Contents
The Log output adapter is an embedded adapter that sends its input tuples to both its output port and to the StreamBase Java logging system, which is described in Using StreamBase Logging. Think of the Log adapter as a T-joint adapter, which passes its input unchanged to its output port, but also sends a copy of each input tuple to the logging system.
An instance of the Log adapter has a single input port and a single output port. This is a pass-through adapter, so the schema of the output port is always the same as the schema of the input port.
Name: Use this field to specify or change the component's name, which must be unique in the application. The name must contain only alphabetic characters, numbers, and underscores, and no hyphens or other special characters. The first character must be alphabetic or an underscore.
Adapter Name: A read-only field that shows the formal name of the adapter.
Class: A field that shows the fully qualified class name that implements the functionality of this adapter. Use this class name when loading the adapter in StreamSQL programs with the APPLY JAVA statement. You can right-click this field and select Copy from the context menu to place the full class name in the system clipboard.
Start with application: If this checkbox is enabled, an instance of this adapter starts as part of the containing StreamBase Server. If disabled, the adapter is loaded with the server, but does not start until you send an sbadmin resume command, or start the component with StreamBase Manager. With this option disabled, the adapter does not start even if the application as a whole is suspended and later resumed. The default and recommended setting is enabled.
Enable Error Output Port: Check this checkbox to add an Error Port to this component. In the EventFlow canvas, the Error Port shows as a red output port, always the last port for the component. See Using Error Ports and Error Streams to learn about Error Ports.
Description: Optionally enter text to briefly describe the component's purpose and function. In the EventFlow canvas, you can see the description by pressing Ctrl while the component's tooltip is displayed.
The Log adapter has the following properties on the Adapter Settings tab in its Properties View in StreamBase Studio:
| Property | Data Type | Description |
|---|---|---|
| Log level | pulldown list | Specify the type of logging message you want to send to the logging system from this adapter. The choices are to send INFO, WARN, DEBUG, or TRACE log messages. |
| Message Identifier | string | The specified string is prepended to the log message for each tuple. You can use this feature with several instances of the Log adapter to prefix different strings to the log messages from different portions of your application. This would make the application's log file searchable for different logging messages from each application section. |
Use the Concurrency tab to specify separate threading for this instance of this component, or multiplicity options, or both. The Concurrency tab settings are described in Concurrency Options, and dispatch styles are described in Dispatch Styles.
Caution
Concurrency settings are not suitable for every application, and using these settings requires a thorough analysis of your application. For details, see Execution Order and Concurrency, which includes important guidelines for using the concurrency options.
Typechecking detects a value for the output that is null or unspecified.