Presentation of the Library

 

General Information

Library Overview

With the HttpHandling library, you can implement the HTTP client functionality in your controller application. The library supports the HTTP version 1.1.

 

 

The HTTP (Hypertext Transfer Protocol) function is a request-response protocol in the client/server computing model. For the connection between a client and a server, the TCP (Transport Layer Protocol) is used. The client submits an HTTP request message to the server. The server returns a response message to the client. The response contains status information about the request and may also contain requested content in its message text.

This library supports HTTP via a secured connection using TLS (Transport Layer Security), also known as HTTPS. Whether a connection using TLS is supported depends on the controller where the FB_HttpClient is used. Refer to the specific manual of your controller to verify if TCP communication using TLS is supported.

Characteristics of the Library

The following table indicates the characteristics of the library:

NOTE: For this library, qualified-access-only is set. This means, that the POUs, data structures, enumerations, and constants have to be accessed using the namespace of the library. The default namespace of the library is SE_HTTP.

Function Template

In EcoStruxure Machine Expert, the function template HttpClient is provided as part in the function template library Communication Functions. This function template supports you on implementing an HTTP client in your application.

For more information about this function template and the general use of function templates, refer to the Function Template Library Guide.

General Considerations

Only IPv4 IP addresses are supported for the communication functions provided with this library.

The library described in this document internally uses the TcpUdpCommunication library.

The TcpUdpCommunication (Schneider Electric) and the CAA Net Base Services library (CAA Technical Workgroup) use the same system resources on the controller. The simultaneous use of both libraries in the same application may lead to disturbances during the operation of the controller.