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Chapter 3 • Enterprise Systems Architecture 83

system. Changing the database similarly and what information and services will be
will not affect the other layers. This can provided by the provider. This is similar to
lower maintenance and future upgrading object-oriented system architectures with a
costs of the system. higher degree of separation with a clear
•There are various types of layered architec- communications agreement between the
tures. The simplest and somewhat obsolete two objects. SOA benefits include faster
is a two-tier architecture, but it has limita- application development and reuse of soft-
tions (e.g., it supports only a small number ware modules. Major ERP vendors are now
of users and is not flexible for new versions supporting SOA in their newer versions of
of ERP software). Three-tier architectures their software.
separate application from the presentation •Management should not leave the enterprise
layer, thereby increasing the flexibility and systems architecture decisions to the IT
scalability of the system. ERP systems cur- department. ERP architecture is quintessen-
rently have expanded to Web-based archi- tial to a successful integration and implemen-
tectures to facilitate better integration with tation of an ERP system, and it has a wide
the Internet technologies. and long-lasting implication on the organiza-
•Another architecture that is gaining popu- tion. Top management must therefore be
larity is service-oriented architecture. SOA involved in designing the architecture from
separates the service provider from the the very beginning of the ERP implementa-
service consumer by making them sign a tion project. ERP systems embed organiza-
service-level agreement contract that speci- tional policy and are costly to implement, so
fies how the consumer requests the service any errors can bring down the organization.

Exercises

1. Search the Internet for SOA support from the three b. Find out how the architecture helped them in
major ERP vendors: SAP, Oracle, and Microsoft the ERP implementation.
Dynamics. Compare the SOA features in a table c. Does their ERP implementation support Web
format. integration and SOA?
2. Locate a company that you know and contact the d. Write a one-page summary and include a
IT manager and the HR manager. diagram or figure of their architecture.
a. Find out what ERP or enterprise architecture
they have in their company.

Review Questions

1. What is necessary for the ERP implementation to 6. Discuss the different types of ERP architectures.
be successful? 7. List benefits and limitations of one ERP architecture.
2. What is ERP system architecture? 8. What is service-oriented architecture and how is it
3. Why is it important to have good enterprise system different from Web services architecture?
architecture? 9. What are the key benefits and limitations of
4. What is the role of architecture in ERP imple- systems integration?
mentation? 10. What is the role of management in designing enter-
5. List five of the major functional modules of ERP. prise systems integration?