Use of Integration Middlewares to Increase Maintainability in Integrated Systems

Advisors: José Carlos Maldonado - Paulo Meirelles


Context: Integration servers usually concentrates all relevant code and data to allow the integrated applications to communicate. Problem: In many cases the applications also need to be modified in order to reply to the integration server messages, increasing coupling and reducing the maintainability. Objective: This study aims to prove that a system composed by integrated parts using middlewares can be build, without compromise maintainability. Method: Two systems with and without use of middlewares are analyzed with the use of metrics defined on ISO9126-3:2002 in order to validate the hypothesis. Results: As the metrics defined on ISO9126-3:2002 given scores in absulute values any improvement in the scores will be considered satisfactory. Conclusion: The use of middlewares is a promising step towards improving the quality of integrated systems.


There are cases where a single existing system does not meet a set of raised requirements. The use of a group of systems instead of just one it is an option but doing so also bring some drawbacks such as multiple user accounts, different user experience and duplicated information. To reduce the drawbacks the systems can be integrated into a new composed system.

Problems and Gaps

The integration of independently designed and developed systems, in many cases, require modifications in each of the integrated parts. That occurs because the parts were not designed for integration but actually to serve specific purposes. In some cases where the source code is available the changes can be made by the integrators but in other cases the requirements need to be addressed to the company or people developing and maintaining it. None of the two scenarios are ideal because in both cases the modifications would impact system maintainability.

Research Questions

How to build a system composed by integrated parts without compromise maintainability?


  1. The use of an integration server with plugable middlewares will reduce coupling between parts and integration server increasing Maintainability.
  2. The use of middlewares will impact system’s Efficiency in an acceptable level (up to 5%).
  3. The use of middlewares will improve the integration server Portability.


The ISO9126-3:2002 product quality metrics will be used to evaluate a real system in the following Quality Attributes and its subcharacteristics:


  • Analyzability
  • Changeability
  • Stability
  • Testability
  • Compliance


  • Adaptability
  • Installability
  • Co-existence
  • Replaceability
  • Compliance


  • Time behaviour
  • Resource utilization
  • Compliance

The Quality Attributes will be measured using the metrics described on the ISO9126-3:2002 in two real integrated systems already in use: the Software Público Brasileiro (SPB) and Interlegis’ Colab (IC). The systems were choosen because both are Open-Source and use the same integration server (called Colab), and one of then has with modifications directly on Colab’s source code (IC) and the other uses middlewares (SPB). The applied metrics will result on absulute values from 0 to 1 for each subcharacteristic. Any score improvement will be considered for Maintainability and Portability and a loss up to 0.05 on Efficiency will be considered satisfactory.