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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 <e32cons.h>

int HelloWorldL()

       {

       CConsoleBase* console = Console::NewL(_L("Hello World"), TSize( KConsFullScreen, KConsFullScreen));

       console->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(&threadAttr);

   retVal = pthread_create(&threadID, &threadAttr, ThreadEntryPoint, (void*)NULL );

   if(retVal == 0) {

       retVal = pthread_join(threadID1, (void**)&exitReason);

   }

</codeblock><codeblock xml:space="preserve">// Thread creation in Symbian OS

  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>