Reference Information › User Interface Reference Guide › Graphical User Interface › Class Editor -- Simple Appliances › Interfaces Tab

Interfaces Tab

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Work with options in the Interfaces tab to define the network interfaces for the appliance.

There are two types of network interfaces:

• Terminals -- connects the appliance to other appliances
• External Interfaces -- interacts with entities outside of the application.

Most appliances should use only terminals for their interactions.

Interface Table

The appliance terminals are named network interfaces, through which the appliance interacts with other appliances in the same application. For input and output terminals, the terminal direction determines whether the appliance originates connections or accepts connections.

Looking from inside an appliance, the terminal is a host name visible only to that appliance instance. The terminal name of an input terminal can be used inside the appliance to set up a listening socket for accepting connections. The terminal name of an output terminal resolves to whatever appliance is connected to the output and can be used to establish connections to that appliance.

Each input terminal can have many appliances connected to it. Each output terminal can be connected only to a single appliance.

Name

Name of the terminal, representing the role of the interface within the appliance. It is a single word, case-sensitive, alphanumeric ([A-Za-z0-9_]). Terminal names are usually lowercase and short -- 3 to 4 characters, so that they fit in the appliance terminal shape.

Type

Type of the connection: input, output, or raw. The direction determines whether the appliance originates connections (client-side of most protocols) or accepts connections (server-side of most protocols). The direction determines only where the connection originates from; the appliance can pass data in and out of any terminal.

Protocol

Application-level (layer 7) protocol that will be used for connections on this terminal. Selecting the correct protocol allows the enforcement of aspects of the communication and, more importantly, to provide protocol-specific statistics, such as response time for the traffic passing through the terminal.

In case the appliance is protocol-agnostic, select Any in the drop-down list. The Any protocol also allows connections to be established from an output terminal to an input terminal (bi-directional terminals). To define new protocols, see the Protocols tab on the Application Configuration property sheet.

Alias

Alias of the terminal name used inside the appliance to refer to the terminal. The alias can be any valid DNS name (RFC 1035). That DNS name will be available inside the appliance as an alias to the terminal name. Aliases are useful when some application inside the appliance is hard-coded to access an external service via fixed host name (for example, server1.mycompany.com). The alias attribute is available only for output terminals.

Options

Optional terminal attributes that can be set on the terminal:

• The mandatory attribute marks the terminal as mandatory to connect for normal operation of the appliance. Typically inputs are non-mandatory and outputs are mandatory.
• The switch-sides button makes the terminal appear on the other side of the appliance shape. It is useful for feedback terminals whose connection direction goes opposite to the general left-to-right flow. This attribute affects only the visual appearance, it has no runtime impact.
• The gateway attribute makes an output terminal a default gateway interface for the appliance. A gateway output allows the appliance to access multiple hosts and resolve DNS names through that output. Typically, gateway outputs are used to connect appliances to the subnet gateway appliance ([GatewayOutNet][NET]]). Only one output of an appliance can be selected as a gateway. Most appliances don't have gateway outputs.
• The share attribute lets multiple terminals share one NIC. All terminals where the share attribute is set that belong to an appliance share a single network interface in the appliance's virtual machine. Since the number of interfaces and terminals an appliance can have is limited, this attribute is useful for decreasing the total number of interfaces an appliance uses.

Note: The share attribute cannot be specified on raw interfaces and should not be enabled for Windows appliances. It should not be set on appliances that need separate network traffic statistics. Appliances that provide network traffic statistics to the Monitor appliance provide only aggregated statistics for shared terminals.

The order of the terminals in the list, and in the appliance shape, can be modified by selecting a terminal entry in the list and using the up and down arrow buttons on the right side of the list. This is especially useful for appliances that have more than one terminal on one of the sides.

Important: If a mandatory terminal is not connected, the application will not start. This helps ensure that configuration constraints are met and prevents many configuration errors from happening. CA AppLogic® will report the name of the appliance and the terminal that failed the check to allow you to easily locate it.

Legacy Raw Interfaces

Applications created prior to CA AppLogic® 3.5 do not support multiple raw interfaces. For these applications, you could define a single raw interface, named external, which you could enable or disable. These options are retained for backward-compatibilty with applications created before CA AppLogic® 3.5.

External Interface

This option enables the appliance to interact with other applications and with any host accessible on the network (external interactions). In hosted CA AppLogic® environments, the external interface has access to the Internet, so verify the appliance is properly firewalled and otherwise protected if you enable the external interface. The appliance is responsible to fully configure the external interface, including its IP address, gateway, and so on. Typically, only gateway appliances need to have the external interface enabled.

Default Interface

This option allows the appliance to interface with the CA AppLogic® system, specifically permitting authorized secure shell (ssh) connections to the appliance.