在本次实验中，你将会和一个银行的程序打交道。通过这个程序，你将会看到如何加入transaction。首先你需要创建一个数据库。打开Transactions文件夹，使用Bank.sql脚本创建数据库。
打开Bank.sln解决方案。想往常一样，解决方案中包含了服务端和客户端的程序。我们先来看服务端。服务端包含了AccountService和AccountManger两个服务。AccountService实现了IAccount接口，用于完成借贷功能：
[ServiceContract]
interfaceIAccount
{
[OperationContract] void Credit(int accountNumber,decimal amount); [OperationContract] void Debit(int accountNumber,decimal amount);
}[ServiceBehavior(InstanceContextMode =
InstanceContextMode.PerCall)]
classAccountService : IAccount
{
public void Credit(int accountNumber,decimal amount)
{ BankAccountsTableAdapter adapter = new BankAccountsTableAdapter(); BankDataSet.BankAccountsDataTable accounts = adapter.GetData(); BankDataSet.BankAccountsRow account = accounts.FindByNumber(accountNumber); account.Balance += amount; adapter.Update(accounts);
} public void Debit(int accountNumber,decimal amount) { BankAccountsTableAdapter adapter = new BankAccountsTableAdapter(); BankDataSet.BankAccountsDataTable accounts = adapter.GetData(); BankDataSet.BankAccountsRow account = accounts.FindByNumber(accountNumber); if(account.Balance >= amount) { account.Balance -= amount; } else { throw new InvalidOperationException(“Debit amount is greater than balance in account #“ + accountNumber); } adapter.Update(accounts); }}
代码不是很复杂，这里就不讲解了。
配置文件对AccountService暴露了两个endpoint，一个使用TCP、一个使用HTTP：
<service name = “AccountService”><
endpoint
address = “net.tcp://localhost:8001/AccountService/” binding = “netTcpBinding”
contract = “IAccount”
/>
<
endpoint
address = “http://localhost:8002/AccountService” binding = “wsHttpBinding”
contract = “IAccount”
/>
</service>
AccountManger类实现了IAccountManger接口，用来查询帐户：
[DataContract]
classAccount
{
[DataMember] public string Name; [DataMember] public decimal Balance; [DataMember] public int Number;}[ServiceContract]interface
IAccountManager
{
[OperationContract] Account[] GetAccounts();}
我们再来看客户端。客户端使用了一个winform程序来模拟银行的操作：
点击Transfer按钮将会做转帐的操作。在代码上，client端会对第一个帐户创建一个TCP代理类来完成贷款动作。接下来会对第二个帐户创建一个HTTP代理类来完成借款动作。完成转帐动作后会重新获取帐户信息显示到grid中。
using(AccountClient account1 = new AccountClient(“TCP“))
using(AccountClient account2 = new AccountClient(“HTTP“))
{
account1.Credit(destinationAccount,amount); account2.Debit(sourceAccount,amount);}
目前client端没有任何事务控制，也没有错误处理。程序的架构如下图所示：
在没有事务控制的情况下，如果帐户号码是正确的，那么不会出现任何问题。比如我们将100元从帐户123转到456。但是如果帐户输入错误了，那么就会有问题了。比如我们将100元从帐户777转到456。点击Transfer后我们会收到异常（因为程序没有错误处理），不用管这个错误，刷新grid后我们会发现456帐户上多了100元！
接下来我们就加入事务控制吧。
加入事务
为AccountService加入operation behavior：
classAccountService : IAccount
{
[OperationBehavior(TransactionScopeRequired = true)] public void Credit(int accountNumber, decimal amount) {……} [OperationBehavior(TransactionScopeRequired = true)] public void Debit(int accountNumber, decimal amount) {……}}
为了让事务能传播到服务端，我们需要在服务端加上TransactionFlow的属性。同样也需要在client端的contract定义上加入相同的属性：
[ServiceContract]
interfaceIAccount
{
[OperationContract] [TransactionFlow(TransactionFlowOption.Allowed)] void Credit(int accountNumber, decimal amount); [OperationContract] [TransactionFlow(TransactionFlowOption.Allowed)] void Debit(int accountNumber, decimal amount);}
同时还需要在配置文件中对bingding加入允许事务的属性，服务端：
<services> <service name = “AccountService”>
<
endpoint
address = “net.tcp://localhost:8001/AccountService/” binding = “netTcpBinding”
contract = “IAccount”
bindingConfiguration=”TransactionalTCP”
/>
<
endpoint
address = “http://localhost:8002/AccountService” binding = “wsHttpBinding”
contract = “IAccount”
bindingConfiguration=”TransactionalHTTP”
/>
</service>
……</services>
<bindings>
<netTcpBinding>
<binding name=”TransactionalTCP” transactionFlow=”true” />
</netTcpBinding>
<wsHttpBinding>
<binding name=”TransactionalHTTP” transactionFlow=”true” />
</wsHttpBinding>
</bindings>
客户端：
<client> <endpoint name = “TCP”
address = “net.tcp://localhost:8001/AccountService/”
binding = “netTcpBinding”
contract = “IAccount”
bindingConfiguration=”TransactionalTCP”
/>
<endpoint name = “HTTP”
address = “http://localhost:8002/AccountService/”
binding = “wsHttpBinding”
contract = “IAccount”
bindingConfiguration=”TransactionalHTTP”
/>
……</client>
<bindings>
<netTcpBinding>
<binding name=”TransactionalTCP” transactionFlow=”true” />
</netTcpBinding>
<wsHttpBinding>
<binding name=”TransactionalHTTP” transactionFlow=”true” />
</wsHttpBinding>
</bindings>
对client项目添加对System.Transactions.dll的引用。打开BankClientForm.cs文件，添加using语句：using System.Transactions。
下面，我们将在client端使用transaction scope将它调用的两个服务包到一个事务中：
使用TrasactionScope来包住两个调用：
using(TransactionScope scope = newTransactionScope())
using (AccountClient account1 = new AccountClient(“TCP“))
using (AccountClient account2 = new AccountClient(“HTTP“))
{
account1.Credit(destinationAccount, amount); account2.Debit(sourceAccount, amount); scope.Complete();}
重复我们一开始的实验，你会发现帐户不正确时所有操作都会进行回滚。
转载于:https://www.cnblogs.com/yunkunyang/archive/2008/04/11/1148703.html
发布者：全栈程序员-站长，转载请注明出处：https://javaforall.net/111032.html原文链接：https://javaforall.net
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