SOAP/XML Must Mature Quickly
CORBA, J2EE provide valuable experience for future middle-tier interoperability challenges.
by Jim Fawcette

Chris Horn, Chairman, Iona Technologies

As chairman of Iona Technologies, Dr. Christopher J. Horn runs a company that helps corporations tie together many technologies, from legacy systems to the bleeding edge of object-oriented programming. This makes Horn well qualified to put the emerging landscape in perspective—from XML and SOAP, to Java 2 Enterprise Edition, from wireless to peer-to-peer networking. XML Magazine's James Fawcette traveled to Iona's Dublin, Ireland, headquarters to interview Horn about these technologies and their importance in the corporate middleware market. This interview is edited for conciseness and clarity.

Fawcette: Iona was the first company to demonstrate SOAP/EJB/CORBA interoperabililty, and you're a co-submitter of SOAP. From your independent perspective, how rapidly do you see XML and SOAP being adopted?
Horn: It is in the early days; nevertheless, we see widespread corporate interest in employing SOAP for Internet and extranet use rather than for intranets—more for applications that are outward looking from the corporation. XML and SOAP are more verbose than binary technologies such as CORBA or Enterprise JavaBeans (EJB), where one gets a stronger, better-performance coupling.

Fawcette: Corporations seem to be in the prototyping and evaluating phase with XML and SOAP. What has to be done before widespread adoption happens?
Horn: Yes, it is very much a learning experience. The basic technology is being extended to handle issues such as transactions and security. Until enterprise capability has been demonstrated in SOAP, there will be resistance to widespread use. It is coming, though.

Fawcette: Do you mean that the technology needs to be improved, or that customers need to see others deploy systems?
Horn: Both. This is much like 1993 when CORBA was an emerging technology. A few pioneers were willing to adopt it, and that opened the floodgates in 1995, '96, and '97. We can expect widespread adoption of XML and SOAP in 12 to 18 months.
Fawcette: I understand that you are working on follow-on specifications for SOAP, encompassing security, transactions, QOS. Can you explain those and tell us what their status is?
Horn: In the CORBA specification, security levels vary from straightforward SSL to full-scale authentication, including the ability to handle repudiation of access rights. Similarly, there are sophisticated transaction models around full two-phase commit. For SOAP, in most applications, a simpler, lighter-weight, high-performance model will suffice. But some less widely used applications require more. Quality of service requirements also have different levels, from low-band sync and rollover to synchronous and asynchronous messaging, publish-and-subscribe, and notification. These are just different communications paradigms underlying presentation syntax of something like SOAP. You could say that this doesn't really matter in an XML-based system like SOAP, but in practice, we feel that there are things you can do to make capabilities such as publish-and-subscribe easier to use for the developer.