Enterprise Applications Integration with XML and Java

That extends even to application programs not conceived of at the time the information was created'. From this aim, the term 'Enterprise Application Integration' (EAI) is derived, meaning the attempt to unify the vast amount of data that lies in isolated pools by enabling the systems that house those data to communicate with each other using common protocols.

It is the authors' purpose to promote this aim which they define as 'the seamless integration of business processes for the purposes of conducting business electronically'. Their intention is to help network developers get to grips with techniques that will enable them to do this.

But I'm not sure that they are successful, because the prevailing tone is abstract and theoretical, where it should be concrete and practical. There is a chapter entitled 'Parsing XML' which goes into detail about how to write an XML parser in Java, something that virtually no professional software writer would ever either want or need to do. Looking at the authors' rather unidiomatic code examples here, they would clearly benefit from reading the excellent The Elements of Java Style.

It also seems something of an omission that they have not seen fit to examine the technology in the light of commercial interests. It has been suggested that one well-known company has been deliberately trying to prevent precisely this sort of integrational drive. This is being done by adopting universal and platform-neutral protocols and extending them, often adding improvements.

Since the point about a protocol is that it should aspire to universality, the net result is that it is broken and usurped as the commercial property of a large corporation with the marketing resources to spread this unfortunate mutation throughout the world. This is a very important issue today and one that cannot be seen in isolation from the subject matter of this book.

Unfortunately, apart from rare glimpses of practicality, such as the discussion of the relative merits and demerits of SAX versus DOM parsers, and a library for persisting a graph of Java objects, we are left in largely academic territory, with few indications of how we can access resources that will be useful in designing commercial quality integrational software.

Alarm bells also begin to ring when we read another definition of EAI as: 'The sharing and/or exchange of data between systems for the purpose of providing a unified interface'. This is perhaps a Freudian slip, because the purpose is not to provide a 'unified interface', but to enable machines to talk to each other in a common language so we can rise above the idiocy and anarchy of having islands of data languishing in mutual incomprehensibility.

Anyone unfamiliar with the subject matter of this book could be forgiven for imagining that the authors are wrestling with these problems for the first time, so scant are the references to the large body of work done by others in this field. What most professional developers new to this field need to know, after the theoretical underpinnings have been conveyed to them, are things like: What are the most mature and consolidated technologies in this area? What development environments, tools and libraries are available? Which operating systems have been successfully integrated and by what means?

One final gripe, and unfortunately not an uncommon one these days, is that the book is padded out with over 40% of specifications and documentation that could easily be downloaded.