A Comparative Code Example
The advantage of using the Essential Networking Module can be demonstrated by comparing its code to code for the same operations using traditional C++. If you have experience in network programming in C++, you may have used code like this to look up a network host and all its aliases from a DNS server:
// Without the Essential Networking Module,
// using any standard C++ library
const char* s = "209.119.36.154"; // or "www.roguewave.com"
string hostname;
vector<std::string> aliases;
unsigned long address;
vector<unsigned long> addresses;
struct hostent* hp = 0;
// Is the string a dotted decimal address or host name?
unsigned long addr = inet_addr(s);
// Do DNS lookup for host information
if(addr != (unsigned long)-1)
hp = gethostbyaddr((char*)&addr, sizeof(addr), AF_INET);
else
hp = gethostbyname(s);
// If DNS query was successful, continue
if(hp != 0)
{
// Get primary address
address = ((struct in_addr*) // 1
((hp->h_addr_list)[0]))->s_addr;
// Get host name
hostname = hp->h_name; // 2
// Get aliases
{ // 3
int n = 0;
if(hp->h_aliases)
for(char **ptr = hp->h_aliases; *ptr; ++ptr)
++n; // count aliases
aliases.resize(n);
for(int i = n; i--;)
aliases[i] = (hp->h_aliases)[i];
}
// Get addresses
{ // 4
int n = 0;
for(char **ptr = hp->h_addr_list; *ptr; ++ptr)
++n;
addresses.resize(n);
for(int i = n; i--; )
addresses[i] = ((struct in_addr*)
((hp->h_addr_list)[i]))->s_addr;
}
}
With the Essential Networking Module, you can write the same code as follows:
const char* s = "209.119.36.154"; // or "www.roguewave.com"
RWInetHost host(s);
unsigned long address = host.getAddress(); // 1
RWCString hostname = host.getName(); // 2
RWTValVector<RWCString> aliases = host.getAliases(); // 3
RWTValVector<unsigned long> addresses = host.getAddresses();
// 4
In both cases, the code accomplishes the same tasks: gets the primary address on //1; gets the host name on //2; gets the aliases on //3; and gets the other addresses on //4. However, the second example does the job with fewer steps, using a simpler, more intuitive interface, and less development time. Furthermore, it provides much more error-checking and type-safety than the first example.
