Communicator Web Access (2007 release) is an Office Communications Server 2007 server role that is now available on the Office Communications Server 2007 CD and no longer downloadable from the web. Communicator Web Access (CWA) addresses a specific customer need that is not satisfied by any other Office Communications Server 2007 server role.  CWA provides a server scale client for Office Communications Server that targets the following 3 platforms:

  • Locked-down Windows – these are IT administered Windows computers, and therefore users cannot install Office Communicator 2007 to sign-in to Office Communications Server. Such users can still sign-in to Office Communications Server via CWA.
  • Non-Windows platforms – computers not running a Windows operating system cannot install Office Communicator 2007. Such users can use CWA.
  • Mobile client platforms – mobile devices with web browsing capability and compatible with AJAX technology or a custom client can potentially sign-in to Office Communications Server using CWA. 

Communicator Web Access (2007 release) offers a zero install web client experience for Office Communications Server 2007 for those users who cannot use Office Communicator 2007. Users enabled for Office Communications must authenticate to CWA in order to sign-in to Office Communications Server (see Figure 1).  CWA supports 3 types of authentication methods: Integrated Windows Authentication, Forms-based Authentication, and Custom Authentication.

Figure 1

Because the UI similarities between CWA and Office Communicator are so close, CWA also makes for the perfect companion to Office Communicator because users do not need to adapt to a different user experience when switching between the two clients (see Figure 2).

Figure 2

Although CWA does not currently support VoIP functionality, users enabled for Enterprise Voice can get notified of incoming calls and redirect calls to a different number such as a cell phone.  Alternatively, users can configure to have incoming calls simultaneously ring a different number in addition to their work number or forward calls from their work number to a different number anywhere they can sign-in to Office Communications Server (see Figure 3).


Figure 3

For a comparison between Communicator Web Access (2007 release) and Office Communicator 2007, see table 2.


Table 1

In addition to offering a server-scale client solution out-of-the-box, CWA offers a cross-platform, cross-browser API set called, Unified Communications AJAX APIs, for the ISV community to integrate Unified Communications client functionality into web server applications such as web portals, line of business web applications, widgets and gadgets. This API makes it possible to create server-side Web 2.0 mashups.

The UC AJAX APIs are XML based.  This makes it very easy for developers familiar with XML but unfamiliar with the SIP and SIMPLE protocol, which Office Communications Server 2007 is based on, to quickly build Instant Messaging and Presence functionality into existing and new web applications.  CWA uses two secure connections (HTTPS) per client browser, one connection is used as the signaling channel to send requests to CWA, and the other connection is called the data channel used by CWA to send events to the client (see Figure 4).

Figure 4

With CWA’s Custom Authentication functionality, you can leverage Microsoft ISA Server 2006 to provide users a single sign-on experience (and avoid all those pesky logon requests) or enforce two-factor authentication access to Office Communications Server 2007 through custom development.

Microsoft makes available documentation and samples to help the ISV community build applications using the UC AJAX APIs.  Find out more and download the UC AJAX SDK at:


- Rui Maximo
Sr. Program Manager - OCS

Published Monday, November 12, 2007 11:27 AM by octeam
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