ch08.htm

corba比较入门级的介绍详细间接了corba访问发布各种细节。

<TT> 37: </TT>
<TT> 38: // Destructor.</TT>
<TT> 39: ATMCardImpl::~ATMCardImpl() {</TT>
<TT> 40: </TT>
<TT> 41: }</TT>
<TT> 42: </TT>
<TT> 43: CORBA::Short ATMCardImpl::pin() {</TT>
<TT> 44: </TT>
<TT> 45:     return myPIN;</TT>
<TT> 46: }</TT>
<TT> 47: </TT>
<TT> 48: void ATMCardImpl::pin(CORBA::Short val) {</TT>
<TT> 49: </TT>
<TT> 50:     myPIN = val;</TT>
<TT> 51: }</TT>
<TT> 52: </TT>
<TT> 53: CORBA::Boolean ATMCardImpl::isAuthorized(Account_ptr account) {</TT>
<TT> 54: </TT>
<TT> 55:     std::vector&lt;Account_ptr&gt;::iterator first = myAccounts.begin();</TT>
<TT> 56:     std::vector&lt;Account_ptr&gt;::iterator last = myAccounts.end();</TT>
<TT> 57:     IsAccountEqual predicate(account);</TT>
<TT> 58: </TT>
<TT> 59:     std::vector&lt;Account_ptr&gt;::iterator matchedAccount = std::</TT>
<TT> 60:             find_if(first, last, predicate);</TT>
<TT> 61:     if (matchedAccount == last) {</TT>
<TT> 62: </TT>
<TT> 63:         // Account not found; return false.</TT>
<TT> 64:         return 0;</TT>
<TT> 65:     } else {</TT>
<TT> 66: </TT>
<TT> 67:         // Account found; return true.</TT>
<TT> 68:         return 1;</TT>
<TT> 69:     }</TT>
<TT> 70: }</TT>
<TT> 71: </TT>
<TT> 72: void ATMCardImpl::removeAccount(Account_ptr account) throw</TT>
<TT> 73:         (InvalidAccountException) {</TT>
<TT> 74: </TT>
<TT> 75:     if (!isAuthorized(account)) {</TT>
<TT> 76: </TT>
<TT> 77:         // Invalid Account; throw an exception.</TT>
<TT> 78:         throw InvalidAccountException();</TT>
<TT> 79:     }</TT>
<TT> 80: </TT>
<TT> 81:     // Delete the given Account.</TT>
<TT> 82:     myAccounts.erase(&amp;account);</TT>
<TT> 83:     account-&gt;_release();</TT>
<TT> 84: }</TT>
<TT> 85: </TT>
<TT> 86: void ATMCardImpl::addAccount(Account_ptr account) throw</TT>
<TT> 87:         (InvalidAccountException) {</TT>
<TT> 88: </TT>
<TT> 89:     if (isAuthorized(account)) {</TT>
<TT> 90: </TT>
<TT> 91:         // Account has already been added, so throw an exception.</TT>
<TT> 92:         throw InvalidAccountException();</TT>
<TT> 93:     }</TT>
<TT> 94: </TT>
<TT> 95:     // Add the created Account at the end of the list.</TT>
<TT> 96:     myAccounts.push_back(Account::_duplicate(account));</TT>
<TT> 97: }</TT>
<TT> 98: </TT>
<TT> 99: AccountList* ATMCardImpl::getAccounts() {</TT>
<TT>100: </TT>
<TT>101:     AccountList* list = new AccountList(myAccounts.size());</TT>
<TT>102:     CORBA::Long i;</TT>
<TT>103: </TT>
<TT>104:     for (i = 0; i &lt; myAccounts.size(); i++) {</TT>
<TT>105:         (*list)[i] = Account::_duplicate(myAccounts[i]);</TT>
<TT>106:     }</TT>
<TT>107: </TT>
<TT>108:     return list;
109: }</TT> </FONT></PRE>
<P>Because nothing different needs to be done when a <TT>BankImpl</TT> object is
created, no changes are necessary from the original <TT>BankMain.cpp</TT>, but, for
good measure, it appears in Listing 8.12.
<H4><FONT COLOR="#000077">Listing 8.12. BankMain.cpp.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // BankMain.cpp</TT>
<TT> 2: </TT>
<TT> 3: #include &quot;BankImpl.h&quot;</TT>
<TT> 4: </TT>
<TT> 5: #include &lt;iostream.h&gt;</TT>
<TT> 6: </TT>
<TT> 7: #include &quot;../BankServer_c.h&quot;</TT>
<TT> 8: </TT>
<TT> 9: CORBA::BOA_var boa;</TT>
<TT>10: </TT>
<TT>11: int main(int argc, char *const *argv) {</TT>
<TT>12: </TT>
<TT>13:     // Check the number of arguments; there should be exactly one</TT>
<TT>14:     // (two counting the executable name itself).</TT>
<TT>15:     if (argc != 2) {</TT>
<TT>16:         cout &lt;&lt; &quot;Usage: Bank &lt;bankname&gt;&quot; &lt;&lt; endl;</TT>
<TT>17:         return 1;</TT>
<TT>18:     }</TT>
<TT>19: </TT>
<TT>20:     // Assign the bank name to the first argument.</TT>
<TT>21:     const char* bankName = argv[1];</TT>
<TT>22: </TT>
<TT>23:     // Initialize the ORB and BOA.</TT>
<TT>24:     CORBA::ORB_var orb = CORBA::ORB_init(argc, argv);</TT>
<TT>25:     ::boa = orb-&gt;BOA_init(argc, argv);</TT>
<TT>26: </TT>
<TT>27:     // Create a Bank object.</TT>
<TT>28:     BankImpl bank(bankName);</TT>
<TT>29: </TT>
<TT>30:     // Notify the BOA that the BankImpl object is ready.</TT>
<TT>31:     ::boa-&gt;obj_is_ready(&amp;bank);</TT>
<TT>32: </TT>
<TT>33:     // Locate a BankServer object and register with it.</TT>
<TT>34:     BankServer_var bankServer;</TT>
<TT>35:         try {</TT>
<TT>36:             bankServer = BankServer::_bind();</TT>
<TT>37:     } catch (const CORBA::Exception&amp; ex) {</TT>
<TT>38: </TT>
<TT>39:         // The bind attempt failed...</TT>
<TT>40:         cout &lt;&lt; &quot;BankImpl: Unable to bind to a BankServer.&quot; &lt;&lt; endl;</TT>
<TT>41:         cout &lt;&lt; ex &lt;&lt; endl;</TT>
<TT>42:         return 1;</TT>
<TT>43:     }</TT>
<TT>44:     try {</TT>
<TT>45:         bankServer-&gt;registerBank(&amp;bank);</TT>
<TT>46:     } catch (const CORBA::Exception&amp; ex) {</TT>
<TT>47: </TT>
<TT>48:         // The registerBank() attempt failed...</TT>
<TT>49:         cout &lt;&lt; &quot;BankImpl: Unable to register Bank.&quot; &lt;&lt; endl;</TT>
<TT>50:         cout &lt;&lt; ex &lt;&lt; endl;</TT>
<TT>51:         return 1;</TT>
<TT>52:     }</TT>
<TT>53: </TT>
<TT>54:     // Wait for CORBA events.</TT>
<TT>55:     cout &lt;&lt; &quot;Bank \&quot;&quot; &lt;&lt; bankName &lt;&lt; &quot;\&quot; ready.&quot; &lt;&lt; endl;</TT>
<TT>56:     ::boa-&gt;impl_is_ready();</TT>
<TT>57: </TT>
<TT>58:     // When this point is reached, the application is finished.</TT>
<TT>59:     return 0;
60: }</TT></FONT></PRE>
<H3><A NAME="Heading10"></A><FONT COLOR="#000077">Implementing the ATM Server</FONT></H3>
<P>The implementation of <TT>ATMImpl</TT> (see Listings 8.13 and 8.14) is clear-cut.
The <TT>ATMImpl</TT> simply forwards requests to withdraw funds into an <TT>Account</TT>,
to deposit funds into an <TT>Account</TT>, and to get the current balance of an <TT>Account</TT>.
Each operation uses the <TT>ATMCard</TT> to authorize the transaction, and if the
<TT>ATMCard</TT> approves, the transaction is forwarded to the <TT>Account</TT>.
Because the transaction itself is performed by the <TT>Account</TT>, the implementations
for <TT>withdraw()</TT>, <TT>deposit()</TT>, and <TT>getBalance()</TT> are simple.
<H4><FONT COLOR="#000077">Listing 8.13. ATMImpl.h.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // ATMImpl.h</TT>
<TT> 2: </TT>
<TT> 3: #ifndef ATMImpl_h</TT>
<TT> 4: #define ATMImpl_h</TT>
<TT> 5: </TT>
<TT> 6: #include &quot;../ATM_s.h&quot;</TT>
<TT> 7: </TT>
<TT> 8: class ATMImpl : public _sk_ATM {</TT>
<TT> 9: </TT>
<TT>10: public:</TT>
<TT>11:     // Constuctor.</TT>
<TT>12:     //</TT>
<TT>13:     // name - the name of this ATM.</TT>
<TT>14:     ATMImpl(const char* name);</TT>
<TT>15: </TT>
<TT>16:     // Destructor.</TT>
<TT>17:     ~ATMImpl();</TT>
<TT>18: </TT>
<TT>19:     // These methods are described in ATM.idl.</TT>
<TT>20:     virtual char* name();</TT>
<TT>21:     virtual void name(const char* val);</TT>
<TT>22:     virtual CORBA::Float withdraw(ATMCard_ptr card, Account_ptr</TT>
<TT>23:             account, CORBA::Short pin, CORBA::Float amount) throw</TT>
<TT>24:             (AuthorizationException, InvalidAmountException,</TT>
<TT>25:             InsufficientFundsException);</TT>
<TT>26:     virtual CORBA::Float deposit(ATMCard_ptr card, Account_ptr</TT>
<TT>27:             account, CORBA::Short pin, CORBA::Float amount) throw</TT>
<TT>28:             (AuthorizationException, InvalidAmountException);</TT>
<TT>29:     virtual CORBA::Float getBalance(ATMCard_ptr card, Account_ptr</TT>
<TT>30:             account, CORBA::Short pin) throw</TT>
<TT>31:             (AuthorizationException);</TT>
<TT>32: </TT>
<TT>33: private:</TT>
<TT>34: </TT>
<TT>35:     // Default constuctor.</TT>
<TT>36:     ATMImpl();</TT>
<TT>37: </TT>
<TT>38:     // This ATM's name.</TT>
<TT>39:     char* myName;</TT>
<TT>40: };</TT>
<TT>41: 
42: #endif</TT></FONT></PRE>
<H4><FONT COLOR="#000077">Listing 8.14. ATMImpl.cpp.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // ATMImpl.cpp</TT>
<TT> 2: </TT>
<TT> 3: #include &quot;ATMImpl.h&quot;</TT>
<TT> 4: </TT>
<TT> 5: #include &lt;iostream.h&gt;</TT>
<TT> 6: </TT>
<TT> 7: // Constuctor.</TT>
<TT> 8: //</TT>
<TT> 9: // name - the name of this ATM.</TT>
<TT>10: ATMImpl::ATMImpl(const char* name) : _sk_ATM(name),</TT>
<TT>11:         myName(strdup(name)) {</TT>
<TT>12: </TT>
<TT>13: }</TT>
<TT>14: </TT>
<TT>15: // Default constuctor.</TT>
<TT>16: ATMImpl::ATMImpl() : _sk_ATM(&quot;&quot;), myName(NULL) {</TT>
<TT>17: </TT>
<TT>18: }</TT>
<TT>19: </TT>
<TT>20: // Destructor.</TT>
<TT>21: ATMImpl::~ATMImpl() {</TT>
<TT>22: </TT>
<TT>23:     free(myName);</TT>
<TT>24: }</TT>
<TT>25: </TT>
<TT>26: char* ATMImpl::name() {</TT>
<TT>27: </TT>
<TT>28:     return CORBA::strdup(myName);</TT>
<TT>29: }</TT>
<TT>30: </TT>
<TT>31: void ATMImpl::name(const char* val) {</TT>
<TT>32: </TT>
<TT>33:     free(myName);</TT>
<TT>34:     myName = strdup(val);</TT>
<TT>35: }</TT>
<TT>36: </TT>
<TT>37: CORBA::Float ATMImpl::withdraw(ATMCard_ptr card, Account_ptr</TT>
<TT>38:         account, CORBA::Short pin, CORBA::Float amount) throw</TT>
<TT>39:         (AuthorizationException, InvalidAmountException,</TT>
<TT>40:         InsufficientFundsException) {</TT>
<TT>41: </TT>
<TT>42:     cout &lt;&lt; &quot;ATM: Authorizing Account for withdrawal.&quot; &lt;&lt; endl;</TT>
<TT>43:     if (pin != card-&gt;pin() || !card-&gt;isAuthorized(account)) {</TT>
<TT>44: </TT>
<TT>45:         // Incorrect PIN or card not authorized; throw an</TT>
<TT>46:         // exception.</TT>
<TT>47:         cout &lt;&lt; &quot;  Authorization failed.&quot; &lt;&lt; endl;</TT>
<TT>48:         throw AuthorizationException();</TT>
<TT>49:     }</TT>
<TT>50: </TT>
<TT>51:     cout &lt;&lt; &quot;  Authorization succeeded; forwarding withdrawal &quot; &lt;&lt;</TT>
<TT>52:             &quot;request to Account.&quot; &lt;&lt; endl;</TT>
<TT>53:     return account-&gt;withdraw(amount);</TT>
<TT>54: }</TT>
<TT>55: </TT>
<TT>56: CORBA::Float ATMImpl::deposit(ATMCard_ptr card, Account_ptr</TT>
<TT>57:         account, CORBA::Short pin, CORBA::Float amount) throw</TT>
<TT>58:         (AuthorizationException, InvalidAmountException) {</TT>
<TT>59: </TT>
<TT>60:     cout &lt;&lt; &quot;ATM: Authorizing Account for deposit.&quot; &lt;&lt; endl;</TT>
<TT>61:     if (pin != card-&gt;pin() || !card-&gt;isAuthorized(account)) {</TT>
<TT>62: </TT>
<TT>63:         // Incorrect PIN or card not authorized; throw an</TT>
<TT>64:         // exception.</TT>
<TT>65:         cout &lt;&lt; &quot;  Authorization failed.&quot; &lt;&lt; endl;</TT>
<TT>66:         throw AuthorizationException();</TT>
<TT>67:     }</TT>
<TT>68: </TT>
<TT>69:     cout &lt;&lt; &quot;  Authorization succeeded; forwarding deposit &quot; &lt;&lt;</TT>
<TT>70:             &quot;request to Account.&quot; &lt;&lt; endl;</TT>
<TT>71:     return account-&gt;deposit(amount);</TT>
<TT>72: }</TT>
<TT>73: </TT>
<TT>74: CORBA::Float ATMImpl::getBalance(ATMCard_ptr card, Account_ptr</TT>
<TT>75:         account, CORBA::Short pin) throw (AuthorizationException) {</TT>
<TT>76: </TT>
<TT>77:     cout &lt;&lt; &quot;ATM: Authorizing Account for balance.&quot; &lt;&lt; endl;</TT>
<TT>78:     if (pin != card-&gt;pin() || !card-&gt;isAuthorized(account)) {</TT>
<TT>79: </TT>
<TT>80:         // Incorrect PIN or card not authorized; throw an</TT>
<TT>81:         // exception.</TT>
<TT>82:         cout &lt;&lt; &quot;  Authorization failed.&quot; &lt;&lt; endl;</TT>
<TT>83:         throw AuthorizationException();</TT>
<TT>84:     }</TT>
<TT>85: </TT>
<TT>86:     cout &lt;&lt; &quot;  Authorization succeeded; forwarding balance &quot; &lt;&lt;</TT>
<TT>87:             &quot;request to Account.&quot; &lt;&lt; endl;</TT>
<TT>88:     return account-&gt;balance();
89: }</TT> </FONT></PRE>
<P>Again, the implementation in <TT>ATMMain.cpp</TT> is one that can be mostly borrowed
from somewhere else. In this case, because an <TT>ATM</TT> interacts with the <TT>BankServer</TT>
much the same way as a <TT>Bank</TT> does, you can borrow the code from <TT>BankMain.cpp</TT>
and m