A web service ( WS ) is either:
54-434: WS-SecureConversation is a Web Services specification, created by IBM and others, that works in conjunction with WS-Security , WS-Trust and WS-Policy to allow the creation and sharing of security contexts. Extending the use cases of WS-Security , the purpose of WS-SecureConversation is to establish security contexts for multiple SOAP message exchanges, reducing the overhead of key establishment. WS-SecureConversation
108-549: A numeric character reference . Consider the Chinese character "中", whose numeric code in Unicode is hexadecimal 4E2D, or decimal 20,013. A user whose keyboard offers no method for entering this character could still insert it in an XML document encoded either as 中 or 中 . Similarly, the string "I <3 Jörg" could be encoded for inclusion in an XML document as I <3 Jörg . �
162-506: A network address over the Web with the service always-on as in the concept of utility computing. Many organizations use multiple software systems for management. Different software systems often need to exchange data with each other, and a Web service is a method of communication that allows two software systems to exchange this data over the Internet. The software system that requests data
216-503: A Web service to allow syndication . Another application offered to the end-user may be a mashup , where a Web server consumes several Web services at different machines and compiles the content into one user interface. Asynchronous JavaScript and XML (AJAX) is a dominant technology for Web services. Developing from the combination of HTTP servers, JavaScript clients and Plain Old XML (as distinct from SOAP and W3C Web Services), now it
270-449: A file called WSDL (Web Services Description Language), which has a .wsdl extension. (Proposals for Autonomous Web Services ( AWS ) seek to develop more flexible Web services that do not rely on strict rules. ) A directory called UDDI (Universal Description, Discovery, and Integration) defines which software system should be contacted for which type of data. So when one software system needs one particular report/data, it would go to
324-448: A list of syntax rules provided in the specification. Some key points in the fairly lengthy list include: The definition of an XML document excludes texts that contain violations of well-formedness rules; they are simply not XML. An XML processor that encounters such a violation is required to report such errors and to cease normal processing. This policy, occasionally referred to as " draconian error handling", stands in notable contrast to
378-522: A mechanism whereby an XML processor can reliably, without any prior knowledge, determine which encoding is being used. Encodings other than UTF-8 and UTF-16 are not necessarily recognized by every XML parser (and in some cases not even UTF-16, even though the standard mandates it to also be recognized). XML provides escape facilities for including characters that are problematic to include directly. For example: There are five predefined entities : All permitted Unicode characters may be represented with
432-478: A message format and SOAP/HTTP in enveloping and transporting. Functional and non-functional testing of Web services is done with the help of WSDL parsing. Regression testing is performed by identifying the changes made to upgrade software. Web service regression testing needs can be categorized in three different ways, namely, changes in WSDL, changes in the code, and selective re-testing of operations. We can capture
486-555: A more compact non-XML syntax; the two syntaxes are isomorphic and James Clark 's conversion tool— Trang —can convert between them without loss of information. RELAX NG has a simpler definition and validation framework than XML Schema, making it easier to use and implement. It also has the ability to use datatype framework plug-ins ; a RELAX NG schema author, for example, can require values in an XML document to conform to definitions in XML Schema Datatypes. Schematron
540-420: A network. It has an interface described in a machine-processable format (specifically WSDL ). Other systems interact with the web service in a manner prescribed by its description using SOAP-messages, typically conveyed using HTTP with an XML serialization in conjunction with other web-related standards. W3C Web Services may use SOAP over HTTP protocol, allowing less costly (more efficient) interactions over
594-433: A reduced test suite from the old test suite. Web services testing can also be automated using several test automation tools like SoapUI , Oracle Application Testing Suite (OATS), Unified Functional Testing, Selenium, etc. Work-related to the capture and visualization of changes made to a Web service. Visualization and computation of changes can be done in the form of intermediate artifacts (Subset WSDL). The insight on
SECTION 10
#1732802380067648-506: A rich datatyping system and allow for more detailed constraints on an XML document's logical structure. XSDs also use an XML-based format, which makes it possible to use ordinary XML tools to help process them. xs:schema element that defines a schema: RELAX NG (Regular Language for XML Next Generation) was initially specified by OASIS and is now a standard (Part 2: Regular-grammar-based validation of ISO/IEC 19757 – DSDL ). RELAX NG schemas may be written in either an XML based syntax or
702-421: A validity error must be able to report it, but may continue normal processing. A DTD is an example of a schema or grammar . Since the initial publication of XML 1.0, there has been substantial work in the area of schema languages for XML. Such schema languages typically constrain the set of elements that may be used in a document, which attributes may be applied to them, the order in which they may appear, and
756-527: A vocabulary to refer to the constructs within an XML document, but does not provide any guidance on how to access this information. A variety of APIs for accessing XML have been developed and used, and some have been standardized. Existing APIs for XML processing tend to fall into these categories: Stream-oriented facilities require less memory and, for certain tasks based on a linear traversal of an XML document, are faster and simpler than other alternatives. Tree-traversal and data-binding APIs typically require
810-484: A web service, a web technology such as HTTP is used for transferring machine-readable file formats such as XML and JSON. In practice, a web service commonly provides an object-oriented web-based interface to a database server, utilized for example by another web server, or by a mobile app , that provides a user interface to the end-user. Many organizations that provide data in formatted HTML pages will also provide that data on their server as XML or JSON, often through
864-461: Is a lexical , event-driven API in which a document is read serially and its contents are reported as callbacks to various methods on a handler object of the user's design. SAX is fast and efficient to implement, but difficult to use for extracting information at random from the XML, since it tends to burden the application author with keeping track of what part of the document is being processed. It
918-456: Is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable . The World Wide Web Consortium 's XML 1.0 Specification of 1998 and several other related specifications —all of them free open standards —define XML. The design goals of XML emphasize simplicity, generality, and usability across
972-471: Is a development in Web services where emphasis has been moving to simpler representational state transfer (REST) based communications. Restful APIs do not require XML-based Web service protocols ( SOAP and WSDL) to support their interfaces. In relation to W3C Web services, the W3C defined a Web service as: A web service is a software system designed to support interoperable machine-to-machine interaction over
1026-726: Is a language for making assertions about the presence or absence of patterns in an XML document. It typically uses XPath expressions. Schematron is now a standard (Part 3: Rule-based validation of ISO/IEC 19757 – DSDL ). DSDL (Document Schema Definition Languages) is a multi-part ISO/IEC standard (ISO/IEC 19757) that brings together a comprehensive set of small schema languages, each targeted at specific problems. DSDL includes RELAX NG full and compact syntax, Schematron assertion language, and languages for defining datatypes, character repertoire constraints, renaming and entity expansion, and namespace-based routing of document fragments to different validators. DSDL schema languages do not have
1080-578: Is an XML industry data standard. XML is used extensively to underpin various publishing formats. One of the applications of XML is in the transfer of Operational meteorology (OPMET) information based on IWXXM standards. The material in this section is based on the XML Specification . This is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use. XML documents consist entirely of characters from
1134-498: Is better suited to situations in which certain types of information are always handled the same way, no matter where they occur in the document. Pull parsing treats the document as a series of items read in sequence using the iterator design pattern . This allows for writing of recursive descent parsers in which the structure of the code performing the parsing mirrors the structure of the XML being parsed, and intermediate parsed results can be used and accessed as local variables within
SECTION 20
#17328023800671188-571: Is called a service requester , whereas the software system that would process the request and provide the data is called a service provider . Different software may use different programming languages, and hence there is a need for a method of data exchange that doesn't depend upon a particular programming language. Most types of software can, however, interpret XML tags. Thus, Web services can use XML files for data exchange. Rules for communication with different systems need to be defined, such as: All of these rules for communication are defined in
1242-467: Is frequently used with JSON as well as, or instead of, XML. Representational State Transfer (REST) is an architecture for well-behaved Web services that can function at Internet scale. In a 2004 document, the W3C sets following REST as a key distinguishing feature of Web services: We can identify two major classes of Web services: There are a number of Web services that use markup languages: A Web API
1296-452: Is meant to provide an extensible framework and a flexible syntax, with which one could implement various security mechanisms. It does not by itself guarantee security, but the implementor has to ensure that the result is not vulnerable to any attack. Following a pattern similar to TLS , WS-SecureConversation establishes a kind of session key. The processing overhead for key establishment is reduced significantly when compared to WS-Security in
1350-442: Is not permitted because the null character is one of the control characters excluded from XML, even when using a numeric character reference. An alternative encoding mechanism such as Base64 is needed to represent such characters. Comments may appear anywhere in a document outside other markup. Comments cannot appear before the XML declaration. Comments begin with <!-- and end with --> . For compatibility with SGML ,
1404-509: The Internet . It is a textual data format with strong support via Unicode for different human languages . Although the design of XML focuses on documents, the language is widely used for the representation of arbitrary data structures , such as those used in web services . Several schema systems exist to aid in the definition of XML-based languages, while programmers have developed many application programming interfaces (APIs) to aid
1458-458: The Unicode repertoire. Except for a small number of specifically excluded control characters , any character defined by Unicode may appear within the content of an XML document. XML includes facilities for identifying the encoding of the Unicode characters that make up the document, and for expressing characters that, for one reason or another, cannot be used directly. Unicode code points in
1512-471: The XML , SOAP, WSDL and UDDI open standards over an Internet Protocol backbone. XML is the data format used to contain the data and provide metadata around it, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI lists what services are available. A Web service is a method of communication between two electronic devices over a network. It is a software function provided at
1566-410: The infoset augmentation facility and attribute defaults. RELAX NG and Schematron intentionally do not provide these. A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0. It is frequently the case that the term "XML" is used to refer to XML together with one or more of these other technologies that have come to be seen as part of
1620-526: The Internet than via proprietary solutions like EDI/B2B. Besides SOAP over HTTP, Web services can also be implemented on other reliable transport mechanisms like FTP . In a 2002 document, the Web Services Architecture Working Group defined a Web services architecture, requiring a standardized implementation of a "Web service." The term "Web service" describes a standardized way of integrating Web-based applications using
1674-584: The SOAP protocol. Automated tools can aid in the creation of a Web service. For services using WSDL, it is possible to either automatically generate WSDL for existing classes (a bottom-up model) or to generate a class skeleton given existing WSDL (a top-down model). Critics of non-RESTful Web services often complain that they are too complex and based upon large software vendors or integrators, rather than typical open source implementations. There are also concerns about performance due to Web services' use of XML as
WS-SecureConversation - Misplaced Pages Continue
1728-462: The UDDI and find out which other systems it can contact for receiving that data. Once the software system finds out which other systems it should contact, it would then contact that system using a special protocol called SOAP (Simple Object Access Protocol). The service provider system would first validate the data request by referring to the WSDL file, and then process the request and send the data under
1782-429: The XML core. Some other specifications conceived as part of the "XML Core" have failed to find wide adoption, including XInclude , XLink , and XPointer . The design goals of XML include, "It shall be easy to write programs which process XML documents." Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The XML Infoset specification provides
1836-506: The XML processor inserts in the DTD itself and in the XML document wherever they are referenced, like character escapes. DTD technology is still used in many applications because of its ubiquity. A newer schema language, described by the W3C as the successor of DTDs, is XML Schema , often referred to by the initialism for XML Schema instances, XSD (XML Schema Definition). XSDs are far more powerful than DTDs in describing XML languages. They use
1890-528: The above three needs in three intermediate forms of Subset WSDL, namely, Difference WSDL (DWSDL), Unit WSDL (UWSDL), and Reduced WSDL (RWSDL), respectively. These three Subset WSDLs are then combined to form Combined WSDL (CWSDL) that is further used for regression testing of the Web service. This will help in Automated Web Service Change Management (AWSCM), by performing the selection of the relevant test cases to construct
1944-434: The allowable parent/child relationships. The oldest schema language for XML is the document type definition (DTD), inherited from SGML. DTDs have the following benefits: DTDs have the following limitations: Two peculiar features that distinguish DTDs from other schema types are the syntactic support for embedding a DTD within XML documents and for defining entities , which are arbitrary fragments of text or markup that
1998-621: The base language for communication protocols such as SOAP and XMPP . It is one of the message exchange formats used in the Asynchronous JavaScript and XML (AJAX) programming technique. Many industry data standards, such as Health Level 7 , OpenTravel Alliance , FpML , MISMO , and National Information Exchange Model are based on XML and the rich features of the XML schema specification. In publishing, Darwin Information Typing Architecture
2052-401: The behavior of programs that process HTML , which are designed to produce a reasonable result even in the presence of severe markup errors. XML's policy in this area has been criticized as a violation of Postel's law ("Be conservative in what you send; be liberal in what you accept"). The XML specification defines a valid XML document as a well-formed XML document which also conforms to
2106-423: The case of C1 characters, this restriction is a backwards incompatibility; it was introduced to allow common encoding errors to be detected. The code point U+0000 (Null) is the only character that is not permitted in any XML 1.1 document. The Unicode character set can be encoded into bytes for storage or transmission in a variety of different ways, called "encodings". Unicode itself defines encodings that cover
2160-461: The case of frequent message exchanges. However, a new layer is put on top of WS-Security, that implies other WS-* protocols like WS-Addressing and WS-Trust. So the importance of performance has to be compared to the added complexity and dependencies. See the performance section in WS-Security. The following specifications are associated with WS-SecureConversation: Web Services In
2214-581: The computation of change impact is helpful in testing, top-down development and reduce regression testing. AWSCM is a tool that can identify subset operations in a WSDL file to construct a subset WSDL. While UDDI was intended to serve as a service directory and become the means to discovering web services, many vendors discontinued their UDDI solutions or repositories between 2005-2008, including Microsoft, SAP, IBM, among others. A key study published in WWW2008 Conference (Beijing, China) presented
WS-SecureConversation - Misplaced Pages Continue
2268-429: The data structure and contain metadata . What is within the tags is data, encoded in the way the XML standard specifies. An additional XML schema (XSD) defines the necessary metadata for interpreting and validating XML. (This is also referred to as the canonical schema.) An XML document that adheres to basic XML rules is "well-formed"; one that adheres to its schema is "valid." IETF RFC 7303 (which supersedes
2322-442: The direct use of almost any Unicode character in element names, attributes, comments, character data, and processing instructions (other than the ones that have special symbolic meaning in XML itself, such as the less-than sign, "<"). The following is a well-formed XML document including Chinese , Armenian and Cyrillic characters: The XML specification defines an XML document as a well-formed text, meaning that it satisfies
2376-523: The entire repertoire; well-known ones include UTF-8 (which the XML standard recommends using, without a BOM ) and UTF-16 . There are many other text encodings that predate Unicode, such as ASCII and various ISO/IEC 8859 ; their character repertoires are in every case subsets of the Unicode character set. XML allows the use of any of the Unicode-defined encodings and any other encodings whose characters also appear in Unicode. XML also provides
2430-498: The following ranges are valid in XML 1.0 documents: XML 1.1 extends the set of allowed characters to include all the above, plus the remaining characters in the range U+0001–U+001F. At the same time, however, it restricts the use of C0 and C1 control characters other than U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return), and U+0085 (Next Line) by requiring them to be written in escaped form (for example U+0001 must be written as  or its equivalent). In
2484-708: The functions performing the parsing, or passed down (as function parameters) into lower-level functions, or returned (as function return values) to higher-level functions. Examples of pull parsers include Data::Edit::Xml in Perl , StAX in the Java programming language, XMLPullParser in Smalltalk , XMLReader in PHP , ElementTree.iterparse in Python , SmartXML in Red , System.Xml.XmlReader in
2538-550: The older RFC 3023 ), provides rules for the construction of media types for use in XML message. It defines three media types: application/xml ( text/xml is an alias), application/xml-external-parsed-entity ( text/xml-external-parsed-entity is an alias) and application/xml-dtd . They are used for transmitting raw XML files without exposing their internal semantics . RFC 7303 further recommends that XML-based languages be given media types ending in +xml , for example, image/svg+xml for SVG . Further guidelines for
2592-449: The processing of XML data. The main purpose of XML is serialization , i.e. storing, transmitting, and reconstructing arbitrary data. For two disparate systems to exchange information, they need to agree upon a file format. XML standardizes this process. It is therefore analogous to a lingua franca for representing information. As a markup language , XML labels, categorizes, and structurally organizes information. XML tags represent
2646-487: The rules of a Document Type Definition (DTD). In addition to being well formed, an XML document may be valid . This means that it contains a reference to a Document Type Definition (DTD), and that its elements and attributes are declared in that DTD and follow the grammatical rules for them that the DTD specifies. XML processors are classified as validating or non-validating depending on whether or not they check XML documents for validity. A processor that discovers
2700-406: The state of SOAP-based web services and concluded that only 63% of the available SOAP-based web services at the time of the study were actually active or can be invoked. The study also found that search engines were becoming an ideal source for searching for web services compared to that of service registries like the UDDI due its design complexity. XML Extensible Markup Language ( XML )
2754-469: The string "--" (double-hyphen) is not allowed inside comments; this means comments cannot be nested. The ampersand has no special significance within comments, so entity and character references are not recognized as such, and there is no way to represent characters outside the character set of the document encoding. An example of a valid comment: <!--no need to escape <code> & such in comments--> XML 1.0 (Fifth Edition) and XML 1.1 support
SECTION 50
#17328023800672808-474: The use of XML in a networked context appear in RFC 3470 , also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language. XML has come into common use for the interchange of data over the Internet. Hundreds of document formats using XML syntax have been developed, including RSS , Atom , Office Open XML , OpenDocument , SVG , COLLADA , and XHTML . XML also provides
2862-472: The use of much more memory, but are often found more convenient for use by programmers; some include declarative retrieval of document components via the use of XPath expressions. XSLT is designed for declarative description of XML document transformations, and has been widely implemented both in server-side packages and Web browsers. XQuery overlaps XSLT in its functionality, but is designed more for searching of large XML databases . Simple API for XML (SAX)
2916-426: The vendor support of XML Schemas yet, and are to some extent a grassroots reaction of industrial publishers to the lack of utility of XML Schemas for publishing . Some schema languages not only describe the structure of a particular XML format but also offer limited facilities to influence processing of individual XML files that conform to this format. DTDs and XSDs both have this ability; they can for instance provide
#66933