> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-software/configure/interface-options/api/controller-api-ftcapi-and-middleware-f/controller-api-server-and-middleware.md).

# Controller API - server and middleware

Understand Controller API and middleware installation, ports, and capacity limits.

This is the controller-level integration stack for third-party systems that talk **through a Gallagher controller** rather than through the REST API. Two components share one DLL.

> ⚠️ You cannot install both the Controller API and the FTCAPI on the same computer. They use the same DLL and cannot co-exist. For an HTTP, language-independent integration instead, use the [REST API](/knowledge-hub/products/cc-software/configure/interface-options/api/representational-state-transfer-rest-api/rest-api-features.md).

## FMF compared with FTCAPI

|               | FMF (FTCAPI Middleware Framework)                                | FTCAPI (FT Controller API)                     |
| ------------- | ---------------------------------------------------------------- | ---------------------------------------------- |
| For           | **Gallagher-developed** integrations                             | **Third-party-developed** integrations         |
| Nature        | Middleware layer via the **FTCAPI Router Service**               | Controller-level API; **no service installed** |
| Mechanisms    | ASCII text, SNMP                                                 | Direct DLL calls through the controller        |
| Installs from | `…\Utilities\System Interfaces\Middleware Framework vMFX.XX.XXX` | `…\Utilities\Controller API`                   |

Both install `GallagherFTCAPI.dll` and `GallagherFTCAPI.pem`. The controller is the communication bridge. The **`.pem` must be taken to a Command Centre workstation to generate a `GallagherFTCAPI.ini`**. That file holds the encryption key the DLL uses to talk to the controller, plus the comms **port (default 1073)**, so the controller listen port stays on **1072**.

## Limits

* **7.50+:** no explicit limit on External System Items (ESIs) per External System. The limit is the controller's resources.
* **7.40 and earlier:** a maximum of **100 ESIs per External System**.
* Tested figures: **2,500 ESIs on one C6000** (configuration took minutes to stabilise), and **250 External Systems with 4 ESIs each on a C6000**.

***

🔗 **Related**

* [Controller API - FTCAPI.ini File](/knowledge-hub/products/cc-software/configure/interface-options/api/controller-api-ftcapi-and-middleware-f/controller-api-ftcapi.ini-file.md). How to generate and place the ini file.
* [Controller API - FTCAPI Error Messages](/knowledge-hub/products/cc-software/configure/interface-options/api/controller-api-ftcapi-and-middleware-f/controller-api-ftcapi-error-messages.md). Diagnose registration and port errors.


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