Analysis, Technology

Transparent, interoperable, secure: the Office Open XML file format

By Jianggan Li | 3 May 2007

Oliver Bell, Regional Technology Officer, Microsoft Asia, highlights the importance of choice and compatibility in achieving the maximum benefits through effective XML data representation.

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Office Open XML is a file format specification for the storage of electronic documents such as memos, reports, books, spreadsheets, charts, presentations and word processing documents.

“Open XML is a quite vibrant topic today,” comments Bell. “XML files allow users to be much more flexible in working with data stored in Office documents as well as developing applications around it.” Under Office Open XML specification, documents are saved in a zip package, with multiple XML files.

This creates unprecedented interoperability within an organisation or society. Any application that supports XML can access and work with data in the new file format, which implies that users can access Open XML documents on almost every platform in the world. They can also use standard transformations to extract or repurpose the data.

Transparent format “It’s really the customer demand that led Microsoft to look at contributing to the development of the Open XML specification in a serious way,” explains Bell. “Customers want their data to be interoperable, transparent and more secure.”

Binary files (.doc, .dot, .xls, and .ppt files), which for years did a great job of storing and transporting data, were not able to meet the new workplace challenges that included moving data between disparate applications, and allowing users to glean business insight from that data.

In response to these demands, Microsoft began experiments on XML as a future industry standard in 1997. The project of developing Open XML started in late 2000 and has been ongoing. With some simple XML implementations embedded in Office 2003, XML file format was introduced in a bigger way in the 2007 Microsoft Office system released earlier this year.

In the 2007 Microsoft Office system, every document saved is saved in an XML based format, regardless whether it’s Word or Excel or the other formats. “So you’ve got transparency on all the data for all the Office applications,” Bell comments. As an open standard, Office Open XML was standardised by Ecma International as Ecma 376 in December 2006 and is currently undergoing a standardisation process within ISO.

Backwards compatible Bell believes that the compatibility of the XML format with earlier versions of Office is equally important. In 2007 Microsoft Office system, although Open XML is the default format, the software version is able to read or write these binary files ‘just as they are’; and the binary files can then be saved into Open XML format directly through 2007 Microsoft Office system, or otherwise.

For earlier versions of Office, Microsoft released a free compatibility pack which allows earlier versions of Office to read and write Open XML format files transparently: “So there is no problem for users of those versions to read files from users who have chosen to upgrade,” assures Bell. “This is something that we are really proud of.”

The company has also sponsored an open source project which allows user to do conversion of Office documents between the OpenXML format and other formats such as ODF; this project is completed and is currently one of the most active projects on Sourceforge, an open source development site.

“We’ve done a lot work looking at what the customers want to do with the billions of documents around them today in binary document formats,” adds Bell. “This is really a good example of us committing lots of resources in response to customer demands.”

Government drivers Bell believes that there are three key benefits for governments with the Open XML file format –archiving information, enhancing citizen access and building richer government services.

“Governments need to be able to retain information for many years and retrieve when necessary. Microsoft is working with a number of governments in the region on archiving solutions,” he explains. “Traditionally governments save data in binary formats – it comes to a point where it is hard to get that data when the industry evolves from one proprietary binary format to another.”

Because the XML format is principally text based, government is able to save document files for many years to come: “Transparency and availability around legacy information and archiving within the government is significant,” he adds.

Because the Open XML file format is supported and implemented by a number of different software providers, governments accepting the Open XML format are able to serve users from a much wider variety of platforms than they would be able to do with earlier binary formats.

Moving forward, the Open XML format enables government developers to build a richer experience with solutions operating on an Office platform. They will be able to use XML for integration of legacy systems into new services that are being built. Users can embed customer data objects in an Open XML file, so the overall package doesn’t have to just contain the word document, they can also contain other things that are relevant to government process.

Secure and robust When a binary file comes to a security gateway, the system has to decide either to accept the file or reject it. “You either allow vulnerable files in or you keep everything out,” Bell notes. The industry has advanced forward in the last few years with the XML file format. Today, these concerns are reduced because the information is stored in XML, which is essentially plain text. And with a multi-part zip file, fire walls will be able to distinguish document from macros and live codes, and thus block the potential harmful part of the package while letting the essential data pass through without hindrance.

Open XML format also shows its robustness in its improved data recovery capability. This is achieved by segmenting and separately storing each part within the file package. When one file component is corrupt, the remainder of the file is still open within the application. This will entail lots of savings from data recovery costs in the context that data corruption is frequent with the prevalence of network transmission.

Open XML documents can also have digital signatures embedded that protect the entire document or any subset of the package parts. For example, you could sign a chart embedded in a word-processing document, ensuring the chart is tamper-proof but the rest editable. Documents can be signed manually through the Office UI, and Microsoft .NET Packaging API provides tools for developers to sign documents in their code.

As for encryption, the Open XML specification describes how a package can be encrypted and password-protected, and this has been implemented in Office. Within Office you can also plug in custom crypto providers to use your own encryption scheme, as is required by some intelligence agencies: Comments Bell. “You can now secure yourself more effectively around the XML format than you previously did with binary file format.”

Open market The Open XML format has been well received by the industry as well as the market. Customers today are able to decide on which formats will work best for them and their businesses. IT vendors today have shown tremendous support on file formats as evidenced by the growing ecosystem being built around them. Novell has support for OpenXML in Open Office. So does Dataviz for Palm OS.

Numerous projects revolving around Open XML have been initiated by Microsoft’s customers and partners, and the company recently signed a partnership with the Halal Industry Development Corporation (HDC), the company entrusted by the Malaysian Government to direct and co-ordinate the development of its halal industry, to develop the Malaysian Halal Hub Open XML System for the global market.

Added Bell “This is a good example how we use the technology to do some market activity that people would otherwise be closed in closed systems,”

Bell’s view was reinforced by Michael Mudd, Computing Technology Industry Association (CompTIA)’s Director of Public Policy, Asia – Pacific, “Competition among multiple open document standards will enhance innovation in document formats and increase flexibility and interoperability all to the benefit of software consumers. Where Open XML is concerned, it is an open standard that will be a key advancement to the ICT industry and provide critically needed choice in the document format space, allowing for greater vendor independence and reduced lock-in. This is because, as an open standard, Open XML ensures that digital content is more efficiently stored and managed today as well as into the future.”

While there are a few XML file formats out there in addition to Open XML, the emphasis here is not getting value from the document format itself, but ‘how government data should be represented in a document format’.

“It’s quite important that the market is open, and that people are given a choice to use a platform,” Bell notes. “Our vision for Open XML format is pretty clear. We are in the end a platform company; what we do is provide a platform that people can work with and build solutions on top of.”