What Is The Cloud Storage Partner Program Plus?

The Cloud Storage Partner Program Plus (CSPP Plus) is an advanced program for larger organisations to implement the WOPI protocol. The basic Cloud Storage Partner Program provides a method (WOPI) by which third-party software vendors can incorporate Microsoft Office into their web-based applications. CSPP Plus extends this basic WOPI capability with a range of new features.

New Features of the Cloud Storage Partner Program Plus


Geo-Fencing is the ability to restrict the storage of WOPI files to specific regional data centres. In standard WOPI, the Office documents being edited can be hosted anywhere in the world, and the host cannot control this. With CSPP Plus, the host can specify per file (using the new ComplianceDomainPrefix property of CheckFileInfo) which single region the file should be stored in by Microsoft. The available regions are:

  • United Arab Emirates
  • Australia
  • Brazil
  • Canada
  • Switzerland
  • Germany
  • Europe
  • France
  • India
  • Japan
  • Korea
  • Norway
  • Singapore
  • United Kingdom
  • United States of America
  • South Africa

This will be a very useful feature for organisations implementing WOPI with specific compliance requirements (e.g. healthcare data) that prevent that data from leaving the country.

Desktop MS Office Integration

A huge new feature in CSPP Plus is that organisations can now add their own storage location to the “backstage” area (the bit you see when you open Office without a document) of MS Office and allow users to open Office documents from there using the WOPI protocol. It is unclear from the early documentation how this will integrate with the web editing experience, but we are hopeful that there could be a seamless editing experience.

Optimised File Transfer

CSPP Plus includes an extensive new file transfer system that will allow larger Office documents to be transferred in “chunks”. The new mechanism is complex and not for the fainthearted, but it will allow the WOPI client at the Microsoft side to request specific chunks of a file rather than the whole file to keep things in sync. This will be particularly important given Microsoft’s new support for larger Office document file sizes.

Additional Locking and Versioning System

The features explained here all introduce newer, more complex locking requirements. These are in addition to the standard CSPP Locks and Versions. A new Sequence number is required for CSPP Plus files, and a new Coauth Lock system has been created too.

Additional Program Requirements

CSPP Plus is a program for large organisations. Microsoft has not yet publicly released all of the entry requirements for the program, but we do know the minimum requirements:

  • You must already be a member of CSPP
  • You must pay a non-refundable entry fee (amount undisclosed)
  • You must be properly insured, including:
    • Commercial General Liability
    • Privacy And Cyber Security
    • Professional Liability
    • Errors And Omissions Insurance
    • Works Compensation
    • Employer’s Liability
  • ISO-27001 Certification
  • Microsoft 365 App Certification

Most organisations considering CSPP Plus will have no problems with the requirements above, other than possibly the ISO-27001 certification and the entry fee if it is significant.

Other features

Other features that are included are:

  • Access to FedRamp
  • Mobile MS Office integration (planned)
  • Intune mobile provisioning of storage locations
  • Invitations to the CSPP Plus partner summit

For more information on this topic, including troubleshooting WOPI API and verifying WOPI protocols using proof keys, look at our blog. If you are interested in learning more about the Cloud Storage Partner Program Plus, please don’t hesitate to get in touch with us at McKenna Consultants.

Nick McKenna
Since 2004, Nick McKenna, BSc, MBCS Biography has been the CEO of McKenna Consultants. McKenna Consultants is a bespoke software development based in North Yorkshire, specialising in Cloud development, mobile App development, progressive web App development, systems integration and the Internet of Things development. Nick also holds a First Class Degree in Computer Science (BSc) and wrote his first computer program at the age of nine, on a BBC Micro Model B computer. For the last 21 years, Nick has been a professional computer programmer and software architecture. Nick’s technical expertise includes; Net Core, C#, Microsoft Azure, Asp.Net, RESTful web services, eProcurement, Swift, iOS mobile development, Java, Android mobile development, C++, Internet Of Things and more. In addition, Nick is experienced in Agile coaching, training and consultancy, applying modern Agile management techniques to marketing and running McKenna Consultants, as well as the development of software for clients. Nick is a Certified Enterprise Coach (Scrum Alliance), SAFe Program Consultant (SAI), Certified LeSS Practitioner (LeSS) and Certified Scrum@Scale Practitioner. Outside the office, Nick is a professional scuba diver and he holds the rank of Black Belt 5th Dan in Karate.