LiveView Query Input Adapter

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 field is set to Yes or a module parameter that evaluates to true, an instance of this adapter starts as part of the containing StreamBase Server. If this field is set to No or a module parameter that evaluates to false, 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 No or false, the adapter does not start even if the application as a whole is suspended and later resumed. The recommended setting is selected by default.

Enable Error Output Port: Select this check box 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.

This section describes the properties on the Adapter Properties tab in the Properties view for the LiveViewQuery adapter.

This tab allows you to configure a set of queries that will be registered each time the adapter connects to the configured LiveView server.

The tab has two columns, the first column is the key, or query ID, that identifies the query. This ID can be used in a delete command sent to the Query In port, for example.

The Value column has a semicolon separated string. The first part of the string is the select, projection expression for the query. For non-aggregate queries, this is usually just "*" - meaning provide all fields. The dynamic aggregation queries, this expression defines the aggregate functions and values to use. For example:

avg(lastSoldPrice) as AvgSoldPrice

The second part of the string is the query predicate. This predicate can include order by, time windows, group by, etc. where appropriate.

Use the Edit Schemas tab to specify the schema of the LiveView table this adapter will query.

For general instructions on using the Edit Schemas tab, see Defining Input Streams.

Use the Concurrency tab to specify parallel regions 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.

An optional QueryIn port is available. This port can be used to register and delete (unregister) queries to the LiveView server.

The StreamBase LiveView Query adapter has one output status port, plus two query out ports. The status port has the following fields:

The StreamBase LiveView Query adapter has a QueryOut port that has the results of all registered non-aggregate queries. The schema of this output has 6 fields, two of these are tuple types which simply have the schema configured in the schema tab.

The final output port is for Dynamic aggregation results. Since the input query selection expression defines the schema of the result, this variable output schema is represented in a JSON string. You can use StreamBase expression language functions, such as parsejson, to extra the values from these JSON strings.

Add an instance of the adapter to a new StreamBase EventFlow application as follows: