Creating a Cnxml File for a Custom Adapter

Create a cnxml configuration file for your custom external adapter so that you can configure the adapter in the ESP Studio, and start and stop it with an ESP project.

1. Specify attributes for the Adapter section:

   Attribute	Description
   type	(Required) Specify whether this is an input or output adapter.
   external	(Required) Set the value to true as this is an external adapter.
   id	(Required) Specify a unique identifier for your adapter. This value is listed in the type parameter within the ATTACH ADAPTER statement.
   label	(Required) The name of your adapter. This name displays in ESP Studio if you hover over the adapter icon in the Visual Editor.
   description	(Required) Specify the purpose of the adapter. This is also visible in ESP Studio.

2. Specify attributes for the Library section:

   Attribute	Description
   file	(Required) Specify "simple_ext" as the value. Always specify this for external adapters.
   type	(Required) Specify "binary" as the value.

3. Specify internal parameters for the Special section. See the $ESP_HOME/lib/adapters/simple_ext.cnxml.template sample cnxml file for a complete list of internal parameters and details on their usage.
4. Specify adapter parameters for the Section section. These parameters are visible and configuration in ESP Studio.
   For each parameter, specify:

   Parameter	Description
   id	(Required) The property id that you can reference to in <Internal> command calls with $(id's name). This is what you reference when specifying adapter properties for an adapter in CCL.
   label	(Required) The property name which appears in ESP Studio.
   descr	(Required) A description of the adapter property.
   type	(Required) The property datatype.
   use	(Required) Whether the property is required, optional, or advanced. In ESP Studio, required properties appear in red and advanced ones appear on a separate tab.
   default	(Optional) The default value to use, if you do not set a value for the property.

• Example Cnxml Configuration File
  Example of a cnxml configuration file that uses four of the utilities shipped with Event Stream Processor (esp_convert, esp_upload, esp_client, and esp_discxmlfiles) to fully define a functional external adapter that supports browsing a directory of files, the creation of a source stream, and data loading.
• External Adapter Properties
  See $ESP_HOME/lib/adapters/simple_ext.cnxml.template for a sample cnxml file that may be copied and customized. It has all possible internal parameters embedded in it, and has comment blocks indicating their usage.
• External Adapter Commands
  External adapter commands fall into two categories: those that run on the same host as Studio, and those that run on the same host as the Server.
• User-Defined Parameters and Parameter Substitution
  Internal parameters and any number of user-defined parameters can be created in the cnxml file.
• Auto-Generated Parameter Files
  The basic external adapter framework, when started, writes its set of parameters (system and user-defined) to a parameter file.
• configFilename Parameter
  The configFilename parameter enables you to specify user-editable configuration files in the Studio.