Difference Between SOAP and HTTP

SOAP was originally defined as S- Simple O- Object A-Access P-protocol. It is a protocol specification that is used for exchanging structured information. It is used in the implementation of web services in computer-based networks. For its message format, SOAP relies on XML Information set and sometimes relies on other application layer protocols as well, such as Hypertext Transfer Protocol (HTTP) or Simple Mail Transfer Protocol (SMTP). It is used for message negotiation and transmission mainly. SOAP forms the foundation layer of a web services protocol stack. The HTTP or Hypertext Transfer Protocol (HTTP) is an application protocol that is used for distributed, collaborative and hypermedia information systems. HTTP is widely regarded as the foundation of data communication for the World Wide Web (WWW). Hypertext is a structured text that uses logical links or hyperlinks between those nodes containing text. HTTP is the protocol for exchanging or transferring hypertext. When it was innovated, the standards development of HTTP was coordinated by the Internet Engineering Task Force and the World Wide Web Consortium, also called as W3C.

Head To Head Comparison Between SOAP and HTTP(Infographics)

Below is the top 9 difference between SOAP vs HTTP

Key Differences Between SOAP and HTTP

Both are popular choices in the market; let us discuss some of the major difference.

Users can serve any type of content over HTTP such as HTML, sound, images, video, etc. SOAP is an XML-based encoding of messages, as we already know that are typically sent over HTTP, but it could be sent over SMTP or even FTP type protocols as well, although the use of such a system in a production environment is rare.
HTTP sits on top of TCP/IP, and like that, SOAP sits on top of HTTP. We can imagine a Layer on top of layers.
If a SOAP request is looked at, we can see both layers; the HTTP headers layer will be at the top, followed by the SOAP message next to it.
SOAP usually deals with platform-independent data format (e.g. XML) to request and receive data from the application server.
HTTP handles network-level protocol.
An intuitive analogy to understand the difference would be like below:
SOAP as the person who packages the shipping box.
HTTP as the delivery truck that delivers the package.
HTTP protocol consists of two elements: an HTTP header and an HTTP body. When the HTTP body consists of pure XML document only and nothing else, then it is called Plain HTTP; however, in the SOAP format, the HTTP Body contains SOAP header and soap body is collectively known as SOAP envelope, and such envelope also supports attachments too.
HTTP URL: An example of an HTTP URL is as below.

http://host:port/abc/xi/adapter_plain?service=BS_A&namepsace=http_test&interface=SI_A>

SOAP URL: An example of SOAP URL is as below

http://host:port/XISOAPAdapter/MessageServlet?channel=party:service:channel

A SOAP message usually will be bundled within the soap envelope. HTTP does not act as an adapter in the adapter engine, but soap is actually an adapter, i.e. HTTP doesn’t require a communication channel for its communication, but SOAP requires that. Users can send soap messages using the SOAP client.
When a user needs to send his/her Data to XI from a Webservice, the user’s SOAP adapter is used.

The HTTP adapter is used when a user wants to post an HTTP request message from a web application to XI, so there is an important difference.

Example: <i>How can I make use of SOAP Sender Adapter without using any tools like XML Spy etc….</i>

XML Spy is used as a TEST tool most often when users send SOAP information to XI. However, to actually send data, the user needs to configure a web service first and then construct a SOAP request message and, after that, post the data.
The SOAP sender adapter is extraction for the XML message from the whole SOAP envelope message itself. Users can achieve the same using an HTTP adapter as well and a suitable mapping thereof. The HTTP adapter is better performing and stable than SOAP because only the ABAP part of WAS is used in this, also called the native adapter.

SOAP vs HTTP Comparison Table

Below is the 9 topmost comparison

SOAP	HTTP
It supports web socket or WS-Addressing, WS-Security and SOAP headers.	HTTP Message flows never use web socket or WS-Addressing, WS-Security, SwA, or MTOM.
A common SOAP has a logical tree format which is independent of the bitstream format.	HTTP is something that uses different standards, such as REST or XML-RPC.
Runtime checking against WSDL is permitted in SOAP.	Not available in HTTP.
Automatic processing of SOAP with Attachments (SwA) is possible here.	In HTTP, message flows that interact with Web services only.
Automatic processing of Message Transmission Optimization Mechanism (MTOM) is also feasible.	HTTP nodes can process SwA messages also, but they must use the MIME message domain, and design flow should be done to handle the attachments explicitly. Custom logic to extract and parse the SOAP should be written.
SOAP is a protocol to exchange XML-based messages, and SOAP should use HTTP to transport those messages, as already explained in the introduction section.	On the other hand, HTTP is a communications protocol that transports messages over a network, not like SOAP.
SOAP stands for Simple Object Access Protocol, as mentioned. It is a protocol that is used for accessing web services and based on XML structure.	Http or Hypertext Transfer Protocol is a transfer used protocol. It is also called a stateless protocol because each command is executed independently in HTTP. Commands need not have any knowledge of the commands that came before them.
SOAP provides a mechanism to communicate between applications that are running on different operating systems, with different technologies and, most time, programming languages too.	It is difficult to implement Web sites using HTTP that reacts intelligently to user inputs.
SOAP is just a data exchange protocol in use, the soap message inside the HTTP body in the protocol.	The above shortcoming of HTTP is being addressed in many new technologies such as ActiveX, Java, JavaScript etc.

Conclusion

SOAP messages are most often formatted in XML and are usually sent using HTTP. SOAP uses the WSDL method of communication between provider and consumer; on the other hand, REST just uses XML or JSON to send and receive data in most cases. SOAP builds an XML based protocol first, and then it uses HTTP on top of it or sometimes TCP/IP too. Thus, through this SOAP vs HTTP article, important differences in SOAP vs HTTP are explained and elaborated.

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