User can use Service Callbacks to add own custom scripts using C language based callback methods.

## Call Back Details

In call back details, the user has to fill the following details which are listed below :

- Use On Request Method : This method is called on receiving the service request and after all search and conditional parameters are processed and before applying service delay time.
- Use After Request Method : This method is called just before sending the response of the service.

Note : If a user wants to use their own library, then they have to click on the Use External Library checkbox in order to upload their own library and then click on the Add Upload Library Add Upload Library button to choose their library file. the files can either be selected from the drop-down list or the user can upload it from their system.

### Add API

An API is a software interface that allows two applications to interact with each other without any user intervention. On add API, there are following options available which the user has to select to add an API :

- Group : In the group, the user can select on which group the API is to be added. There are following three options which a user can select from the drop-down as follows:
  1. All : On selecting this option, the selected API will be added on the callbacks.
  2. Database : On selecting this option, the selected API will be added on all the Database groups.
  3. Utility : On selecting this option, the selected API will be added on the Utility groups.
- Sub-Group : In the sub-group, the user can select on which sub-groups the API is to be added. There are following three options which a user can select from the drop-down as follows:
  1. All : On selecting this option, the selected API will be added on all the sub-groups.
  2. ODBC : On selecting this option, the selected API will be added only on ODBC groups.
  3. String : On selecting this option, the user has to select the Source and the Destination of the string which is to be added.
- API : In this option, the user can select which API they want to pass for a particular Group and Sub-Group.
- Destination : In this field, the user has to enter the destination on which the API is to be added.
- Source : In this field, the user has to enter the source from where the API is to be added.
  Note : In case the source name is a program variable, then the user needs to select the If Source Name is a Program Variable checkbox.
- Length : In this option, the user has to enter the variable length.
- Return Variable : In this option, the user has to enter the return variable.
- Connection String : In this option, the user has to provide the connection string's name on which the information is stored.

### API Details

- In API Details, the user can see all the details which are being entered by them such as: Syntax, Description etc.
- In API details, the user can see the information for the following:
  1. Syntax : It will show the syntax of the API.
  2. Description : It will show the description of the syntax.
  3. Example : This field will show the example for the syntax.
  4. Parameterization : This field is used to parameterize the arguments which are passed in the function.
  5. Return : It will show the type of the variable which will be returned.

Note : The return variable and connection string is only applicable in case if the user selects Database in Group field and ODBC in Sub-Group field. Once the user has entered the values on all the fields, the user can add Add Upload Library the values on clicking the ADD button or can click on the Cancel Cancel button to cancel the entries. Once all the values have been entered by the user and also the API is being added, the user have to click on the Save Save button in order to save the call back details.