1. COTS Reuse

2. Objectives
To introduce the notion of COTS reuse and to discuss the different approaches to COTS reuse that may be adopted
To explain the benefits and problems of the different approaches to COTS reuse
To discuss the issues around the development of software by configuring and adapting COTS systems and components

3. Topics covered COTS solution systems COTS integrated systems
Construction by configuration
Configuration issues and problems

4. Commercial Off-the-Shelf Systems (COTS)
COTS systems are complete application systems (not components of some larger system) that can be deployed and run as independent systems.
Reuse of COTS systems involves adapting and configuring these systems for a specific operational environment.
Examples
Develop Excel spreadsheets to support project costing
Configure a patient record system for a specific medical practice

5. Requirements issues
The top-down process of identifying requirements then building a system to deliver these requirements does not work
Rather, requirements engineering is an iterative process
What is wanted by stakeholders?
What is available from existing systems?
What is available from the system that is chosen
Stakeholders expectations have to be managed
The delivered system may not provide them with what they want

6. General benefits
Extensive functionality can be delivered more quickly and more cheaply than for applications that are specially developed for specific requirements
Systems should be more reliable because they are widely used and extensively tested
Businesses can focus on their core activity rather than concerning themselves with IT systems development
Technology updates may be simplified as operating platforms evolve

7. General problems
Choosing the right COTS system for a particular organisation can be difficult
There may be a lack of expertise available to support systems development
System evolution is controlled by the system vendor rather than the system buyer
New versions may include unwanted functionality; Required functionality may not be included
Source code is not available so buyers are reliant the system vendor continuing to support the product
Product documentation is often inadequate
Difficult to estimate the costs and risks of system configuration and integration

8. Commercial Off-the-Shelf Systems (COTS)
COTS-solution systems
Choose a generic system that has been developed to deliver some business function and adapt that system to the needs of a particular organisation.
COTS-integrated systems
Develop a new system by choosing a number of COTS systems and integrating these to deliver combined functionality. Additional software (glueware) is required to make these systems work together.

9. COTS solution systems Domain-specific applications
Application systems that are designed to support a particular business application
For example, an appointment management system for dentists
Generic applications
Generic systems that can be used with a range of other applications
For example, clients or spreadsheets
Enterprise Resource Planning (ERP) systems
Generic business systems built around a shared database

10. Domain specific applications
Domain-specific applications are (usually) business systems that have been designed to support a particular business function
Document management
Payroll and salaries
Student record management
Event booking
Usually have a basis in a specific system which has been generalised for wider use
Systems incorporate assumptions made by the vendor about the domain of application
E.g. students will only be registered for a degree at one university

11. Benefits
Designed for a specific application area so provide extensive, integrated functionality to support that area
A specific user community may be created to share knowledge of problems and how to use the system effectively
Usually designed to support information sharing

12. Problems
The assumptions made by the vendor may not hold for the user of the system
We shall see later a system that had problems because it assumed that it would be used under a particular legal system
The process of use may not match user processes
Systems may only be available on limited platforms
Sometimes expensive
Reliant on continuing support from a single vendor
May be no or limited API for integration with other systems

13. Generic applications
Generic applications are general-purpose systems such as Excel or clients. That is, they offer functionality that is likely to be useful in many different areas of work
They may be configured to create personal systems
Excel, especially, has very powerful configuration features that allow application-oriented spreadsheets to be created
More commonly, generic applications are incorporated as part of COTS-integrated systems

14. Benefits Usually cheap Widely used and tested so fairly reliable
May already be licensed for use by the organisation procuring the system
May be supported on different platforms
Users may already be familiar with their user interface (e.g. if Word is used for text input)
Incorporate extensive functionality so may be used in a range of different application types

15. Problems
As the systems are designed for stand-alone use, the API may not be well-defined or documented
This causes difficulties in integration with other systems
Undocumented system features may be incompatible with or may conflict with other COTS systems
System versions on different platforms may not be completely compatible
Systems are regularly superceded by new versions which may be incompatible
The system vendor may not support older versions of the system

16. ERP systems
ERP systems are intended to provide support for all data and processes in an organisation in a single, integrated system
Most large companies have now adopted some form of ERP system
Everything is integrated around a single database
Generally, ERP systems include a number of business-focused modules (e.g. manufacturing, supply chain, human resources, etc.) that are integrated using a set of process workflows and business rules
Primarily used by large companies and organisations
SAP and Oracle are the major vendors of ERP systems

17. Systems architecture Purchasing Supply chain Logistics CRM
Processes
Processes
Processes
Processes
Business rules
System database

18. ERP systems development
Modules in an ERP system are large and complex and extensive configuration is needed to describe the processes and rules of a business
Configuration involves:
Selection of modules - what business activities should be/can be integrated
Development of process workflows
Specification of schemas
Definition of business rules
Definition of input forms
Definition of output reports

19. Benefits Integration across business functions.
Data from one function is visible to other functions
Reduces data duplication
Reduces the number of separate software systems that have to be managed and maintained

20. Problems
Very complex to configure ERP systems - thousands of tables and reports may have to be defined
There may be a mismatch between the processes and rules supported by the ERP system and an organisation’s processes
Forces a standard way of working on businesses
Can therefore lose competitive edge because of better processes than competitors
Difficult to integrate with legacy systems

21. COTS integrated systems
This approach is used when there is no single COTS system that can provide the required functionality or where it is essential for a new system to integrate with existing organisational systems
An application is constructed by integrating COTS systems from different vendors
Middleware is used to support communications between these different systems

22. Solution vs integrated COTS
COTS solution systems
COTS integrated systems
Single product that provides required functionality
Generic solution with standard processes
Focus is on configuration
System vendor is maintainer
System vendor provides infrastructure
Several heterogeneous products integrated to provide customised functionality
Flexible solutions for specific processes
Focus is on integration
System owner is maintainer
System owner provides infrastructure

23. E-procurement system

24. COTS products reused
On the client, standard and web browsing programs are used.
On the server, an e-commerce platform has to be integrated with an existing ordering system which was part of an ERP system.
This involves writing an adaptor so that they can exchange data.
An system is also integrated to generate for clients. This also requires an adaptor to receive data from the ordering and invoicing system.

25. Benefits Extends the functionality of existing systems
Faster system development and deployment
E.g. the e-procurement system was delivered in 9 months rather than the predicted 3 years
Infrastructure upgrades are provided by the system vendors
E.g. systems are updated for new releases of the OS

26. Problems Architectural mismatch Performance problems
The architectural models of the different products may be incompatible e.g. they may use different event models. Middleware may have to be written to resolve this problem
Performance problems
Systems with acceptable performance as stand-alone systems may not be as effective when combined with other systems
Problems of upgrade management
Different vendors may have different upgrade cycles
Security issues
The security features of the different systems may be incompatible. Integration may only be possible by weakening security
Example of architectural mismatch is who is in control. Each COTS product may assume that it is in control thus making it hard for them to work together
Also issues of overlapping infrastructure - each product may supply overlapping functionality of libraries etc. This may lead to very large systems and performance problems.

27. Construction by Configuration: COTS application engineering

28. Construction by configuration (C-b-C)
Software development with reuse rarely means reusing domain abstractions without change.
The reusable abstractions have to be configured to adapt them to their local circumstances of use.
This can range from simple parameter setting through the definition of business rules to special purpose component development.
C-b-C also may also include configuring the process as well as configuring the software that is the way people work has to change to meet the demands of the software.
We are still programming - but using a local programming model rather than a generic model.

29. Reuse and configuration
Components and services are intended to be used with limited configuration. Here the adaptation and configuration is often in the ‘glue code’ used to link these entities.
System families are configured by adapting specified parts of the system code.
ERP systems and generic COTS, by contrast, are designed for configuration without access to the source code of the system.

30. COTS configuration
COTS solution systems are designed for configuration
The systems have been designed to include generic functionality and abstractions from the domain which are configured for each specific customer through configuration interfaces
Programming is therefore configuration programming rather than programming in a conventional language
Configuration programming can be a (very) long-term process
The current Spanish en-route air traffic control system is being reconfigured for use in the UK. The process is anticipated to take 6 years.

31. Configuration
I use the term ‘configuration’ to cover both customisation and adapting software to a specific execution environment.
Adapting the system to reflect:
The specific needs of a customer (e.g. a hospital);
The requirements of a user or group of users (e.g. maternity unit or physiotherapy or both);
Interaction with other systems;
The characteristics of the platform on which the software executes.

32. Configuration activities
Selecting required functionality
Defining a data model
Defining business rules
Defining workflows
Defining external interactions
Defining the user interface
Defining reports produced
Setting platform parameters
Data re-engineering
Re-defining business processes
EXPLAIN WHAT THESE MEAN

33. A patient management system
We have followed the deployment of a patient management system (PIMS) for mental healthcare in Edinburgh, Scotland.
Based around a generic COTS-package developed for hospitals in England.
This was designed to be adapted for supporting different kinds of clinic including mental healthcare.
Scotland has its own legal system and laws and healthcare is a devolved responsibility. The Scottish Executive sets its own targets and priorities for healthcare.
EXPLAIN ABOUT HEALTHCARE TARGETS

34. Procurement issues
A major influence in choosing the particular COTS system was that it offered the opportunity for hospital managers (rather than clinical staff) to control how information was recorded.
The Executive placed a tight deadline on hospitals for reporting against a set of targets.
There was little time to carry out a detailed comparison of alternatives and this system had already been successfully deployed elsewhere.
CHANGING THE POLITICAL POWER BASE IN HOSPITALS

35. Software engineering
Configuring the data model required for a particular set of clinics.
i.e. setting up information about conditions, treatments, etc.
Configuring the menus for the particular type of clinic and the patient information that had to be recorded.
Configuring the reports to be generated by the system.
Configuring the rules that should be applied to the system data.

36. Issues and problems Objectives conflict
Management objective - provide reports against a set of headings defined by the Executive.
Clinical objectives - record patient information according to clinical classification.
Invalid configuration assumptions
The language for defining the rules of the system was not expressive enough to cover the requirements of Scots law regarding the forced detention of patients who were a danger to themselves or others.
Failure to configure the process
Local process differences meant that different clinics recorded different information about patients.

37. The C-b-C process for COTS
There is often no clear distinction between specification, design and development.
Systems are rarely completely configured before being put into use. The configuration process continues as the system is integrated with operational processes
There can be extensive (uncontrolled) “user” configuration of the system.
It is often necessary to configure the expectations of system stakeholders.

38. Process differences Two-stage system requirements process
Identify general requirements to chose a reusable system;
Identify specific requirements from settings where the system will be used.
Co-design of process and software
May be more active stakeholder involvement in the development process.
System testing is a problem.
Good practices such as configuration management, reviews, etc. are practically impossible to implement.

39. Choosing a COTS system
The decision on which COTS system to use is rarely a transparent process, based on a detailed analysis of the requirements in a specific setting.
Issues that affect the decision include:
Political issues;
Platform issues;
Cost and schedule issues;
Availability of expertise;
Prejudice!
The end result is often like the old joke where a man asks for directions to how to get to Dublin..
The response is ‘If you’re going to Dublin, then I wouldn’t start from here’.

40. Co-design
For C-b-C, separating requirements and development/deployment is unlikely to be successful.
Requirements compromises are essential because the stakeholder’s real needs need to be matched with what the system actually provides.
Configurability makes co-design, with stakeholder involvement in the design process, much easier.

41. System testing Testing is a particular problem for COTS-based systems.
Systems are not designed for running automated test suites.
There is no specification that can serve as a basis for deriving tests.
Problems that arise are often a consequence of interactions between the process of use and the system rather than system failure.

42. System evolution
Handover process from consultants to local IT staff. Change of system ‘ownership’
Limited expertise with system - may be managers rather than software engineers.
Problems of change management exacerbated because of the system configurability
Increasing system entropy as local configuration changes are implemented.
Evolution of underlying COTS system outside control of system owners.

43. Configuration problems
Understanding the configuration possibilities
Knowing what can be configured is not easy, especially if more than one product is included in the system
Understanding how to configure a system
Typically, configuration requires both business knowledge and technical knowledge
Predicting the consequences of configuration decisions
It is often difficult to understand how changing a configuration will affect the use and behaviour of a system while it is in operation
Understanding how a system is configured

44. Multiple configuration possibilities
Ways in which MS Word can be configured (that I’m aware of)
Preferences screen
Customisation screen
Organiser screen
Definition of templates
Definition of styles
Definition of macros
Inclusion of add-ins (e.g. Endnote)

45. Understanding how to configure

46. Configuration predictability
If you change a program, it is generally possible to hypothesise how this will affect the behaviour of the executing system.
When you change a configuration, the relationship is less obvious.
Change becomes a process of ad hoc experimentation. Gurus evolve who can suggest what to do but who can’t explain why it should be done that way.

47. Understanding the configuration
Once a system has been configured, how can others understand the configuration.
Requirements/design/code traceability is difficult enough in conventional systems but much harder in COTS where:
Requirements are not properly documented as a result of the co-design process;
Understanding requires knowledge of the COTS system + knowledge of the configuration.
Change costing and impact analysis is difficult
E.g. in the healthcare system we looked at, it was originally estimated that changing menus would take a few days. It ended up taking several months.

48. Challenges for C-b-C
Establish methods, tools and techniques for system engineering
Discover/establish general principles for designing systems for dependable configuration.
Define processes and standards for C-b-C
Design new methods and tools to support the processes of C-b-C.
Adapt supporting software engineering processes for C-b-C.

49. Principles
The diversity of different approaches to C-b-C mean that identifying unifying principles across different systems is very difficult
Possible examples of principles
Principle of visibility - make configurations explicit?
Principle of low coupling - reduce dependencies across configurations?
Principle of scalability - separate configuration of system deployment from configuration of functionality?
Principle of localisation - localise volatile configuration entities?

50. Methods, tools and techniques
Visualisation and analysis of configurations
There is a need for tools that allow engineers to see the ‘configuration state’ of a system and to explore dependencies across that state
Configuration policy description
There is a wide gap between organisational policy (esp. security policy) and the realisation of that policy as a configuration. Methods and tools are needed to bridge this gap and hence reduce configuration errors.

51. Processes for C-b-C Requirements engineering Design and implementation
Separation of the essential and the accidental
Essential elements used to select reusable systems
Accidental requirements subject to negotiation
This will clearly affect procurement processes.
Design and implementation
How can configuration ‘designs’ be modelled?
System testing
Testing against an incomplete spec. is difficult
How can test coverage be assessed?

52. Supporting processes
Users may be partly responsible for parts of the configuration process. This causes major problems with supporting processes
Configuration management
Existing tools are oriented to source code
Change management
Can users be stopped from making ad hoc changes?
Quality management
What does a ‘high-quality’ configuration mean?

53. Conclusions
Construction by configuration is a reality for modern business software development.
Political, technical and economic factors mean that this approach will be increasingly used for all types of system.
Our current ‘ad hoc’ approaches are not good enough - we need to adapt software engineering methods and techniques for this approach.

54. Key points
Reuse of COTS systems requires the business to adapt its requirements and processes to fit the assumptions in the system that is being reused
COTS solution systems are single domain specific or generic systems that are reused. Development involves configuration
COTS integrated systems involve several different COTS systems. Development involves both integration and configuration

55. Key points
Construction by configuration is an approach to software engineering that relies on configuring existing COTS systems
Existing software engineering methods have to be adapted for this approach to development
Key problems include visualising and analysing configurations, understanding configuration interactions and testing configured systems