Extract Subject/Issuer from <X509Certificate>

Hi,
I know that in .NET it's possible to take a signed XML file and to easily extract the Subject and the Issuer etc of the certificate from the <X509Certificate> element.

{Pseudo code}
KeyInfoX509Data x509Data = SignedXmlFile.KeyInfo;
X509Certificate2 certificate = x509Data.Certificates)
X509Certificate2 signerCert = certificate;
Display (signerCert.SubjectName.Name)
Display (signerCert.Issuer.Name)

I need to extract the same information from a signed XML file using the OpenSSL library in C++ in Linux.

Can anyone help me out with what I should be doing.

Thanks in advance,
Michael