# Creating Function Groups with Low-Level Handlers
This guide demonstrates how to create a function group and add function modules using low-level MCP handlers.
## Overview
Function groups require a slightly different workflow than classes:
```
GetSession → ValidateFunctionGroup → CreateFunctionGroup → LockFunctionGroup →
CreateFunctionModule → UpdateFunctionModule → UnlockFunctionGroup → ActivateFunctionGroup
```
**Note**: Function groups cannot be updated directly - you add function modules to them instead.
## Step-by-Step Workflow
### Step 1: Get Session
Obtain a session ID and session state.
**Tool**: `GetSession`
**Request**:
```json
{
"force_new": false
}
```
**Response**:
```json
{
"success": true,
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "SAP_SESSIONID_E19_100=xyz...",
"csrf_token": "AbCdEf123456",
"cookie_store": {}
}
}
```
---
### Step 2: Validate Function Group Name
Check if the function group name is valid and available.
**Tool**: `ValidateFunctionGroupLow`
**Request**:
```json
{
"function_group_name": "ZFG_MY_GROUP",
"package_name": "ZOK_LOCAL",
"description": "Test function group",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response** (Success):
```json
{
"success": true,
"function_group_name": "ZFG_MY_GROUP",
"validation_result": {
"valid": true
},
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
---
### Step 3: Create Function Group
Create the function group structure.
**Tool**: `CreateFunctionGroupLow`
**Request**:
```json
{
"function_group_name": "ZFG_MY_GROUP",
"description": "Test function group for demonstration",
"package_name": "ZOK_LOCAL",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_group_name": "ZFG_MY_GROUP",
"package_name": "ZOK_LOCAL",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
},
"message": "Function group ZFG_MY_GROUP created successfully..."
}
```
**Note**: Function groups are created empty. You add function modules to them in the next steps.
---
### Step 4: Lock Function Group
Acquire an exclusive lock on the function group.
**Tool**: `LockFunctionGroupLow`
**Request**:
```json
{
"function_group_name": "ZFG_MY_GROUP",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_group_name": "ZFG_MY_GROUP",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"lock_handle": "BD53F3688D0F164CA3ADF06FD43C39E1CC1C3B32",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**CRITICAL**:
- Save `lock_handle` - it's required for Unlock operation
- **Save `session_id` and `session_state` from this response** - they MUST be used in Unlock operation
- **Lock and Unlock MUST use the same session** - use the `session_id` and `session_state` from this Lock response
---
### Step 5: Create Function Module
Create a function module within the locked function group.
**Tool**: `CreateFunctionModuleLow`
**Request**:
```json
{
"function_module_name": "ZFM_TEST_FUNCTION",
"function_group_name": "ZFG_MY_GROUP",
"description": "Test function module",
"package_name": "ZOK_LOCAL",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_module_name": "ZFM_TEST_FUNCTION",
"function_group_name": "ZFG_MY_GROUP",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
},
"message": "Function module ZFM_TEST_FUNCTION created successfully..."
}
```
---
### Step 6: Lock Function Module
Lock the function module to add source code.
**Tool**: `LockFunctionModuleLow`
**Request**:
```json
{
"function_module_name": "ZFM_TEST_FUNCTION",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_module_name": "ZFM_TEST_FUNCTION",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"lock_handle": "A1B2C3D4E5F6789012345678901234567890ABCD",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**CRITICAL**:
- Function modules have their own lock handle, separate from the function group lock
- **Save `session_id` and `session_state` from this response** - they MUST be used in Update and Unlock operations for this function module
- **Lock, Update, and Unlock for function module MUST use the same session** - use the `session_id` and `session_state` from this Lock response
---
### Step 7: Update Function Module
Add source code to the function module.
**Tool**: `UpdateFunctionModuleLow`
**Request**:
```json
{
"function_module_name": "ZFM_TEST_FUNCTION",
"source_code": "FUNCTION zfm_test_function.\n*\"----------------------------------------------------------------------\n*\"*\"Local Interface:\n*\" IMPORTING\n*\" VALUE(IV_INPUT) TYPE STRING\n*\" EXPORTING\n*\" VALUE(EV_OUTPUT) TYPE STRING\n*\"----------------------------------------------------------------------\n\n ev_output = |Hello from { iv_input }|.\n\nENDFUNCTION.",
"lock_handle": "A1B2C3D4E5F6789012345678901234567890ABCD",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_module_name": "ZFM_TEST_FUNCTION",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
},
"message": "Function module ZFM_TEST_FUNCTION updated successfully..."
}
```
---
### Step 8: Unlock Function Module
Release the lock on the function module.
**Tool**: `UnlockFunctionModuleLow`
**Request**:
```json
{
"function_module_name": "ZFM_TEST_FUNCTION",
"lock_handle": "A1B2C3D4E5F6789012345678901234567890ABCD",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
---
### Step 9: Unlock Function Group
Release the lock on the function group.
**Tool**: `UnlockFunctionGroupLow`
**Request**:
```json
{
"function_group_name": "ZFG_MY_GROUP",
"lock_handle": "BD53F3688D0F164CA3ADF06FD43C39E1CC1C3B32",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
---
### Step 10: Activate Function Group
Activate the function group (this also activates all function modules within it).
**Tool**: `ActivateFunctionGroupLow`
**Request**:
```json
{
"function_group_name": "ZFG_MY_GROUP",
"session_id": "a1b2c3d4e5f6789012345678901234567890abcd",
"session_state": {
"cookies": "...",
"csrf_token": "...",
"cookie_store": {}
}
}
```
**Response**:
```json
{
"success": true,
"function_group_name": "ZFG_MY_GROUP",
"activation_result": {
"status": "success",
"warnings": [],
"errors": []
},
"message": "Function group ZFG_MY_GROUP activated successfully"
}
```
---
## Complete Example
```python
# Step 1: Get Session
session = get_session()
session_id = session["session_id"]
session_state = session["session_state"]
try:
# Step 2: Validate Function Group
validation = validate_function_group(
function_group_name="ZFG_MY_GROUP",
package_name="ZOK_LOCAL",
session_id=session_id,
session_state=session_state
)
if not validation["validation_result"]["valid"]:
raise Error(f"Validation failed: {validation['validation_result']['message']}")
session_state = validation["session_state"]
# Step 3: Create Function Group
create_result = create_function_group(
function_group_name="ZFG_MY_GROUP",
description="Test function group",
package_name="ZOK_LOCAL",
session_id=session_id,
session_state=session_state
)
session_state = create_result["session_state"]
# Step 4: Lock Function Group
lock_result = lock_function_group(
function_group_name="ZFG_MY_GROUP",
session_id=session_id,
session_state=session_state
)
fg_lock_handle = lock_result["lock_handle"]
# CRITICAL: Save session_id and session_state from Lock response
# These MUST be used in Unlock operation
fg_lock_session_id = lock_result["session_id"]
fg_lock_session_state = lock_result["session_state"]
try:
# Step 5: Create Function Module
fm_create_result = create_function_module(
function_module_name="ZFM_TEST_FUNCTION",
function_group_name="ZFG_MY_GROUP",
description="Test function module",
package_name="ZOK_LOCAL",
session_id=session_id,
session_state=session_state
)
session_state = fm_create_result["session_state"]
# Step 6: Lock Function Module
fm_lock_result = lock_function_module(
function_module_name="ZFM_TEST_FUNCTION",
session_id=session_id,
session_state=session_state
)
fm_lock_handle = fm_lock_result["lock_handle"]
# CRITICAL: Save session_id and session_state from Lock response
# These MUST be used in Update and Unlock operations
fm_lock_session_id = fm_lock_result["session_id"]
fm_lock_session_state = fm_lock_result["session_state"]
try:
# Step 7: Update Function Module
fm_source = """FUNCTION zfm_test_function.
*"----------------------------------------------------------------------
*"*"Local Interface:
*" IMPORTING
*" VALUE(IV_INPUT) TYPE STRING
*" EXPORTING
*" VALUE(EV_OUTPUT) TYPE STRING
*"----------------------------------------------------------------------
ev_output = |Hello from { iv_input }|.
ENDFUNCTION."""
# CRITICAL: Use session_id and session_state from Lock response
fm_update_result = update_function_module(
function_module_name="ZFM_TEST_FUNCTION",
source_code=fm_source,
lock_handle=fm_lock_handle,
session_id=fm_lock_session_id, # ← From Lock response
session_state=fm_lock_session_state # ← From Lock response
)
session_state = fm_update_result["session_state"]
finally:
# Step 8: Unlock Function Module
# CRITICAL: Use session_id and session_state from Lock response
unlock_function_module(
function_module_name="ZFM_TEST_FUNCTION",
lock_handle=fm_lock_handle,
session_id=fm_lock_session_id, # ← From Lock response
session_state=fm_lock_session_state # ← From Lock response
)
session_state = unlock_result["session_state"]
finally:
# Step 9: Unlock Function Group
# CRITICAL: Use session_id and session_state from Lock response
unlock_result = unlock_function_group(
function_group_name="ZFG_MY_GROUP",
lock_handle=fg_lock_handle,
session_id=fg_lock_session_id, # ← From Lock response
session_state=fg_lock_session_state # ← From Lock response
)
session_state = unlock_result["session_state"]
# Step 10: Activate Function Group
activate_result = activate_function_group(
function_group_name="ZFG_MY_GROUP",
session_id=session_id,
session_state=session_state
)
print("✅ Function group and function module created and activated successfully!")
except Error as e:
print(f"❌ Error: {e}")
# Unlock both function module and function group if locked
if 'fm_lock_handle' in locals():
try:
unlock_function_module(
function_module_name="ZFM_TEST_FUNCTION",
lock_handle=fm_lock_handle,
session_id=session_id,
session_state=session_state
)
except:
pass
if 'fg_lock_handle' in locals():
try:
unlock_function_group(
function_group_name="ZFG_MY_GROUP",
lock_handle=fg_lock_handle,
session_id=session_id,
session_state=session_state
)
except:
pass
```
## Function Module Source Code Format
Function modules use standard ABAP function syntax:
```abap
FUNCTION zfm_test_function.
*"----------------------------------------------------------------------
*"*"Local Interface:
*" IMPORTING
*" VALUE(IV_INPUT) TYPE STRING
*" EXPORTING
*" VALUE(EV_OUTPUT) TYPE STRING
*" CHANGING
*" VALUE(CV_VALUE) TYPE STRING OPTIONAL
*" TABLES
*" IT_TABLE TYPE TABLE_TYPE OPTIONAL
*"----------------------------------------------------------------------
ev_output = |Hello from { iv_input }|.
ENDFUNCTION.
```
## Important Notes
1. **Function groups cannot be updated directly** - You add function modules to them
2. **Two-level locking** - Function group and function module have separate locks
3. **Activation** - Activating the function group activates all function modules within it
4. **Lock order** - Lock function group first, then create/lock/update/unlock function modules, then unlock function group
## Common Errors
### Error: "Function group already exists"
- **Solution**: Delete the existing function group or choose a different name
### Error: "Function module must belong to a function group"
- **Solution**: Ensure the function group is created and locked before creating function modules
### Error: "Invalid lock handle"
- **Solution**:
- **CRITICAL**: You MUST use the `session_id` and `session_state` from the Lock response in Update and Unlock operations
- Lock, Update, and Unlock MUST be in the same session
- Always save `session_id` and `session_state` from Lock response and pass them to Update and Unlock
- Use the correct lock handle for each operation (function group vs function module)
## Best Practices
1. **Lock function group first** - Lock the function group before creating function modules
2. **Unlock in reverse order** - Unlock function modules before unlocking the function group
3. **Handle errors carefully** - Unlock both function module and function group in error handlers
4. **Activate after unlock** - Activate the function group after all unlocks are complete
## Related Tools
- `GetSession` - Get session ID and state
- `ValidateFunctionGroupLow` - Validate function group name
- `CreateFunctionGroupLow` - Create function group
- `LockFunctionGroupLow` - Lock function group
- `CreateFunctionModuleLow` - Create function module
- `LockFunctionModuleLow` - Lock function module
- `UpdateFunctionModuleLow` - Update function module source
- `UnlockFunctionModuleLow` - Unlock function module
- `UnlockFunctionGroupLow` - Unlock function group
- `ActivateFunctionGroupLow` - Activate function group
## See Also
- [Creating Classes](./CREATING_CLASSES.md) - Similar workflow for classes
- [Session Management](./SESSION_MANAGEMENT.md) - Understanding sessions
- [Common Patterns](./COMMON_PATTERNS.md) - Reusable patterns
