The Simple Object Access Protocol (SOAP) is a network protocol that is primarily used to exchange structured data between different applications via the Internet. It is based on XML and allows the exchange of information between different platforms and systems, regardless of their programming language or operating system. SOAP is particularly popular in enterprise applications due to its strict standards and reliable message format, which guarantees a high level of security.

In the context of CMIS, SOAP is used as one of the supported API technologies to ensure compatibility between various content management systems (CMS) and document management systems (DMS). By using SOAP as an interface, companies can facilitate the exchange of data and the transfer of information between different systems without having to deal with the technical differences between the platforms. CMIS uses SOAP to provide standardized procedures for accessing, storing and managing documents, resulting in efficient integration of different systems.