Simple Object Access Protocol
Soap. For other uses of the acronym SOAP, see Soap (disambiguation).
SOAP (formerly an acronym of Simple Object Access Protocol) is a light-weight protocol for exchanging messages between computer software, typically in the form of software componentry. The word object implies that the use should adhere to the object-oriented programming paradigm.
SOAP is an extensible and decentralized framework that can work over multiple computer network protocol stacks. Remote procedure calls can be modeled as an interaction of several SOAP messages. SOAP is one of the enabling protocols for Web services.
SOAP can be run on top of all the Internet Protocols, but HTTP is the most common and the only one standardized by the W3C. SOAP is based on XML, and its design follows the Head-Body software pattern, not unlike HTML. The optional Header contains meta-information such as information for routing, security, and transactions. The Body transports the main information, sometimes known as the payload. The payload is compliant with an XML Schema.
Example SOAP messages
By way of example, here is how a client might format a SOAP message requesting product information from a fictional warehouse web service:
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<getProductDetails xmlns="http://warehouse.example.com/ws">
<productId>827635</productId>
</getProductDetails>
</soap:Body>
</soap:Envelope>
Here is how the warehouse web service might format its reply message with the requested product information:
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<getProductDetailsResponse xmlns="http://warehouse.example.com/ws">
<getProductDetailsResult>
<productName>Toptimate 3-Piece Set</productName>
<productId>827635</productId>
<description>3-Piece luggage set. Black Polyester.</description>
<price>96.50</price>
<inStock>true</inStock>
</getProductDetailsResult>
</getProductDetailsResponse>
</soap:Body>
</soap:Envelope>
See also
