Thanks to a set of established Internet standards, groupware users can collaborate not only using a single groupware server—within a single organization, for example—but also to a certain extent with partners using different groupware clients and servers on Linux or Windows. This is done by sending email messages that contain the groupware information as attachments back and forth. All the available Linux groupware suites (Kontact, Evolution, and Mozilla) support this, as do proprietary clients on Windows and Mac OS such as MS Outlook or Lotus Notes.

As an example, let’s look at what ensues when you invite your friendly neighbor, who happens to still be running Windows and using MS Outlook, to your barbecue garden party on Wednesday. To do that you open your calendar to the current week and create a new event on Wednesday afternoon. (See Figure 8-46. We use Kontact in this example.) Add your neighbor as an attendee of the event and, since without him the party would be no fun, set his participation to be required. Once you’ve entered all the relevant information and closed the dialog, an email is constructed and sent to the email address of your neighbor. This message consists of a text part with the description of the event and an additional messsage part containing the details of the event in a certain format, which is specified in RFC 2446 and referred to as iTip.

Figure 8-46. Creating a new event in Kontact

At the receiving end, your neighbor’s Outlook mailer detects the incoming message as an invitation to an event and reads the relevant information from the attachments. One attachment asks your neighbor whether he’ll be able to attend and whether the invitation should be accepted, declined, or accepted tentatively. Since he’s not quite sure that Wednesday might be the night of a sports event he plans to watch, let’s say he chooses to accept the event tentatively. The event is then added to his own calendar inside Outlook and a reply message is constructed and sent, again containing a special iTip attachment.

Once that message makes it back to you, Kontact will inform you that the person you invited has tentatively accepted the invitation, and will enter that information into your calendar. As soon as your neighbor decides to either decline or accept the invitation, an update message will be sent and the status updated accordingly in your calendar upon receipt of that message. Should you decide to delete the event from your calendar, such an update message would in turn be sent to all attendees automatically.

The described mechanisms work not only for events, but also for assigning and sending tasks to other people and being informed when those tasks have been completed. To do that, you can add participants to tasks in Kontact’s Todo List view by right-clicking on a task, selecting Edit, and then opening the Attendees tab of the dialog that pops up. Of course, this functionality is also available in other clients, such as Evolution or Mozilla; the dialogs just look a bit different.

Similar to the iTip format (or iCal, which iTip is based on), there is an Internet standard for exchanging contact information called vCard. To communicate your new street address and phone number to your grandmother, who uses Mozilla on Windows for managing her many contacts, you could send her a message with your vCard attached (Figure 8-47). Using Kontact, this is as easy as right-clicking on your entry in the address book and selecting Send Contact. The resulting message should be easily understandable by most email programs on Windows, Linux, or the Mac. Most programs offer the user some convenient way to import the received vCard into his or her own address book. You can see how Kontact’s mail component presents such a message in Figure 8-48.

Figure 8-47. Sending your vCard

Figure 8-48. Receiving a vCard

As we have seen, it is quite possible to carry out basic group organization using only email mechanisms. This has two advantages: no groupware server is needed, and the operations work across different platforms and clients. On the other hand, things such as sharing a common calendar between several people or allowing read-only access to centrally managed information are not easily done with this scheme. This is where a groupware server starts to make sense.

Linux is supported as a platform by a wide range of groupware server solutions, including both open source projects and proprietary products. They all offer a core set of functionality for email, calendaring, and address and task management, but also contain various extensions for things such as resource management, time tracking, and even project planning. In general, these systems can be extended with custom components to offer functionality that is not provided by the standard package. Such components are sometimes available from the creators themselves, but are also often developed by third-party developers or as part of individual consulting projects.

The following sections describe the most well-known solutions available as free software at the time of this writing, with their respective focus areas and peculiarities.

One of the benefits of having information centrally stored and maintained is that changes and updates need only be done in one place and are then available to everyone immediately. This is especially important for contact information, which is prone to change and become out of date. The ability to quickly search through large amounts of contacts flexibly is another requirement that becomes more important the larger the organization gets, with all its internal and external communication partners. To meet this need, so-called directory services have been developed, along with a standard protocol to access and query them. The protocol is Lightweight Directory Access Protocol (LDAP), shared by a number of implementations, including the open source implementation OpenLDAP and (with typical Microsoft extensions) Microsoft Active Directory. OpenLDAP can be integrated with many of the groupware systems described in the previous sections.

The address book components of all major groupware suites allow the administrator to tie them to one or several LDAP servers, which are then queried for contact information and will be used for email autocompletion when composing emails. In Kontact, the LDAP configuration dialog for adding a new LDAP query host looks like Figure 8-49.

Specify the hostname of the server to be used for queries, the port it listens on (the default should be fine), and a so-called base DN, which is the place in the LDAP hierarchy where searches should start. The choice of base DN can help tailor the LDAP queries to the needs of your users. If, for example, your company has a global address book with subtrees for each of its five continental branches, you might prefer to search only your local branch instead of the full directory. Your site’s administrator should be able to tell you the values to be entered here. If the server only allows queries by authenticated users, enter your credentials as well.

Figure 8-49. Adding a new LDAP host in Kontact

With LDAP access set up, you can try opening up a mail composer in Kontact, for example, and typing someone’s name in the recipient field. After a second or so a list of possible matches that were found in the central LDAP addressbook should be shown. You can then simply select the one you were thinking of from the list. Additionally all groupware suites offer the ability to search for and display someone’s contact information, if you just want to look it up. In Kontact, the query dialog can be shown by clicking the LDAP Lookup button on the toolbar or from the Tools menu.