Chapter 12 Interoperability with XMPP Systems Using the XMPP Gateway, Darmowe ebooki Microsoft, pobierz pdf

Introduction

The Microsoft® Office Communications Server 2007 R2 Extensible Messaging and Presence Protocol (XMPP) gateway enables Microsoft® Lync™ 2010 users to use instant messaging (IM) with and view presence of users who are using XMPP systems such as Google Talk and Jabber. This chapter focuses on ways to deploy, troubleshoot, and gain a deeper understanding of how the XMPP gateway functions. As of the publication of this chapter, the supported version of the XMPP gateway that works with Lync 2010 is the Office Communications Server 2007 R2 XMPP gateway. This chapter focuses on interoperability between Lync 2010 and this gateway.

XMPP is an XML-based protocol for exchanging messages in real time. It allows for users to exchange messages and presence. The major Request for Comments (RFCs) that define it are RFCs 3920 and 3921 (for details, see the “Additional Resources” section later in this chapter), although there are several other XMPP protocol-related RFCs.

The XMPP gateway converts SIP traffic from Microsoft® Lync™ Server 2010 to the XMPP protocol. It allows for IM and presence related communications between Lync users and users on XMPP services.

The XMPP gateway currently supports the following XMPP servers and services:

· Jabber Extensible Communications Platform (Jabber XCP 5.4)

· Gmail.com, googlemail.com, and other available Google Apps domains

Scenarios

To Lync users, adding an XMPP-based contact, viewing that contact’s presence, or exchanging IM with that contact is no different from using Lync to communicate with any other federated contact.

Note: IM and presence are the only supported modalities.

Adding a Contact

To add a contact, type the user name of the person you want to communicate with (for example, user1@gmail.com). When the user name appears in the search results, right-click the name, select Add to Contacts List, and then select the group where you want to place the user.

Figure 1. Adding an XMPP-based contact to the Contacts List

Updating Presence

When you change your presence information, XMPP contacts will see your status changes. You will also see your XMPP contacts’ status changes.

Figure 2. Changing presence status

Sending a Message

Sending a message to an XMPP contact is the same as sending one to other federated contacts. You double-click the contact to open up a Conversation window, type the message you want to send, and then press Enter.

Figure 3. Sending an XMPP contact an instant message

Internals

This section contains details of the protocol level traffic that occur between the Lync Edge Server and the XMPP gateway (SIP traffic) and the XMPP gateway and a third-party XMPP partner. The following diagram shows the two legs of traffic and the following details show the relevant protocol traffic that is sent over the wire.

Figure 4. Traffic flow reference

The areas we’ll focus on for traffic are:

· SIP traffic between the Lync Edge Server and the Office Communications Server 2007 R2 XMPP gateway

· XMPP traffic between the Office Communications Server 2007 R2 XMPP gateway and the XMPP partner third-party provider

There are three types of messages that can flow through the XMPP gateway:

· Contact additions

· Presence updates

· Sent messages

We’ll examine how the SIP and XMPP traffic for each of these transactions are translated by the XMPP gateway.

There are several limitations to the XMPP gateway that you should be aware of:

· Only one SIP domain is supported per deployment. This means that if the Lync deployment has multiple SIP domains there can be only one SIP domain that can federate through XMPP. This is a current limitation in the XMPP gateway.

· Enhanced presence is not shown on the XMPP network because there are differences between the implementations of presence and status indicators. For a full description of the mapping of presence states between Lync and XMPP, see Planning Deploying and Administering XMPP Gateway, which you can download with “Microsoft
Office Communications Server 2007 R2 XMPP Gateway” from http://go.microsoft.com/fwlink/?LinkId=220444.

· Lync Server 2010 cannot federate with an XMPP server with the same domain name. The SIP domain name and the XMPP domain name must be different. The following modalities, group IM, conferencing, and Enterprise Voice do not interoperate with XMPP by using the XMPP gateway. Only two-party IM and presence is supported with the XMPP gateway.

Capturing SIP and XMPP Traffic to and from The XMPP Gateway

There may be times when messages between Lync users and XMPP users fail, presence is inconsistent or failing, and the issue isn’t immediately presenting itself. In these cases it’s helpful to capture the SIP and XMPP traffic to find out where the issue lies. To capture the traffic sent across the XMPP gateway, do the following:

· To capture the SIP traffic between the Edge Server and the XMPP gateway, use OCSLogger on the Edge Server to collect SIPStack tracing, or use OCSLogger on the XMPP gateway to collect S4 tracing. After you’ve captured the SIP traffic, use Snooper to view the traffic. For details about how to collect logs on the XMPP gateway, see the “Troubleshooting” section later in this chapter.

· To view the XMPP traffic, use Network Monitor or another network monitoring tool (for example, WireShark) to capture the network trace of XMPP messages. The network trace is viewable only if you configure the TCP Dialback method with the federated XMPP server. For details about collecting and filtering network traces, see “Troubleshooting XMPP TCP Dialback Issues with the Communications Server XMPP Gateway” in the Office Communications Server 2007 R2 documentation, http://go.microsoft.com/fwlink/?LinkID=220272.

Adding an XMPP Contact and Subscribing to Presence

To add a contact or subscribe to a contact’s presence, the Lync client sends a SUBSCRIBE message by using the Session Initiation Protocol (SIP). SUBSCRIBE messages are used to subscribe to another user’s presence status. NOTIFY messages are then used to send the actual presence status after the SUBSCRIBE is successful.

The following is an example of a SUBSCRIBE message sent by the user, pkrebs@contoso.net, to the XMPP gateway ...

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