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<concept id="GUID-CF6014E9-FB59-4715-B245-5826090DDF28" xml:lang="en"><title>Symbian
Platform vs UNIX</title><shortdesc/><prolog><metadata><keywords/></metadata></prolog><conbody>
<section id="GUID-977EFA64-8D61-44CA-9A89-64D8DB0F771E"> <title>Hello World</title><p>Assuming
that the user is new to the UNIX environment, writing a simple program that
displays a string on a console does not take more than a day’s effort. Its
simply 4-5 lines of code as shown below: </p><codeblock xml:space="preserve">#include &lt;stdio.h&gt;
int main(int argc, char** argv)
    {
    printf(“Hello world\n”);
    return 0;
    }</codeblock><p>The code contains a <codeph>main()</codeph> , one <codeph>printf</codeph> statement,
and one <codeph>#include&lt; &gt;</codeph>. By convention UNIX applications will
map descriptor 0 with standard input (<codeph>STDIN</codeph>), descriptor
1 with standard output (<codeph>STDOUT</codeph>), and descriptor 2 with standard
error (<codeph>STDERROR</codeph>) of the process. So, there is no need to
create/open standard input/output/error for a process before using them. Notice
also that, <codeph>main()</codeph> takes two arguments. These arguments will
be read from the command prompt before invoking <codeph>main()</codeph> and
will be passed to main. These arguments are not mandatory; they can be ignored.
No additional work is needed for having these arguments. </p><p>If the user
attempts to display a string on a console using Symbian platform, a lot of
effort goes into collecting the materials, and for coding. The first time
the developer may find the code a little complex to understand.</p><codeblock xml:space="preserve">#include &lt;e32std.h&gt;
#include &lt;e32cons.h&gt;
int HelloWorldL()
       {
       CConsoleBase* console = Console::NewL(_L("Hello World"), TSize( KConsFullScreen, KConsFullScreen));
       console-&gt;Printf(_L(“Hello World\n”));
       delete console;
       return 0;
       }

TInt E32Main()
       {
       __UHEAP_MARK;
       CTrapCleanup* cleanup = CTrapCleanup::New();
       TInt retVal = KErrNone;
       if (cleanup)
           {
           TRAP(retVal, HelloWorldL());
           __ASSERT_ALWAYS(!retVal, User::Panic(_L("Hello-World PANIC"), retVal));
           //Destroy cleanup stack
           delete cleanup;
           }
       __UHEAP_MARKEND;
       return retVal;
       }
</codeblock><p>The code above has some header inclusions, two functions, and
some complicated codes. In Symbian platform, the entry function for an EXE
is <codeph>E32Main</codeph> (not main as in UNIX). The following actions are
done to print a message on a console: </p><ol>
<li id="GUID-11FE80AB-BD78-4A53-88D4-90E9CE3158EF"><p>Mark the heap using <codeph>__UHEAP_MARK</codeph> (not
mandatory).</p></li>
<li id="GUID-5292A0E8-5158-4A3B-89DC-095D570AEDA7"><p>Create the cleanup stack.
Have a top-level TRAP for the function <codeph>HelloWorldL()</codeph> function.</p></li>
<li id="GUID-E47E4F4F-EC51-4D7F-8254-0329A6DC1689"><p>In the <codeph>HelloWorldL()</codeph> function,
create a console object.</p></li>
<li id="GUID-8CAA7ADA-3EE1-470E-A376-DAD345066BF2"><p>Do print on the created
console object.</p></li>
<li id="GUID-8ABFB71E-A89A-4D02-9CBC-50FACC853805"><p>Delete the console.</p></li>
<li id="GUID-4FDC0B1D-0DAB-42AF-9E54-A53DBDD47327"><p>Delete the cleanup stack.</p></li>
<li id="GUID-187B70A6-D15E-4197-A742-372F6E385FEC"><p>Unmark the heap (not
mandatory if the heap is not marked). </p></li>
</ol><p>In Symbian platform, a console is not created by default; it has to
be created explicitly. Symbian platform does not give a rich set of APIs needed
to perform I/O operations on a console. The I/O operations that can be performed
on a console in Symbian platform are limited to:</p><ul>
<li><p>printing strings and reading one character at a time</p></li>
<li><p>getting cursor position </p></li>
</ul><p>In case the user is interested in command line arguments, it takes
some more additional work. The user must read explicitly from the command
prompt by using the APIs provided by Symbian platform.</p>     </section>
<section id="GUID-3FC28B5E-4D46-4E33-90E8-AB9A1FBC038E"><title>File I/O</title><p>This
section compares the ease of programming in the P.I.P.S. environment against
programming on Symbian platform.</p><codeblock xml:space="preserve">/* File I/O in UNIX environment */
  FILE* fp = fopen(“file.txt”, w);
  if (fp) {
     fprintf(fp, “Write some data”);
     fclose();
  }
</codeblock><codeblock xml:space="preserve">//File I/O in Symbian platform
  RFs fSession;
  User::LeaveIfError(fSession.Connect());
  RFile file;
  ret = file.Open(fSession, _L(“file.txt”), EFileWrite);
  if (ret) 
     {
     ret = file.Create(fSession, _L(“file.txt”), EFileWrite);
     }
  if (!ret) 
     {
     file.Write(_L8(“Write some data”));
     }
  file.Close();
  fSession.Close();
</codeblock><p>The example above shows the complexity of the code in Symbian
platform for doing simple file I/O. In addition to coding complexity, the
user must include and link with:</p><ul>
<li><p><filepath>efsrv.lib</filepath> for any file-related operation</p></li>
<li><p><filepath>esock.lib</filepath> for network-related operation</p></li>
<li><p><filepath>commdb.lib</filepath> for selecting IAPs </p></li>
</ul><p>Since most of the resources under Symbian platform are accessed through
client/server IPC, the user must connect with the corresponding server before
doing any operation and close the session on completion of the operation.
For example: <ul>
<li><p>connect with the file server before file operations</p></li>
<li><p>connect with the socket server for socket-related operation</p></li>
<li><p>connect to the communication server before serial communication operation</p></li>
</ul></p><p>P.I.P.S. eliminates all these operations. P.I.P.S. allows the
user to code, as if it were done for the UNIX or Linux environment and lets
the user link the application with P.I.P.S.</p></section>
<section id="GUID-AFAE7FDA-8829-4FF7-991F-D65EBAA652F2"><title>Thread creation</title><p>This
section deals with thread creation in the UNIX and Symbian platform environments.</p><codeblock xml:space="preserve">/* Thread creation in UNIX environment*/
   void* ThreadEntryPoint( void* aParam );
   int exitReason = 0;
   int retVal  = 0;
   pthread_t threadID = 0;
   pthread_attr_t threadAttr;
   pthread_attr_init(&amp;threadAttr);
   retVal = pthread_create(&amp;threadID, &amp;threadAttr, ThreadEntryPoint, (void*)NULL );
   if(retVal == 0) {
       retVal = pthread_join(threadID1, (void**)&amp;exitReason);
   }
</codeblock><codeblock xml:space="preserve">// Thread creation in Symbian Platform
  TInt ThreadEntryPoint( TAny* aData );
  …
  RThread thread;
  thread.Create(_L("MY-THREAD"), ThreadEntryPoint, 4096, NULL, NULL);
  TRequestStatus stat;
  thread.Logon(stat);
  //Start executing the thread.
  thread.Resume();
  //Wait for the thread to die.
  User::WaitForRequest(stat);
  exitReason = thread.ExitReason();
  thread.Close();
</codeblock><p>In addition the difference in the code for creating threads
using <codeph>pthread_create</codeph> and <xref href="GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5.dita#GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5/GUID-6C840907-C3F7-34B7-97DB-CEDBA68EA277"><apiname>RThread::Create()</apiname></xref>,
a thread created using <xref href="GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5.dita#GUID-B0E661BC-4058-3256-B9C3-5A4FD52F6DE5/GUID-6C840907-C3F7-34B7-97DB-CEDBA68EA277"><apiname>RThread::Create()</apiname></xref> also expects the <codeph>ThreadEntryPoint()</codeph> function
to create its own vcleanup stack and a top-level TRAP, if required. Else,
the thread may crash or panic. But this does not have to be done for a thread
created using <codeph>pthread_create. pthread_create</codeph> does that for
the developer.</p></section>
</conbody></concept>