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287 lines
13 KiB
287 lines
13 KiB
<HTML>
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<HEAD>
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<TITLE> DwPopClient Man Page </TITLE>
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</HEAD>
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<BODY BGCOLOR="#FFFFFF">
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<H2>
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<FONT COLOR="navy"> NAME </FONT>
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</H2>
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<P>
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DwPopClient -- Class for handling the client side of a POP session
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<H2>
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<FONT COLOR="navy"> SYNOPSIS </FONT>
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</H2>
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<PRE>class DW_EXPORT DwPopClient : public <A HREF="protocol.html">DwProtocolClient</A> {
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public:
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enum {
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kCmdNoCommand=0,
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kCmdUser,
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kCmdPass,
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kCmdQuit,
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kCmdStat,
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kCmdList,
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kCmdRetr,
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kCmdDele,
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kCmdNoop,
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kCmdRset,
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kCmdApop,
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kCmdTop,
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kCmdUidl
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};
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<A HREF="pop.html#DwPopClient">DwPopClient</A>();
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virtual ~DwPopClient();
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virtual int <A HREF="pop.html#Open">Open</A>(const char* aServer, DwUint16 aPort=110);
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DwObserver* <A HREF="pop.html#SetObserver">SetObserver</A>(DwObserver* aObserver);
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int <A HREF="pop.html#StatusCode">StatusCode</A>() const;
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const DwString& <A HREF="pop.html#SingleLineResponse">SingleLineResponse</A>() const;
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const DwString& <A HREF="pop.html#MultiLineResponse">MultiLineResponse</A>() const;
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int <A HREF="pop.html#User">User</A>(const char* aName);
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int Pass(const char* a<A HREF="pop.html#Pass">Pass</A>wd);
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int <A HREF="pop.html#Quit">Quit</A>();
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int <A HREF="pop.html#Stat">Stat</A>();
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int <A HREF="pop.html#List">List</A>();
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int <A HREF="pop.html#List">List</A>(int aMsg);
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int <A HREF="pop.html#Retr">Retr</A>(int aMsg);
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int <A HREF="pop.html#Dele">Dele</A>(int aMsg);
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int <A HREF="pop.html#Noop">Noop</A>();
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int <A HREF="pop.html#Rset">Rset</A>();
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int <A HREF="pop.html#Apop">Apop</A>(const char* aName, const char* aDigest);
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int <A HREF="pop.html#Top">Top</A>(int aMsg, int aNumLines);
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int <A HREF="pop.html#Uidl">Uidl</A>();
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int <A HREF="pop.html#Uidl">Uidl</A>(int aMsg);
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};
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</PRE>
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<H2>
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<FONT COLOR="navy"> DESCRIPTION </FONT>
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</H2>
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<P>
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<B><TT>DwPopClient</TT></B> is a class that handles the client side of a
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POP session. Specifically, <B><TT>DwPopClient</TT></B> provides facilities
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for opening a connection to a POP server, sending commands to the server,
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receiving responses from the server, and closing the connection. The protocol
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implemented is the Post Office Protocol version 3, as specified in RFC-1939.
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<P>
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<B><TT>DwPopClient</TT></B> is derived from
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<B><TT><A HREF="protocol.html">DwProtocolClient</A></TT></B>. For information
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about inherited member functions, especially member functions for detecting
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failures or errors, see the man page for
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<B><TT>DwProtocolClient</TT></B>.
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<P>
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In a POP session, the client sends commands to the server and receives responses
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from the server. A client command consists of a command word and zero or
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more argument words. A server response consists of a single line status response,
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which may be followed immediately by a multi-line response. The first word
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of the status response is either +OK or -ERR, indicating the success or failure
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of the command. The status line may also contain other information requested
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by the client.
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<P>
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<B><TT>DwPopClient</TT></B> has only a default constructor. On Win32 platforms,
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it is possible for the constructor to fail. (It calls WSAStartup().) You
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should verify that the constructor succeeded by calling the inherited member
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function <B><TT>DwProtocolClient::LastError()</TT></B> and checking for a
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zero return value.
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<P>
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To open a connection to the server, call the member function
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<B><TT>Open()</TT></B> with the name of the server as an argument.
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<B><TT>Open()</TT></B> accepts an optional argument that specifies the TCP
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port that the server listens to. The default port is the standard POP port
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(110). <B><TT>Open()</TT></B> may fail, so you should check the return value
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to verify that it succeeded. To close the connection, call the inherited
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member function <B><TT>DwProtocolClient::Close()</TT></B>. To check if a
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connection is open, call the inherited member function
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<B><TT>DwProtocolClient::IsOpen()</TT></B>. <B><TT>IsOpen()</TT></B> returns
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a boolean value that indicates whether or not a call to
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<B><TT>Open()</TT></B> was successful; it will not detect failure in the
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network or a close operation by the remote host.
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<P>
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For each POP command, <B><TT>DwPopClient</TT></B> has a member function that
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sends that command and receives the server's response. If the command takes
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any arguments, then those arguments are passed as function arguments to the
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command function. The command functions return the first character of the
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server's response, which will be '+' if the command succeeded or '-' if the
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command failed. In some cases, because of a communications error or some
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other error, it is not possible for the command function to send the command
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or receive the response. When this happens, the command function will return
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0. You can determine the precise error or failure by calling the inherited
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member functions <B><TT>DwProtocolClient::LastError()</TT></B> or
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<B><TT>DwProtocolClient::LastFailure()</TT></B>.
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<P>
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After each command is sent, <B><TT>DwPopClient</TT></B> receives the server's
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response and remembers it. The member function
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<B><TT>StatusCode()</TT></B> returns the first character of the server's
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status response; it will be '+' or '-', indicating success or failure, or
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zero if no response was received from the server.
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<B><TT>SingleLineResponse()</TT></B> returns the entire single line status
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response from the server, including the initial "+OK" or "-ERR" status word.
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<P>
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The server sends a single-line response, including a status code, for all
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POP commands. For some commands, such as when the client requests a mail
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message, the server sends a multi-line text response immediately following
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the single-line status response. Multi-line text responses can be received
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in either of two ways. The simplest way is to call the member function
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<B><TT>MultiLineResponse()</TT></B> after a command completes successfully.
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This simple method works fine for non-interactive applications. It can be
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a problem in interactive applications, however, because there is no data
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to display to a user until the entire multi-line response is retrieved. An
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alternative method allows your program to retrieve the multi-line response
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one line at a time as it is received. To use this method, you must define
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a subclass of <B><TT>DwObserver</TT></B> and assign an object of that class
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to the <B><TT>DwPopClient</TT></B> object using the member function
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<B><TT>SetObserver()</TT></B>. <B><TT>DwObserver</TT></B> is an abstract
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class, declared in protocol.h, that has just one pure virtual member function
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<B><TT>Notify()</TT></B>. After each line of the multi-line response is received,
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<B><TT>DwPopClient</TT></B> will call the <B><TT>Notify()</TT></B> member
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function of its assigned <B><TT>DwObserver</TT></B> object. Each invocation
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of <B><TT>Notify()</TT></B> should call the <B><TT>DwPopClient</TT></B> member
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function <B><TT>MultiLineResponse()</TT></B> to retrieve the next line of
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the text response. Note that you cannot use both of these methods at the
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same time: if an observer is assigned,
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<B><TT>MultiLineResponse()</TT></B> returns only the last line received,
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not the entire multi-line response.
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<H2>
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<FONT COLOR="navy"> Public Member Functions </FONT>
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</H2>
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<P>
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<FONT COLOR="teal"><B> <A NAME="DwPopClient">DwPopClient</A>() </B></FONT>
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<P>
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Initializes the <B><TT>DwPopClient</TT></B> object. It is possible for the
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constructor to fail. To verify that the constructor succeeded, call the member
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function <B><TT>LastError()</TT></B> and check that it returns zero. (In
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the Win32 implementation, the constructor calls the Winsock function
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<B><TT>WSAStartup()</TT></B>, which may fail.)
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<P>
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<FONT COLOR="teal"><B> virtual int <A NAME="Open">Open</A>(const char* aServer,
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DwUint16 aPort=110) </B></FONT>
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<P>
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Opens a TCP connection to the server <B><TT>aServer</TT></B> at port
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<B><TT>aPort</TT></B>. <B><TT>aServer</TT></B> may be either a host name,
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such as "news.acme.com" or an IP number in dotted decimal format, such as
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"147.81.64.60". The default value for <B><TT>aPort</TT></B> is 110, the
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well-known port for POP3 assigned by the Internet Assigned Numbers Authority
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(IANA).
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<P>
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If the connection attempt succeeds, the server sends a response.
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<B><TT>Open()</TT></B> returns the server's status code ('+' or '-'). The
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full response from the server can be retrieved by calling
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<B><TT>SingleLineResponse()</TT></B>.
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<P>
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If the connection attempt fails, <B><TT>Open()</TT></B> returns 0. To determine
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what error occurred when a connection attempt fails, call the inherited member
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function <B><TT>DwProtocolClient::LastError()</TT></B>. To determine if a
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failure also occurred, call the inherited member function
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<B><TT>DwProtocolClient::LastFailure()</TT></B>.
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<P>
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<FONT COLOR="teal"><B> DwObserver*
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<A NAME="SetObserver">SetObserver</A>(DwObserver* aObserver) </B></FONT>
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<P>
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Sets the observer object that interacts with the
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<B><TT>DwPopClient</TT></B> object to retrieve a multi-line response. If
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an observer is set, <B><TT>DwPopClient</TT></B> will call the observer's
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<B><TT>Notify()</TT></B> method after each line of the multi-line response
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is received. To remove an observer, call <B><TT>SetObserver()</TT></B> with
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a NULL argument. <B><TT>SetObserver()</TT></B> returns the previously set
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observer, or NULL if no observer was previously set.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="StatusCode">StatusCode</A>() const
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</B></FONT>
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<P>
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Returns the status code received from the server in response to the last
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client command. The status codes in POP3 are '+', indicating success, and
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'-', indicating failure. If no response was received,
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<B><TT>StatusCode()</TT></B> returns zero.
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<P>
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<FONT COLOR="teal"><B> const DwString&
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<A NAME="SingleLineResponse">SingleLineResponse</A>() const </B></FONT>
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<P>
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Returns the single line status response last received from the server. If
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no response was received, perhaps because of a communications failure,
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<B><TT>SingleLineResponse()</TT></B> returns an empty string.
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<P>
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<FONT COLOR="teal"><B> const DwString&
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<A NAME="MultiLineResponse">MultiLineResponse</A>() const </B></FONT>
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<P>
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If no observer is set for this object,
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<B><TT>MultiLineResponse()</TT></B> returns a string that comprises the entire
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sequence of lines received from the server. Otherwise, if an observer
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<I>is</I> set for this object, <B><TT>MultiLineResponse()</TT></B> returns
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only the most recent line received.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="User">User</A>(const char* aName)
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</B></FONT>
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<P>
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Sends the USER command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aName</TT></B> is the name of the user, which is sent in the command.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Pass">Pass</A>(const char* aPasswd)
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</B></FONT>
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<P>
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Sends the PASS command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aPasswd</TT></B> is the password, which is sent in the command.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Quit">Quit</A>() </B></FONT>
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<P>
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Sends the TQUIT command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Stat">Stat</A>() </B></FONT>
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<P>
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Sends the STAT command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="List">List</A>() <BR>
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int List(int aMsg) </B></FONT>
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<P>
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Sends the LIST command, with or without a message number, and returns the
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status code received from the server. If no response is received, the function
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returns zero.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Retr">Retr</A>(int aMsg) </B></FONT>
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<P>
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Sends the RETR command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aMsg</TT></B> is the message number, which is sent in the command.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Dele">Dele</A>(int aMsg) </B></FONT>
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<P>
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Sends the DELE command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aMsg</TT></B> is the message number, which is sent in the command.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Noop">Noop</A>() </B></FONT>
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<P>
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Sends the NOOP command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Rset">Rset</A>() </B></FONT>
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<P>
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Sends the RSET command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Apop">Apop</A>(const char* aName, const
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char* aDigest) </B></FONT>
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<P>
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Sends the APOP command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aName</TT></B> is the name of the user, which is sent in the command.
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<B><TT>aDigest</TT></B> is the digest argument for the command.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Top">Top</A>(int aMsg, int aNumLines)
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</B></FONT>
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<P>
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Sends the TOP command and returns the status code received from the server.
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If no response is received, the function returns zero.
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<B><TT>aMsg</TT></B> is the message number. <B><TT>aNumLines</TT></B> is
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the number of lines to send.
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<P>
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<FONT COLOR="teal"><B> int <A NAME="Uidl">Uidl</A>() <BR>
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int Uidl(int aMsg) </B></FONT>
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<P>
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Sends the TOP command, with or without a message number, and returns the
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status code received from the server. If no response is received, the function
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returns zero.
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</BODY></HTML>
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