About the Airline Reservations sample

The Airline Reservations sample is based on the scenario of an airline reservation system like those used in travel agents. It demonstrates how to use some of the features provided by IBM Integration Bus.

The Airline Reservations sample demonstrates how you can design applications that process self-defining XML messages. XML messages are self-defining because each piece of data is prefixed by a tag name or an attribute name. An XML message definition is in the message itself and is not held anywhere else. Therefore, you can run a message flow that uses an XML message without the aid of an external message set.

If you use self-defining XML messages, you can program the message flow to manipulate messages, as you can if you use an external message set to hold message format information. However, without a message set, you must code all the format information in ESQL in the nodes of the message flow, and you cannot use the full range of built-in nodes.

The Airline Reservations sample performs the following actions:

• Reserves seats that are listed in the input message, and updates the user database to show that seats have been reserved and that there are now fewer seats available.
• Generates reply messages to confirm that the seats have been reserved.
• Retrieves information about the reservations that have been made, and outputs a message containing the information.
• Requests and retrieves information about the flights and the passengers who have reserved seats on the flights, and outputs a reply message containing the information.
• Cancels the reservations listed in the input message, and updates the user database to show that there are now fewer seats reserved and more seats available on the flights.

The following sections describe the Airline Reservations sample in more detail:

• The message flows
• The messages
• The database
• The WebSphere MQ queues

The message flows

The Airline Reservations sample includes the following message flows:

• XML_Reservation reserves the seats listed in the XML_Reservation input messages, see About the XML_Reservation message flow.
• XML_PassengerQuery dynamically routes the message and retrieves information about the reservations that have been made, see About the XML_PassengerQuery message flow.
• XML_FlightQueryOut, the aggregation fan-out flow in XML_FlightQuery, retrieves information about a flight and the reservations that have been made on the flight, see About the XML_FlightQueryOut message flow.
• XML_FlightQueryReply, the aggregation reply flow in XML_FlightQuery, retrieves information about a flight and the reservations that have been made on the flight, see About the XML_FlightQueryReply message flow.
• XML_FlightQueryIn, the aggregation fan-in flow in XML_FlightQuery, retrieves information about a flight and the reservations that have been made on the flight, see About the XML_FlightQueryIn message flow.
• XML_CancelReservation cancels the reservations that are listed in the input message, see About the XML_CancelReservation message flow.

Note that, at run time, the XML_FlightQueryOut, XML_FlightQueryReply, and XML_FlightQueryIn message flows function as a single message flow, which is referred to in this documentation as the XML_FlightQuery message flow.

For more information, see Message flows overview in the IBM Integration Bus documentation.

The messages

The Airline Reservations sample processes self-defining, or generic, XML messages. A self-defining XML message carries the information about its content and structure within the message in the form of a document that adheres to the XML specification. A definition of the message is not held anywhere else. When the message flow receives the message, the message is identified by the generic XML parser (XMLNSC), and the message is parsed according to the XML definitions contained within the message itself.

Six self-defining XML input messages are supplied so that you can run the message flows in the Airline Reservations sample:

• Two XML_Reservation input messages: The first message requests four seats on a flight, two in first class and two in economy class. The second message requests an additional seat, on a different flight, for one of the passengers, see About the XML_Reservation input messages.
• Two XML_PassengerQuery input messages: The first message requests information about all the reservations made by a specific passenger. The second message requests information about a specific reservation, see About the XML_PassengerQuery input messages.
• One XML_FlightQuery input message: The message requests information about a specific flight and a list of passengers who have reservations on that flight, see About the XML_FlightQuery input message.
• One XML_CancelReservation input message: The message requests that a list of reservations are canceled, see About the XML_CancelReservation input message.

The database

The Airline Reservations sample has one database called RESERVDB. The message flows in the sample directly access RESERVDB, which contains two database tables called XMLFLIGHTTB and XMLPASSENGERTB. For more information about the database in the Airline Reservations sample, see About the RESERVDB database.

Note that the Airline Reservations sample is driven at its inputs and outputs. In between the inputs and outputs are database interactions, which makes the sample a slightly unusual application. In most IBM Integration Bus applications the true application data is contained in external databases because IBM Integration Bus is typically the integration middleware between a client and a back-end database (which is often found on an existing server platform).

This unusual application does not detract from the usefulness of the sample. If you want, you can remove the database and make it external. Every message flow must then be split in two:

• The first part prepares queries and sends them out as messages. You then require a WebSphere MQ or a WebSphereadapter at the database server to enable the message to access the back-end databases.
• The second part catches the response from the back-end databases by using its adapter and returns a response to the requester (client).

If done carefully, such a system is indistinguishable (to the client) from the samples as supplied here, in which database access is internal.

The WebSphere MQ queues

The Airline Reservations sample message flows interact with WebSphere MQ local queues. The queues are defined on the WebSphere MQ queue manager that hosts the broker on which the message flow runs. For more information about the WebSphere MQ queues in the Airline Reservations sample, see About the WebSphere MQ queues.

Back to sample home