wins

If the winning connection is subsequently rejected by the server for any reason, no

other protocols are tried

Note also that local clients using MDAC 2.8 or lower cannot connect using shared

memory, and they are automatically switched to named pipes if they attempt to do so

Let’s examine one of the protocols To start, you need to double-click TCP/IP under the

Name column to open the TCP/IP Properties screen (see Figure 10.5)

The values stored here are used by TCP/IP clients as default connection values, and they are

applied only when a specific server alias or other configuration mechanism is not in use

They are also used by the SQL Server 2008 client tools when shared memory is not available

FIGURE 10.6 Alias properties for a new named pipe server alias

As you can see, the default port, 1433, is set up to connect to the more commonly

config-ured default instances of SQL Server By editing the values on this page, you can change

the default port number, enabled state, keep-alive values, and other settings (when

editing other protocols) You should edit and enable the protocols according to your

specific needs

Server Aliases

A server alias is a name that is used like a server name that represents a group of server

settings for use by connecting clients Server aliases are very handy because of the way

they simplify connection parameters: clients need only specify the alias name, and SNAC

pulls the rest of the information (such as the IP address, TCP port number, and pipe

name) from SSCM at connection time

To create a server alias, you right-click the Aliases node under SQL Native Client

Configuration and choose New Alias On the Alias - New screen that appears (see Figure

10.6), you specify the alias name, protocol (except shared memory, for which you cannot

create an alias), and server name (local , , and localhost also work for local connections

over TCP/IP or named pipes.)

When you make your protocol selection, the grid rows change to dynamically reveal the

settings particular to that protocol When you are finished, you click OK, and your alias is

ready for use

FIGURE 10.7 Importing a certificate on the client computer using the Certificate Import

Connection Encryption

With SQL Server 2008, it is easy to set up Secure Sockets Layer (SSL) encrypted

client/server communication over all protocols The SNAC net-library handles the tasks of

encryption and decryption on both the server and client ends (Note that this process

does cause a slight decrease in performance.) Setting it up requires both server-side and

client-side configuration changes; this section covers only the client-side changes in detail

SQL Server 2008 enables encryption using two types of certificates:

Certificates generated by and obtained from an external certification authority such

as VeriSign

Certificates generated by SQL Server 2008 (known as self-signed certificates)

The bit strength of the encryption (40-bit or 128-bit) depends on the bit strength of the

operating systems of the computers involved in the connection

To set up the server for encryption, your administrator registers a certificate on the server

operating system (using the Certificates Management console) and then installs it in the

Database Engine

If an externally signed certificate is not installed on the server, SQL Server uses its built-in

self-signed certificate (A server administrator may also create and save a self-signed

certifi-cate by using SQL Server 2008 via the new CREATE CERTIFICATE and BACKUP CERTIFICATE

T-SQL syntax.) It is also up to the server to decide whether encryption is required or

optional for connecting clients

The client’s half of the job is to have installed what is known as a root-level certificate that

is issued by the same certification authority as the server’s certificate To install a root-level

certificate, you right-click the certificate itself (a cer or crt file) and select Install

Certificate to launch the Certificate Import Wizard You click Next on the welcome screen

to reach the Certificate Store screen (see Figure 10.7) Then you select the first radio button

(Automatically Select the Certificate Store) and then click Next Finally, you click Finish

FIGURE 10.8 Forcing clients to request an encrypted connection using SSCM

Next, you launch SSCM, right-click the SQL Native Client 10.0 Configuration node,

and then select Properties The Flags tab appears (see Figure 10.8) in the Properties window

You set the Force Protocol Encryption property value to Yes This causes clients to

request an SSL-encrypted connection when communicating with the Database Engine If

the server does not respond in kind, the connection is killed

The Trust Server Certificate property gives clients a choice in how they deal with

server certificates:

To use a self-signed certificate, you set the property value to Yes This option

prevents SNAC from validating the server’s certificate

To use an externally signed certificate, you set the property value to No, which causes

SNAC to validate the server’s certificate

SSMS can also connect over an encrypted connection When connecting using the

Connect to Server dialog, you click the Options button and then click the Connection

Properties tab Then you choose your database and protocol and, at the bottom left, check

the Encrypt Connection check box

Client Data Access Technologies

The question of which data access technology to use with SQL Server 2008 is a common

one, with a seemingly easy answer: you use SNAC because it has all the latest and greatest

functionality, all rolled into one (You learn how to use SNAC in the sections that follow.)

A more correct answer is that your choice depends on which software technologies your

clients currently use and what their specific needs are

Your data access options consist of providers and drivers, whose functionality is often

encapsulated inside code libraries known as net-libraries (such as SNAC’s sqlncli10.dll)

In addition to these net-libraries, supporting services such as MDAC’s OLE DB Core

Services are also available, providing useful functionality not found in the net-libraries,

such as connection pooling (ADO.NET also functions as a service, to a certain degree.)

NOTE

The Microsoft Data Access Components (MDAC) has a new name that started with the

Vista operating system The data access components are now called Windows Data

Access Components or Windows DAC or WDAC References to MDAC in this chapter

also apply to the Windows DAC

Provider Choices

A provider is software used for accessing various data stores in a consistent manner

conforming to a specification, such as OLE DB A provider may contain an API Clients

that use providers are known as consumers SMSS and SQLCMD, for example, are

consumers of the SNAC OLE DB provider

You can choose from the following providers:

built into SNAC; it is also known as SQLNCLI COM applications might want to

switch to this provider to access the latest functionality; doing so also provides

access to SQL Server 7 and 2000 databases

the System.Data.SqlClient namespace in the NET Framework Managed code

applications should use it to access the latest SQL Server 2008 functionality from

.NET 3.5 applications .NET 1.0, 1.1, and 2.0 applications do not have access to all

the latest SQL Server 2008 functionality through this provider

SQLOLEDB, is specialized for accessing SQL Server data and is distributed with MDAC

COM applications may continue to use it to access SQL Server 2008, or they can

switch to SQLNCLI for the latest functionality

as MSDASQL, is distributed with MDAC ADO applications can continue to use it to

access SQL Server 2008, but SQL Server does not support the latest SNAC-specific

OLE DB functionality

Microsoft has also made available a few implementation-specific OLE DB providers, such

as the OLE DB provider for DB2, a COM component for integrating IBM DB2 and SQL

Server 2008 data

Driver Choices

A driver in this context can be defined as software that conforms to a standard such as

Open Database Connectivity (ODBC) and provides an API for accessing a specific type of

data store osql.exe is a good example of an application that uses an ODBC driver (the

SNAC driver)

These are the available drivers:

into SNAC COM applications might want to switch to this driver to access the latest

functionality

MDAC for accessing SQL Server databases COM applications can continue to use it

to access SQL Server 2008, or they can switch to the SNAC ODBC driver for the

latest functionality This driver also provides access to SQL Server 7, 2000, and 2005

databases

specifically for accessing SQL Server data from Java code

CAUTION

Although it is still possible to connect to SQL Server 2008 by using DB-library and

Embedded SQL, Microsoft has deprecated them both, and they will not be supported in

future editions

Connecting Using the Various Providers and Drivers

Now that you know what your options are in terms of providers and drivers, the following

sections detail them one by one, with a special focus on putting the features in SQL Server

2008 to work

Using SNAC

SNAC is a net-library that contains both the latest OLE DB provider and ODBC driver for

using the rich features in SQL Server 2008 databases It is compatible for accessing SQL

Server 7, 2000, and 2005 databases as well

The code for SNAC is contained in the single dynamic link library sqlncli10.dll, and it

serves as provider, driver, and API for applications that call its underlying COM functions

from unmanaged code (that is, from C or C++)

The bottom line with SNAC is that if you’re building applications that need to exploit the

latest features of SQL Server 2008, you need to use its APIs If you don’t, your application

will continue to work without SNAC, but those new features will not be available

NOTE

A large number of connection keywords are available for use with SNAC connections A

few of them are illustrated in the examples that follow, but for a complete reference,

see the Books Online topic “Using Connection String Keywords with SQL Native Client.”

Using OLE DB with SNAC Applications that call the COM APIs for OLE DB need to have

the connection provider value changed from SQLOLEDB to SQLNCLI10 You also need to use

the SNAC header file, as in the following example:

include “sqlncli.h”;

sqlncli.h contains the latest function prototypes and other definitions for use with

SNAC This file is named the same as it was in SQL Server 2005, but it is installed in a

different location

NOTE

The SNAC OLE DB provider is OLE DB version 2.0 compliant

Using ODBC with SNAC To connect to SQL Server 2008 using ODBC, you use a

connec-tion string or a DSN that is accessible to the client applicaconnec-tion at runtime The ODBC

driver used with SQL Server 2000 (simply called SQL Server) can still be used but is not

the best option for SQL Server 2005 or 2008 To get the latest SNAC functionality, you

must use the driver called SQL Native Client 10.0 (for example, DRIVER={SQL Native

Client 10.0})

To create a SNAC ODBC DSN, you run the Data Sources (ODBC) applet found in your

operating system’s administrative tools You create a system, file, or user DSN, and you

need to be sure to select the SQL Server Native Client 10.0 driver on the Create New Data

Source screen that appears On this screen, you click the Advanced button to enter any

SNAC-specific connection string keyword-value pairs, as shown in Figure 10.9

You finish the wizard by entering the configuration data as you normally would, and you

can use you new DSN just as you would any other For more information on building

COM applications that utilize SNAC, see the Books Online topic “Creating a SQL Native

Client ODBC Driver Application.”

Using ADO with SNAC Of course, the first recommendation is that if you’re still using

ADO, you should switch to ADO.NET if you can If that isn’t feasible, you can still access

SQL Server 2008 from your ADO applications But you should do so only if you need the

new features; in this case, you need to start using the SNAC OLE DB provider in your code

To do so, you first install SNAC, and then you update your connection strings (or DSNs) to

use the new SQLNCLI value for the Provider connection string keyword Then you set the

DataTypeCompatibility keyword to 80 Here’s an example (in Visual Basic 6 code):

Dim MyConnection As New ADODB.Connection

Dim MyFirstOpenRecordset As New ADODB.Recordset

Dim MySecondOpenRecordset As New ADODB.Recordset

Dim ConnString As String

Dim SelectResultsCount As Integer

Connstring =

“Provider=SQLNCLI; DataTypeCompatibility=80; Database=MyAppsDB;” & _

“Server=.\SQLEXPRESS; AttachDBFileName=c:\MyDBs\MyAppsDB.mdf;” & _

“MARS Connection=true; Integrated Security=SSPI;”

MyConnection.ConnectionString = ConnString

MyConnection.Open

‘ Using 2 open recordsets on one connection puts MARS to work:

Set MyFirstOpenRecordset =

MyConnection.Execute(

“SELECT TOP 10 * FROM MyTable”,

SelectResultsCount,

adCmdText

)

Set MySecondOpenRecordset =

MyConnection.Execute(“SELECT TOP 10 * FROM MySecondTable”, _

SelectResultsCount, adCmdText)

‘ and so on

Note the use of the AttachDBFileName connection string keyword, which instructs SQL

Server 2008 to attach the specified Microsoft data file (MyAppsDB.mdf)

Using the NET Framework Data Provider for SQL Server

.NET applications that use the System.Data.SqlClient namespace rely on the NET

Framework data provider and ADO.NET To use this provider, you simply add the

follow-ing statement to your C# code file:

using System.Data.SqlClient;