Using Protocol Adapters to Improve System Performance
Web Services are very good at what they were built for - loosely coupled HTTP based interaction - and may well be appropriate for your situation. However, protocol adapters may be a better fit for tightly coupled systems where you need high performance and seamless integration.
The primary disadvantage of SOAP/XML-based protocol adapters (ie, Web Services) is the performance overhead. For mission critical projects that have large amounts of data to transmit, Web Services is not always the best option. There is a cost to converting data to a common type format (a typical Web Service conversion to XML results in a 5 fold increase in size).
To improve performance, you need to change the protocol connecting your backend process. By implementing a wire protocol that is native to one of the two sides being connected in a typical SOA integration effort, protocol adapters can increase performance and scalability.
In addition to their performance benefits, J-Integra® protocol adapters allow you to do things you can't do with Web Services: pass objects by reference, callbacks, events, proper exception handling, etc. They also reduce complexity and risk in deployment, usability, and scalability.
Microsoft .NET to J2EE Interoperability Performance Analysis
The following whitepaper discusses the performance benefits of using the J-Integra® RMI-IIOP Adapter versus Web Services. Although not mentioned in this particular whitepaper, the J-Integra® DCOM and .NET Remoting Adapters also result in similar performance benefits when compared to Web Services.