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Middleware is software that runs on content servers and within the operating systems of various types of set top box in order to provide a consistent authoring environment for content developers, often across an installed base of differing set top boxes. Accordingly Middleware manufacturers must account for a number of variables, the power of the set top boxes they wish to support, type of environment provided to programmers for content development enabled by this constraint, and the type of transport mechanism available within a given system.
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Generally speaking, set top boxes are divided into two classifications, thin clients such as the Motorola and SA 2000 series and thick clients such as the Motorola DCT 5xxx and SA 8xxx as well as the emerging home media center products.
Thin clients feature basic functionality, usually enough to handle basic EPG and VOD functions and have lower powered CPUs and less RAM. Because of these technical limitations, middleware on these platforms tend to be head end rendered or use low level code to get extra functionality out of the lower powered CPUs. However these units have a very wide installed base in cable systems, so a large portion of the industry is directed to serving them.
Thick client boxes, while less widely deployed are considerably more powerful in terms of RAM and CPU speed. This extra power enables additional functionality in the middleware such as support for a wider variety of content types and new media functionality such as Flash and advanced scripting. These units are also beginning to incorporate PVR (Personal video recorder, e.g. TiVo, ReplayTV) functionality, which will enable the next generation of interactive television applications.
Development environments enabled by middleware also vary from procedural environments which enable developers to write code directly to the middleware to declarative environments where HTML or a similar language is used to describe the layout which is then rendered by a browser or graphics engine incorporated in the middleware. In general, thin client boxes use a procedural environment which can best utilize their scarce resources, while thick client boxes have enough power and internal resources to render declarative content.
While this rule of thumb is generally accurate, rendering of content does not always take place on the set top box. The most common exception is the case of head end rendering. This approach allows for declarative content to be rendered at the cable head end and then sent to the set top box as an MPEG still. This still is sent either "out of band", using a separate carrier frequency from the main multiplexed programming feed, or in the case of recent digital systems within the digital program stream itself.
There are down sides to this scenario. In the case of out of band transmission, space on this carrier is finite and it is unclear what would happen in a situation where many competing programs are all carrying interactivity. In the case of digital delivery, arrangements for data carriage are at an early stage with the MSOs and it is unclear whether there will be a cost associated with it.
Listed below are most of the major players in middleware each with its own different approach to these issues. It is interesting to note that most of these companies have moved from providing just middleware to an end to end scenario, providing authoring tools, head end products as middleware.
Alticast
Alticast builds end to end interactive digital television systems with significant Asian deployment. Their middleware product "AltiCaptor" supports both the DVB-MHP and ATSC-DASE standards application and declarative environments through the AltiJVM Java virtual machine and the Altibrowser browser. Alticast also manufacturers the AltiComposer ITV authoring system and is one of the few manufacturers actively pursuing multiplatform support.
AOLTV
While this platform was officially discontinued in February of 2003, AOLTV remains one of the best platforms to gain experience in developing ITV applications. This is because all rendering is done on board, eliminating the need for expensive head end simulators and out of band modulators, and developer info has been, until recently at least, easily obtainable.
AOLTV is based on Liberate's analog "A" platform. While the level of HTML implementation is below ATVEF spec (3.2 vs. 4.0), it does support a number of functions not included in ATVEF, notably .WAV, .MIDI and a limited implementation of Flash 3.0. See AOLTV Authoring.
Canal Plus
Designed for next generation digital set top boxes, currently deployed in Europe, Canal Plus provides an end to end interactive television solution centered around their Mediahighway middleware product. Media highway 2.0, the current release, is said to support broadcast standards such as DVB, OpenCable, and ATSC, and applications written in formats supported by these standards such as Java, XDML and HTML.
Espial
Espial (pronounced "S P L") offers a suite of OS-independent applications for set-top boxes. These applications are built to support MHP, OCAP, ATVEF and other key standards. Another product is "Espial DeviceServer," which may be used at head-ends to provide value-added services.
Espial is a partner at the Java developer website Devicetop.com, where they offer support furums as well as trial sdks and simulators.
Liberate
Liberate is one of the few companies with significant US deployment with their TV Navigator product installed on several million set top boxes within the Comcast system. TV Navigator is available in four versions, the "S", "C", "M", & "A".
The "S" version is designed for high end set top boxes such as the Motorola DCT-5000 with digital television input and features full ATVEF compliant HTML support. The "C" or compact platform, which runs exclusively on the Motorola DCT-2000, is java based with rudimentary HTML support The "M" or Micro platform is a java based thin client offering designed to run on low end SA boxes. The "A" version is the platform for AOLTV and is no longer supported by Liberate.
See ITV Authoring for Liberate Platforms.
MSTV
MSTV is Microsoft's middleware which underlies a number of products, WebTV, WebTV plus, PersonalTV and UltimateTV. These products allowed Microsoft to take an early lead in ITV and if you can find them, WebTV Plus systems are among the best systems to learn about ITV application development on. WEBTV allows the user to surf the Internet on their computer, WEBTV plus adds ITV functionality, PersonalTV allows PVR functionality, and finally UltimateTV bundles all these with a satellite receiver. Unfortunately these products did not gain wide commercial acceptance and are all either discontinued or on their way out.
Of late Microsoft has been concentrating their efforts on a end to end solution with the MSTV server in the cable companies head end and a windows CE based middleware on the set top boxes. Included in this package are standard cable utilities such as an integrated EPG, and PPV and VOD support. The technology is said to be compliant with a wide variety of Broadcast standards such as ATSC, DVB and NTSC, and supports SMPTE 343 for interactive television, however it is unclear weather it supports the interactive layers contained in the ATSC and DVP standards.
It is important to note that Microsoft has a number of other products such as the Xbox, Media center, and its Windows operating system products, which either are or can support much of the ITV functionality traditionally supported on set top boxes. As such Microsoft is working to integrate these products into a cohesive whole.
NDS
NDS's middleware product, NDS Core is designed for the current generation of digital set-top boxes and has seen deployment in Latin America, Asia, and in Europe on the SkyTV system.. The basic version offers basic MSO services such as IPG and PPV and conditional access, while the more advanced version offers very high level HTML and Java support. NDS's Current deployments are based around the European DVB standard, however they seem very interested in the North American market, so an OCAP ATSC or NTSC version may not be far behind. Finally NDS is actively working in the area of IP based broadcasting which may give them a leg up on the emerging media center market.
OpenTV
Recently acquired by Liberty, and now a sister company to Wink and Ascent (formerly Liberty Livewire) OpenTV has a number of middleware products.
The OpenTV system, also known as EN, is a proprietary procedural environment based on the C programming language. It has seen wide deployment in Europe and has a number of specialized composition tools which allow content development by non-programmers.
The HTML based Device Mosaic system was obtained by OpenTV through their purchase of Spyglass and is advertised support all functionality specified in ATVEF 1.1 as well as HTML 4.01,SSL 3.0, and many aspects of CSS-2. There are a number of systems currently running this system, notably Cablevisions IO system on Sony set top boxes. It should be noted that the DM browser is sold as a commodity and while the original code as shipped from OpenTV is quite good, there is a great deal of customization done to it by the entities that license it, frequently causing erratic behavior.
Finally OpenTV's Prism system is an integrated (client and server) XML based system designed to distribute content across multiple platforms such as PDAs and cell phones as well as the set top box.
PowerTV
PowerTV is a subsidiary of STB manufacturer Scientific-Atlanta and its middleware product is installed in 4.6 million set-top boxes worldwide. PowerTV's OS, includes a middleware layer with an HTML 3.2 graphics engine and browser, and a C programming environment for developers who want to build applications in a low level procedural environment. In the past the browser, while part of the basic software package, has seen only limited implementation. However recently SA has been installing ATVEF-A compliant set top boxes on the NYC Cablevision system indicating integration of true interactivity into this product.
Wink
Recently acquired by Liberty, and now a sister company to OpenTV and Ascent (formerly Liberty Livewire) Wink is widely deployed (6 million homes) in both cable and satellite systems and is one of the few analog implementations of ATVEF-B. While there is said to be two versions, a proprietary thin client version and an ATVEF compliant version, as far as we know only the proprietary thin client version has seen any deployment. Because of its proprietary nature, this system is expensive to develop for and information on it, hard to come by.
Worldgate
Worldgate is proprietary head end rendered system whose functionality is designed to be integrated with products from a variety of other vendors notably TV guide IPG and Wink. Like many other players in the industry, they have refocused their business efforts, in this case towards licensing their existing technology and application development.
Revised Monday, 25-Aug-2003 14:06:01 CDT
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