# RXS_StartComposeEngine()

This subprocedure initializes the compose engine with a specific template file. This is utilized primarily to build XML but could be used to build any type of character data.

## Subprocedure Prototype

### IBM i 6.1+

| Field | Description |
|---|---|
| `     D RXS_StartComposeEngine...      D                 PR                  Extproc('RXS_StartComposeEngine')      D                                     Opdesc` |  |
| `     D   ComposeDS                         Likeds(RXS_ComposeDS_t)      D                                     Options(*Varsize)` | Pass in an RXS_ComposeDS_t to control how the composition engine functions. |


## Example Code

### IBM i 6.1+

#### Example 1
```rpgle
      *--------------------------------------------------------------
      * This example code initializes the composition engine for the EXAMPLE template and 
      *  configures it with the procedure address for the Template procedure.
      *--------------------------------------------------------------
     H DFTACTGRP(*NO) BNDDIR('RXSBND') ACTGRP(*CALLER)

      /copy QRPGLECPY,RXSCB
      /copy QRPGLETPL,EXAMPLE

     D ComposeDS       DS                  LikeDS(RXS_ComposeDS_t)
     D                                     Inz(*LikeDS) 
      /free
       reset ComposeDS;
       ComposeDS.TemplateProcedure = %Paddr(Template);
       RXS_StartComposeEngine( ComposeDS );

       *INLR = *ON;
      /end-free

     P Template        B
     D                 PI
     D  p                                  Like(RXS_TEMPLATE_PARM)
      /copy QRPGLETPL,EXAMPLE
     P                 E
```

## Data Structures

### RXS_ComposeDS_t

| Field | Description |
|---|---|
| `     D RXS_ComposeDS_t...      D                 DS                  Qualified Template Inz` |  |
| `     D   ReturnedErrorInfo...      D                                     Like(RXS_ReturnedErrorInfoDS_t) Inz` |  |
| `     D   OnErrorMessageType...      D                                5I 0` |  |
| `     D   TemplateProcedure...      D                                 *   Procptr` | Pointer to the address of the subprocedure that will compose the XML or other character based content. |
| `     D   LogFile                           Like(RXS_Var1Kv_t)` | IFS location where a log file will be created during composition. |