New research from Forrester indicates that the global market for cloud computing will reach a whopping $241 billion by 2020, encompassing everything from software to cloud-based platforms.

The report, which is titled “Sizing the Cloud,” is touted by Forrester as the first industry research to wholly classify the growth of the market by sector and category, and to predict when those sectors will hit saturation and see commoditization, thus affecting the pricing of cloud-based services.

Based on a blog post about the report, the study is more about assigning specific definition to cloud sectors:

Cloud computing definitions are still a challenge. Virtualization technologies, management tools, and service provider industrialization have evolved continuously and at an amazing speed over the past five years. Each year, it gets harder to make clear-cut distinctions, based on technology, between what is a cloud and what is simply a virtualized data center or a traditional hosting provider.

Forrester used its taxonomy of 12 different market segments and business models to size the cloud market in an attempt to refine the definition of cloud services and various approaches to delivering them. From the perspective of IT professionals, the most interesting distinction the report makes is between opex and capex expenditures: Forrester defines a “pure opex model” for cloud computing as “the self-service consumption of highly standardized services via a pay-per-use payment model,” essentially saying that IT organizations have not invested an capex in the cloud—thus, more of a public cloud scenario. Private cloud deployment is defined as a capex investment by enterprises, and deemed more attractive to IT pros who want to know where their data is and have greater privacy requirements than a highly shared public cloud allows.

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Among the highlights of the report are that Forrester sees infrastructure-as-a-service shifting from a public cloud model to virtual private clouds, with increasing adoption of dynamic infrastructure services combined with high-level services and close integration into existing on-premises platforms. Platform-as-a-service, meanwhile, is predicted in the report to transform into middleware platform on which customized solutions can be created.