<!-- page12.html,v 1.16 2003/08/19 15:08:26 schmidt Exp --> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META NAME="Author" CONTENT="James CE Johnson"> <TITLE>ACE Tutorial 015</TITLE> </HEAD> <BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> <CENTER><B><FONT SIZE=+2>ACE Tutorial 015</FONT></B></CENTER> <CENTER><B><FONT SIZE=+2>Building a protocol stream</FONT></B></CENTER> <P> <HR WIDTH="100%"> A quick look at the Protocol_Task header... <HR> <PRE> <font color=red>// page12.html,v 1.16 2003/08/19 15:08:26 schmidt Exp</font> <font color=blue>#ifndef</font> <font color=purple>PROTOCOL_TASK_H</font> <font color=blue>#define</font> <font color=purple>PROTOCOL_TASK_H</font> <font color=blue>#include</font> "<A HREF="../../../ace/Task.h">ace/Task.h</A>" <font color=blue>#if !defined</font> (<font color=purple>ACE_LACKS_PRAGMA_ONCE</font>) <font color=blue># pragma</font> <font color=purple>once</font> <font color=blue>#endif</font> <font color=red>/* ACE_LACKS_PRAGMA_ONCE */</font> <font color=red>/* A typical ACE_Task<> derivative that adds a few things appropriate to protocol stacks. To keep things a little simpler, we prevent activation of the task and just borrow the thread of control from the calling method in all cases. */</font> class Protocol_Task : public ACE_Task<ACE_MT_SYNCH> { public: typedef ACE_Task<ACE_MT_SYNCH> inherited; Protocol_Task (void); ~Protocol_Task (void); <font color=red>// open() is invoked when the task is inserted into the stream.</font> virtual int open (void *arg); <font color=red>// close() is invoked when the stream is closed (flags will be set</font> <font color=red>// to '1') and when the svc() method exits (flags will be '0').</font> virtual int close (u_long flags); <font color=red>// As data travels through the stream, the put() method of each task</font> <font color=red>// is invoked to keep the data moving along.</font> virtual int put (ACE_Message_Block *message, ACE_Time_Value *timeout); <font color=red>// We're obligated to provide this signature even though we won't be</font> <font color=red>// allowing this object to be activated.</font> virtual int svc (void); protected: <font color=red>// Called by put() or svc() as necessary to process a block of data.</font> int process (ACE_Message_Block *message, ACE_Time_Value *timeout); <font color=red>// Tasks on the writer (downstream) side of the stream are called</font> <font color=red>// upon to send() data that will ultimately go to the peer.</font> virtual int send (ACE_Message_Block *message, ACE_Time_Value *timeout); <font color=red>// Tasks on the reader (upstream) side will be receiving data that</font> <font color=red>// came from the peer.</font> virtual int recv (ACE_Message_Block *message, ACE_Time_Value *timeout); }; <font color=blue>#endif</font> <font color=red>/* PROTOCOL_TASK_H */</font> </PRE> <P><HR WIDTH="100%"> <CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page13.html">Continue This Tutorial</A>]</CENTER>