The degree of an industry is based upon the ability of that industry to move forward through continual advances and developments in new technology. The porcelain enamel industry is a good example of such a success story where innovations in technology have controlled its progress and brought it to the viable business it is today.     


 it is today在句子里是定语从句，省略了关系代词that，先行词是   the viable business。全句含义是说：搪瓷业的成功，正是由于工艺技术的革新掌握了这一工业的进展，使它成为今天这样一个具有生命的企业。