Under the Hood
How does Presence work, and what can you do with it? Let's take a quick look at the underlying technology.
The Cisco Unified Presence Server (CUPS) is a Session Initiation Protocol (SIP) based technology that allows interaction with applications, endpoints, and other Presence-enabled environments (Cisco and, to a limited degree, non-Cisco). One of the first questions I get when starting any discussion of Presence is what OS it runs. The Cisco Unified Presence Server is an appliance model just like the Cisco Unified Communications Manager (CUCM).
The Presence engine collects information from numerous sources about individual users and their status in real time via SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE). This information also includes capabilities information, such as the user's ability to utilize voice, video, IM, or collaboration in his or her current environment. The information collected by the server is held in a user-specific repository within the Presence server and made available to applications interfacing with the server. Figure 2 shows the basic relationship between various endpoints, the CUCM cluster, and the Presence server.
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Figure 2 Cisco Unified Presence server sources and consumers.
Cluster Scaling
The Presence server has the ability to integrate with LDAP natively. This approach allows for importing of users into the server dynamically.
As with many Cisco Unified Communications (UC) components, Presence servers come in various sizes based on need and size of the deployment. Table 1 details the Presence user capacity for each platform.
Table 1 CUPS User Capacity by Platform
|
Server Platform |
Maximum Users |
|
MCS-7816 |
500 |
|
MCS-7825 |
1,000 |
|
MCS-7835 |
2,500 |
|
MCS-7845 |
5,000 |
Assuming the use of an MCS-7845 as the Presence server platform, up to 5,000 users can be supported on a single server. A secondary server can be added for redundancy. Additional servers or redundant pairs can be added to create a Presence cluster that can serve up to 30,000 users. This capability allows Presence to scale to the same top-end phone count as a CUCM cluster.
Cisco Unified Personal Communicator (CUPC)
Desktop clients represent one of the best means of leveraging the information made available by the Presence server and its information repository for each user. The primary client put forth by Cisco with this purpose in mind is the Cisco Unified Personal Communicator (CUPC). This client is available for both PC and Mac computers. In the discussions that follow, I'll utilize the PC version.
Figure 3 shows the primary CUPC client contact list interface. At first look, it seems very similar to an IM client. It has the same IM features as a typical IM client, but it also incorporates voicemail and phone logs (placed calls, received calls, missed calls) and provides for a directory search function from the primary interface. The phone logs are visible at the bottom of the figure and can be filtered using the drop-down list, which currently has View All selected.
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Figure 3 Cisco Unified Personal Communicator.
Multiple users are easily identified in the CUPC interface, and their current status is easy to ascertain: Red signifies unavailable, yellow signifies On the Phone, and green signifies that the user is available for contact. At the top of the interface are icons that will activate upon clicking a user's name. The capabilities information in the user repository shows which of the contact methods (phone, video, IM, email) are available for that user. There's also a dial-pad button, as the CUPC client replaces the Cisco IP Communicator as a softphone endpoint. In order to interact with an individual, you simply double-click the user's name. The default action on double-click is configurable in the client preference settings (I tend to leave mine set for instant messaging), with the following options available:
- Send an instant message
- Place a call
- Place a video call
- Send email
Figure 4 shows the IM screen that pops up on double-click of a user name in the contact list. In the figure, notice that the phone and email icons are blue, but the video icon is grayed out. The capability information in the repository doesn't show that I have video capabilities, because my camera isn't connected. If I connect my camera, the video icon will be activated.
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Figure 4 CUPC instant messaging window.
Once the IM has started, a simple click of one of the icons at the top will escalate the conversation accordingly. Clicking the phone icon will cause my phone (desk phone or softphone, depending on the mode I'm in) to go off-hook and dial the person with whom I'm chatting online. Likewise, clicking the video camera icon (when active) will cause the call to go through in a similar fashion and activate the video cameras on both endpoints. (The call recipient can choose to allow or deny video, perhaps based on hair and/or makeup status.) It's also possible to launch a collaborative MeetingPlace, MeetingPlace Express, or WebEx session from this same window, should it become necessary to share applications and/or desktops.
Double-clicking a contact isn't the only way to choose a means of interaction; there's always our old standby, the right-click. Figure 5 shows options available after right-clicking a contact.
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Figure 5 Right-click interaction.
Again, the capabilities information shows which options are available and which are not. Additional information is available via the Contact Details selection, which shows all information imported from the LDAP directory for this user. In many cases, this feature also has the ability to show the individual's picture if it has been added to the LDAP directory. Selecting the Edit Display Name option allows you to enter the contact's name manually. Otherwise, the contact's LDAP user name shows, rather than his or her first name/last name, and so on.
Among the more important features of the CUPC client is the Server Health page. The name is somewhat misleading, in that it really doesn't denote server health per se. Instead, it denotes the configuration status for the particular user in question. By clicking Help > Show Server Health, you can view relevant information regarding the CUPC client communication with the various UC components. Figure 6 shows an example of this function.
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Figure 6 Showing the server health.
As with most things in the networking world, green is good. Gray indicators denote an inactive option. Anywhere red is visible usually denotes a problem of some kind, whether in communication or configuration. Notice that the Softphone option in Figure 6 is green, while the Desk Phone option is gray. The CUPC client gives you the ability to run in either Desk Phone mode or Softphone mode. If you're at your desk, you can switch to Desk Phone mode and control your desk phone from the CUPC client. Anytime you opt to place a voice call to a contact on your list, your desk phone will go off-hook and dial. Obviously, in softphone mode, the Desk Phone will not be in contact with the CUPC client. That's the case in this screenshot. If I switch to Desk Phone mode, the Desk Phone indicator will go green, and the Softphone indicator will be grayed out.
This page shows the individual components along with somewhat meaningful messages concerning each. Evidently, I'm overdue for a password reset on my voicemail. It seems I've put it off too long again.