SOAP, originally defined as Simple Object Access Protocol, is a protocol In computing and telecommunications, a protocol or communications protocol is a formal description of message formats and the rules for exchanging those messages. Protocols may include signaling, authentication and error detection and correction capabilities. In its simplest form, a protocol can be defined as the rules governing the syntax, specification for exchanging structured information in the implementation of Web Services Web services are typically application programming interfaces or web APIs that are accessed via Hypertext Transfer Protocol (HTTP) and executed on a remote system hosting the requested services. Web services tend to fall into one of two camps: Big Web Services and RESTful Web Services in computer networks A computer network, often simply referred to as a network, is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics. This article provides a general. It relies on eXtensible Markup Language XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards (XML) as its message format, and usually relies on other Application Layer Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite define application layers protocols (most notably Remote Procedure Call Remote procedure call is an Inter-process communication technology that allows a computer program to cause a subroutine or procedure to execute in another address space (commonly on another computer on a shared network) without the programmer explicitly coding the details for this remote interaction. That is, the programmer would write essentially (RPC) and HTTP The Hypertext Transfer Protocol is an Application Layer protocol for distributed, collaborative, hypermedia information systems) for message negotiation and transmission. SOAP can form the foundation layer of a web services protocol stack A web service protocol stack is a protocol stack that is used to define, locate, implement, and make Web services interact with each other. A web service protocol stack typically stacks four protocols:, providing a basic messaging framework upon which web services can be built. This XML based protocol consists of three parts: an envelope (which defines what is in the message and how to process it), a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing procedure calls and responses.

As a layman's example of how SOAP procedures can be used, a SOAP message could be sent to a web-service-enabled web site (for example, a real-estate price database) with the parameters needed for a search. The site would then return an XML-formatted document with the resulting data (prices, location, features, etc). Because the data is returned in a standardized machine-parseable format, it could then be integrated directly into a third-party web site or application.

The SOAP architecture consists of several layers of specifications: for message format, Message Exchange Patterns (MEP), underlying transport protocol bindings, message processing models, and protocol extensibility. SOAP is the successor of XML-RPC XML-RPC is a remote procedure call protocol which uses XML to encode its calls and HTTP as a transport mechanism, though it borrows its transport and interaction neutrality and the envelope/header/body from elsewhere (probably from WDDX WDDX is a programming-language-, platform- and transport-neutral data interchange mechanism to pass data between different environments and different computers. It supports simple data types such as number, string, boolean, etc., and complex aggregates of these in forms such as structures, arrays and recordsets (row/column data, typically coming).^{[speculation?]}

History

SOAP once stood for 'Simple Object Access Protocol' but this acronym was dropped with Version 1.2 of the standard.^[1] Version 1.2 became a W3C The World Wide Web Consortium is the main international standards organization for the World Wide Web (abbreviated WWW or W3) recommendation on June 24, 2003. The acronym is sometimes confused with SOA, which stands for Service-oriented architecture In computing, a service-oriented architecture is a flexible set of design principles used during the phases of systems development and integration. A deployed SOA-based architecture will provide a loosely-integrated suite of services that can be used within multiple business domains; however SOAP is different from SOA.

SOAP was originally designed by Dave Winer Dave Winer is an American software developer, entrepreneur and writer in Berkeley, California. A pioneer in the areas of outliners, content management, XML-RPC, RSS, OPML, and the MetaWeblog API, he is also noted for his contribution to podcasting. Winer is the author of Scripting News, one of the oldest weblogs, established in 1997. He is also, Don Box, Bob Atkinson, and Mohsen Al-Ghosein in 1998 in a project for Microsoft Microsoft Corporation is a public multinational corporation based in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions. Established on April 4, 1975 to develop and sell BASIC interpreters for the Altair 8800, (where Atkinson and Al-Ghosein were already working at the time)^[2], as an object-access protocol. The SOAP specification is currently maintained by the XML Protocol Working Group of the World Wide Web Consortium The World Wide Web Consortium is the main international standards organization for the World Wide Web (abbreviated WWW or W3).

After SOAP was first launched, it became the underlying layer of a more complex set of Web Services Web services are typically application programming interfaces or web APIs that are accessed via Hypertext Transfer Protocol (HTTP) and executed on a remote system hosting the requested services. Web services tend to fall into one of two camps: Big Web Services and RESTful Web Services, based on Web Services Description Language The current version of the specification is 2.0; version 1.1 has not been endorsed by the W3C but version 2.0 is a W3C recommendation. WSDL 1.2 was renamed WSDL 2.0 because of its substantial differences from WSDL 1.1. By accepting binding to all the HTTP request methods WSDL 2.0 specification offers better support for RESTful web services, and is (WSDL) and Universal Description Discovery and Integration (UDDI). These services, especially UDDI, have proved to be of far less interest, but an appreciation of them gives a fuller understanding of the expected role of SOAP compared to how web services have actually developed.

The SOAP specification

The SOAP specification defines the messaging framework which consists of:

• The SOAP processing model defining the rules for processing a SOAP message
• The SOAP extensibility model defining the concepts of SOAP features and SOAP modules
• The SOAP underlying protocol binding framework describing the rules for defining a binding to an underlying protocol that can be used for exchanging SOAP messages between SOAP nodes
• The SOAP message construct defining the structure of a SOAP message

SOAP processing model

The SOAP processing model describes a distributed processing model, its participants, the SOAP nodes and how a SOAP receiver processes a SOAP message. The following SOAP nodes are defined:

• SOAP sender

A SOAP node that transmits a SOAP message.

• SOAP receiver

A SOAP node that accepts a SOAP message.

• SOAP message path

The set of SOAP nodes through which a single SOAP message passes.

• Initial SOAP sender (Originator)

The SOAP sender that originates a SOAP message at the starting point of a SOAP message path.

• SOAP intermediary

A SOAP intermediary is both a SOAP receiver and a SOAP sender and is targetable from within a SOAP message. It processes the SOAP header blocks targeted at it and acts to forward a SOAP message towards an ultimate SOAP receiver.

• Ultimate SOAP receiver

The SOAP receiver that is a final destination of a SOAP message. It is responsible for processing the contents of the SOAP body and any SOAP header blocks targeted at it. In some circumstances, a SOAP message might not reach an ultimate SOAP receiver, for example because of a problem at a SOAP intermediary. An ultimate SOAP receiver cannot also be a SOAP intermediary for the same SOAP message.

Transport methods

SOAP makes use of an internet application layer Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite define application layers protocol as a transport protocol. Critics have argued that this is an abuse of such protocols, as it is not their intended function and therefore not a role they fulfill well. Proponents of SOAP have drawn analogies to successful uses of protocols at various levels for tunneling Computer networks use a tunneling protocol when one network protocol encapsulates a different payload protocol. By using tunneling one can (for example) carry a payload over an incompatible delivery-network, or provide a secure path through an untrusted network other protocols.^{[citation needed]}

Both SMTP Simple Mail Transfer Protocol is an Internet standard for electronic mail (e-mail) transmission across Internet Protocol (IP) networks. SMTP was first defined in RFC 821 (STD 15) (1982), and last updated by RFC 5321 (2008) which includes the extended SMTP (ESMTP) additions, and is the protocol in widespread use today. SMTP is specified for and HTTP The Hypertext Transfer Protocol is an Application Layer protocol for distributed, collaborative, hypermedia information systems are valid application layer protocols used as Transport for SOAP, but HTTP The Hypertext Transfer Protocol is an Application Layer protocol for distributed, collaborative, hypermedia information systems has gained wider acceptance as it works well with today's Internet infrastructure; specifically, HTTP works well with network firewalls A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device or set of devices which is configured to permit or deny computer applications based upon a set of rules and other criteria. SOAP may also be used over HTTPS Hypertext Transfer Protocol Secure is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure (website security testing) identification of the server. It uses port 443. HTTPS connections are often used for payment transactions on the World Wide Web and for sensitive transactions in corporate (which is the same protocol as HTTP at the application level, but uses an encrypted transport protocol underneath) with either simple or mutual authentication; this is the advocated WS-I method to provide web service security as stated in the WS-I Basic Profile 1.1.

This is a major advantage over other distributed protocols like GIOP/IIOP or DCOM Distributed Component Object Model is a proprietary Microsoft technology for communication among software components distributed across networked computers. DCOM, which originally was called "Network OLE", extends Microsoft's COM, and provides the communication substrate under Microsoft's COM+ application server infrastructure. It has which are normally filtered by firewalls. SOAP over AMQP is yet another possibility that some implementations support.

Message format

XML XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards was chosen as the standard message format because of its widespread use by major corporations and open source Open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology. Before the term open source became widely adopted, developers and producers used a variety of phrases to describe the concept; open source development efforts. Additionally, a wide variety of freely available tools significantly eases the transition to a SOAP-based implementation. The somewhat lengthy syntax In linguistics, syntax is the study of the principles and rules for constructing sentences in natural languages of XML XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards can be both a benefit and a drawback. While it promotes readability for humans, facilitates error detection, and avoids interoperability problems such as byte-order (Endianness In computing, endianness is the byte ordering used to represent some kind of data. Typical cases are the order in which integer values are stored as bytes in computer memory (relative to a given memory addressing scheme) and the transmission order over a network or other medium. When specifically talking about bytes, endianness is also referred to), it can retard processing speed and can be cumbersome. For example, CORBA The Common Object Request Broker Architecture is a standard defined by the Object Management Group (OMG) that enables software components written in multiple computer languages and running on multiple computers to work together, i.e. it supports multiple platforms, GIOP, ICE, and DCOM Distributed Component Object Model is a proprietary Microsoft technology for communication among software components distributed across networked computers. DCOM, which originally was called "Network OLE", extends Microsoft's COM, and provides the communication substrate under Microsoft's COM+ application server infrastructure. It has use much shorter, binary message formats. On the other hand, hardware appliances are available to accelerate processing of XML XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards messages.^[3][4] Binary XML is also being explored as a means for streamlining the throughput requirements of XML.

Sample SOAP message

POST /InStock HTTP/1.1
Host: www.example.org
Content-Type: application/soap+xml; charset=utf-8
Content-Length: nnn
<?xml version="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2001/12/soap-envelope"
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:Body xmlns:m="http://www.example.org/stock">
<m:GetStockPrice>
<m:StockName>IBM</m:StockName>
</m:GetStockPrice>
</soap:Body>
</soap:Envelope>

Technical critique

Advantages

• SOAP is versatile enough to allow for the use of different transport protocols. The standard stacks use HTTP as a transport protocol, but other protocols are also usable (e.g., JMS^[5], SMTP^[6]).
• Since the SOAP model tunnels fine in the HTTP get/response model, it can tunnel easily over existing firewalls and proxies, without modifications to the SOAP protocol, and can use the existing infrastructure.

Disadvantages

• Because of the verbose XML format, SOAP can be considerably slower than competing middleware Middleware is computer software that connects software components or some people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact. This technology evolved to provide for interoperability in support of the move to coherent distributed architectures, which technologies such as CORBA The Common Object Request Broker Architecture is a standard defined by the Object Management Group (OMG) that enables software components written in multiple computer languages and running on multiple computers to work together, i.e. it supports multiple platforms. This may not be an issue when only small messages are sent.^[7] To improve performance for the special case of XML with embedded binary objects, the Message Transmission Optimization Mechanism MTOM is the W3C Message Transmission Optimization Mechanism, a method of efficiently sending binary data to and from Web services was introduced.
• When relying on HTTP The Hypertext Transfer Protocol is an Application Layer protocol for distributed, collaborative, hypermedia information systems as a transport protocol and not using WS-Addressing or an ESB, the roles of the interacting parties are fixed. Only one party (the client) can use the services of the other. Developers must use polling Polling, or polled operation, in computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity. Polling is most often used in terms of input/output , and is also referred to as polled I/O or software driven I/O instead of notification in these common cases.
• Most uses of HTTP as a transport protocol are done in ignorance of how the operation would be modeled in HTTP.^{[8][dubious – discuss]} This is by design and similar to how different protocols sit on top of each other in the IP stack The Internet Protocol Suite is the set of communications protocols used for the Internet and other similar networks. It is commonly also known as TCP/IP, named from two of the most important protocols in it: the Transmission Control Protocol and the Internet Protocol (IP), which were the first two networking protocols defined in this standard. But this analogy is imperfect; the application protocols used as transport protocols aren't really transport protocols. As a result, there is no way to know if the method used is appropriate to the operation. This makes good analysis at the application-protocol level problematic with sub-optimal results—for example, a POST operation is used when it would more naturally be modeled as a GET. The REST Representational state transfer is a style of software architecture for distributed hypermedia systems such as the World Wide Web. The term Representational State Transfer (REST) was introduced and defined in 2000 by Roy Fielding in his doctoral dissertation. Fielding is one of the principal authors of the Hypertext Transfer Protocol (HTTP) architecture has become a web service Web services are typically application programming interfaces or web APIs that are accessed via Hypertext Transfer Protocol (HTTP) and executed on a remote system hosting the requested services. Web services tend to fall into one of two camps: Big Web Services and RESTful Web Services alternative that makes appropriate use of HTTP's defined methods.
• When relying on HTTP The Hypertext Transfer Protocol is an Application Layer protocol for distributed, collaborative, hypermedia information systems as a transport protocol, a firewall designed to only allow web browsing is forced to perform more detailed (and thus more costly) analysis of the HTTP packages. For example, an HTTP request to a SOAP WebService using the idempotent HTTP method GET, could easily be hiding non-idempotent actions inside the SOAP package, so firewalls must inspect the contents of the package and also have some knowledge of the SOAP structure, this may require parsing or string matching which is very costly in firewall terms. This is why it is generally a bad idea to use a transfer protocol such as HTTP as a transport protocol for which it was not designed.
• Although SOAP is an open standard, not all languages offer appropriate support. Java Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode (class file), Curl Curl is a reflective object-oriented programming language for interactive web applications whose goal is to provide a smoother transition from between formatting and programming; providing a means to embed more complex objects in simple documents without having to switch between programming languages or development platforms, Delphi Embarcadero Delphi, formerly CodeGear Delphi and Borland Delphi, is a software development environment for Microsoft Windows applications originally developed by Borland and now owned and developed by Embarcadero Technologies. Delphi 2010 is the most recent version and is distributed in three different editions: Professional, Enterprise and, PHP PHP: Hypertext Preprocessor is a widely used, general-purpose scripting language that was originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document. As a general-purpose, .NET The Microsoft .NET Framework is a software framework that can be installed on computers running Microsoft Windows operating systems. It includes a large library of coded solutions to common programming problems and a virtual machine that manages the execution of programs written specifically for the framework. The .NET Framework supports multiple and Flex Adobe Flex is a software development kit released by Adobe Systems for the development and deployment of cross-platform rich Internet applications based on the Adobe Flash platform. Flex applications can be written using Adobe Flex Builder or by using the freely available Flex compiler from Adobe offer SOAP integration and/or IDE support. Some Perl Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular amongst programmers. Larry Wall continues to oversee and Python Python is a general-purpose high-level programming language whose design philosophy emphasizes code readability. Python aims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive. Its use of indentation for block delimiters is unusual among popular programming languages support exists.

See also

• SOAP with Attachments
• SOAP with Attachments API for Java
• List of web service protocols
• Extensible User Interface Protocol (XUP) – a SOAP based UI protocol
• SOAPjr – a hybrid of SOAP and JR (JSON-RPC)
• Web Services Security

References

1. ^ SOAP Version 1.2 specification
2. ^ Exclusive .NET Developer's Journal "Indigo" Interview with Microsoft's Don Box
3. ^ IBM Datapower
4. ^ IBM Zurich XML Accelerator Engine
5. ^ http://www.w3.org/TR/2009/CR-soapjms-20090604/
6. ^ http://www.w3.org/TR/2001/WD-soap12-part0-20011217/#SMTP
7. ^ IBM Developer works
8. ^ Marchal, Benoit (2004). "SOAP 1.2 and the GET request". Developer Works. IBM. http://www.ibm.com/developerworks/xml/library/x-tipgetr.html. Retrieved 30 March 2010.

External links

• W3C SOAP page
• SOAP Version 1.2 specification
• SOAP Tutorial
• gSOAP - Open Source, Cross Platform, C/C++ SOAP Toolkit

Categories: World Wide Web Consortium standards | Application layer protocols | XML-based standards | Remote procedure call | Data serialization formats

See Also:

What Links Here:

Recently Viewed Pages:

• Home
• Metal: Blogs
• Pig Iron: Shopping
• Hot Rolling: Blogs
• Answers
• Crystal Lattice: Encyclopedia
• Renaissance: Encyclopedia
• Dislocation: Encyclopedia
• Automobile: Encyclopedia
• Steel Grade: Encyclopedia

Most Popular Pages:

• Cementite
• Ferrocement
• Sendzimir Process: Images
• ArcelorMittal: News
• Weathering Steel: Images
• Metal: Blogs
• El Mutún
• Coalbrookdale: Answers
• Ferrocement: News
• Hot Rolling: Blogs

Related 'Soap' Searches: