This document explains the Jabber Server, which functionality and characteristics it has, so everyone can get a better overview.
Jabber is an XML-based system for the near-real-time exchange of messages and presence.(A strong foundation in XML, which makes structured, intelligent messaging possible not only between human users but also between software applications.) Jabber uses a client-server architecture, not a client-to-client architecture. All Jabber messages and data from one client to another must go through the server. Any client is free to negotiate a direct connection to another client, but those connections are for application-specific usage only. There are even specific instances where this is encouraged, such as file transfers, but those instances are negotiated first within the context of a client-server framework. Jabber uses a distributed Network, its architecture is modeled after that of the e-mail system. Each user has their local server which receives information for them, and the servers transfer messages and presence information among themselves. There can exist any number of Jabber servers which accept connections from clients as well as communicate to other Jabber servers. Each server functions independently of the others, and maintains its own user list. Any Jabber server can talk to any other Jabber server that is accessable via the Internet. A particular user is associated with a specific server by a unique identefier (jid) that is like an emailadress.Jabber ID (jid)
Jabber IDs are used both externally and internally to express ownership or routing information. A Jabber ID is made up of a domain, node, and resource in the following format: user@host/resource or [node@]domain[/resource]. It is designed as a URI (Uniform Resource Identifier), a URI is a character string used to identify a resource (such as a file, in this case a session of a Jabber Server entity) from anywhere on the Internet by type and location. The term ’URL’ (Uniform Resource Locator) is a specific type of URI. For more information, visit http://www.w3.org/Addressing/.
The three main branches of the Jabber communication.-Info/Query: In the Jabber protocol, Info/Query is a data structure used to
obtain information about a Jabber Entity or to set information for an entity.
-Presence: Presence indicates whether a Jabber Entity is available for
communication. It includes basic Availability (i.e., online vs. offline), as
well as status indicators that capture various Availability Types.
-Message: A Message is used to transport information (a message) between two or more entitys
of a Jabber Server.
The Jabber Server is the software that connects and communicates with other Jabber clients and servers. All communications for a client are directed to the server and then passed to the client. All client preferences and data are stored on the server. The Jabber server plays two primary roles: 1. Listening for client connections and communicating directly with client applications. 2. Communicating with other Jabber servers. The Jabber Server is designed to be modular, it can be extended by modules (JSM) that implement speciale purposes, or comunicat with other deamons that register them selfs at the Jabber core Server (not like then the modules, they are not a part of it) , and translate the Jabber native protocol to a protocol of any other IM Service. This protocol translation deamons are called Transports, the comunication between a Transport and the core Server is based on Networkprotokols such as TCP/IP and can be hosted on diferent Servers.The Jabber core Server can be configured in one config file that is loaded into the Jabber core Server, it determines what modules of the JSM and what Transports should be loaded (on start up) along with detailed configuration information for each.
TransportA component of the Jabber server that provides a bridge over the Internet or a network, between the Jabber Server and any non-Jabber system or network. How is it doing that: -Protocol A protocol is a formalized set of instructions that developers follow when creating applications, including Jabber applications. -Native Protocol A native protocol is the format in which communications occur within a particular service. For example, the AIM Transport communicates with AIM by translating Jabber’s native XML protocol into AIM’s native protocol and vice-versa.
Client
-Resource: The resource of a Jabber ID can provide additional information
about how a user is accessing a Jabber server. A Resource can be the location
from which a user is connecting (e.g., home or work), the type of device a user
is connecting with (e.g., notebook or handheld), or the user’s specific Jabber
Client (e.g., JIM or WinJab).
-Priority: Priority is a user-defined setting that
determines the importance of each Resource a Jabber user is using to access the
Jabber server. The server will send messages and presence information to the
highest-priority resource, which is known as the Primary Resource. This enables
a user to connect to the server from multiple locations or devices, but only
receive messages at a single device or location.
-Roster: A list of Jabber Users or other Jabber Entities to whom a
Jabber User is subscribed. A user’s roster is often the combination of a
user’s Personal Groups and Shared Groups. -Subscription: A subscription is a
request to receive presence updates from a Jabber User or other Jabber Entity.
The receiving entity may refuse a subscription, preventing the requesting party
from seeing presence updates. If the receiving entity approves the subscription,
the requesting party will see presence updates.
Important:
The OACS Jabber server acts as one buddy, so if you send a message the receiver
of the message will think that the user "OACS" send him this message. Of course we want the receiver
to know who send him the message, so we append on every message your name at the beginning. Furthermore
the receiver cannot send you messages back if you send him the message via Webpages, because this way you would
be the OACS-user and not you!Therefore it is impossible for the Jabber server to track the messages and find
the original sender. So if you want to be recognized perfectly by the receiver and be able to receive messages aswell,
you have to send your messages through the Jabber Applet, because this Jabber Applet acts like a normal Jabber Client
and you would not send your messages via the Jabber server as general OACS-user, but as Jabber user with his own JabberID.
Author: Bjoern Kiesbye