 | This article needs additional citations for verification .(October 2016) |
XML-RPC is a remote procedure call (RPC) protocol which uses XML to encode its calls and HTTP as a transport mechanism. [1]
| | This article needs additional citations for verification .(October 2016) |
XML-RPC is a remote procedure call (RPC) protocol which uses XML to encode its calls and HTTP as a transport mechanism. [1]
The XML-RPC protocol was created in 1998 by Dave Winer of UserLand Software and Microsoft, [2] with Microsoft seeing the protocol as an essential part of scaling up its efforts in business-to-business e-commerce. [3] As new functionality was introduced, the standard evolved into what is now SOAP. [4]
UserLand supported XML-RPC from version 5.1 of its Frontier web content management system, [4] released in June 1998. [5]
XML-RPC's idea of a human-readable-and-writable, script-parsable standard for HTTP-based requests and responses has also been implemented in competing specifications such as Allaire's Web Distributed Data Exchange (WDDX) and webMethod's Web Interface Definition Language (WIDL). [6] Prior art wrapping COM, CORBA, and Java RMI objects in XML syntax and transporting them via HTTP also existed in DataChannel's WebBroker technology. [7] [8]
The generic use of XML for remote procedure call (RPC) was patented by Phillip Merrick, Stewart Allen, and Joseph Lapp in April 2006, claiming benefit to a provisional application filed in March 1998. The patent was assigned to webMethods, located in Fairfax, Virginia. The patent expired on March 23, 2019. [9]
In XML-RPC, a client performs an RPC by sending an HTTP request to a server that implements XML-RPC and receives the HTTP response. A call can have multiple parameters and one result. The protocol defines a few data types for the parameters and result. Some of these data types are complex, i.e. nested. For example, you can have a parameter that is an array of five integers.
The parameters/result structure and the set of data types are meant to mirror those used in common programming languages.
Identification of clients for authorization purposes can be achieved using popular HTTP security methods. Basic access authentication can be used for identification and authentication.
In comparison to RESTful protocols, where resource representations (documents) are transferred, XML-RPC is designed to call methods. The practical difference is just that XML-RPC is much more structured, which means common library code can be used to implement clients and servers and there is less design and documentation work for a specific application protocol. One salient technical difference between typical RESTful protocols and XML-RPC is that many RESTful protocols use the HTTP URI for parameter information, whereas with XML-RPC, the URI just identifies the server.
JSON-RPC is similar to XML-RPC.
Common datatypes are converted into their XML equivalents with example values shown below:
| Name | Tag Example | Description |
|---|---|---|
| array | <array><data><value><i4>1404</i4></value><value><string>Somethinghere</string></value><value><i4>1</i4></value></data></array> | Array of values, storing no keys |
| base64 | <base64>eW91IGNhbid0IHJlYWQgdGhpcyE=</base64> | Base64-encoded binary data |
| boolean | <boolean>1</boolean> | Boolean logical value (0 or 1) |
| date/time | <dateTime.iso8601>19980717T14:08:55Z</dateTime.iso8601> | Date and time in ISO 8601 format |
| double | <double>-12.53</double> | Double precision floating point number |
| integer | <int>42</int>or <i4>42</i4> | Whole number, integer |
| string | <string>Helloworld!</string>or Helloworld! | String of characters. Must follow XML encoding. |
| struct | <struct><member><name>foo</name><value><i4>1</i4></value></member><member><name>bar</name><value><i4>2</i4></value></member></struct> | Associative array |
| nil | <nil/> | Discriminated null value; an XML-RPC extension |
An example of a typical XML-RPC request would be:
<?xml version="1.0"?><methodCall><methodName>examples.getStateName</methodName><params><param><value><i4>40</i4></value></param></params></methodCall>An example of a typical XML-RPC response would be:
<?xml version="1.0"?><methodResponse><params><param><value><string>SouthDakota</string></value></param></params></methodResponse>A typical XML-RPC fault would be:
<?xml version="1.0"?><methodResponse><fault><value><struct><member><name>faultCode</name><value><int>4</int></value></member><member><name>faultString</name><value><string>Toomanyparameters.</string></value></member></struct></value></fault></methodResponse>Recent critics (from 2010 and onwards) of XML-RPC argue that RPC calls can be made with plain XML, and that XML-RPC does not add any value over XML. Both XML-RPC and XML require an application-level data model, such as which field names are defined in the XML schema or the parameter names in XML-RPC. Furthermore, XML-RPC uses about 4 times the number of bytes compared to plain XML to encode the same objects, which is itself verbose compared to JSON. [10] [11] [12]
In distributed computing, a Remote Procedure Call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space, which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction. That is, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. This is a form of client–server interaction, typically implemented via a request–response message passing system. In the object-oriented programming paradigm, RPCs are represented by remote method invocation (RMI). The RPC model implies a level of location transparency, namely that calling procedures are largely the same whether they are local or remote, but usually, they are not identical, so local calls can be distinguished from remote calls. Remote calls are usually orders of magnitude slower and less reliable than local calls, so distinguishing them is important.
SOAP is a messaging protocol specification for exchanging structured information in the implementation of web services in computer networks. It uses XML Information Set for its message format, and relies on application layer protocols, most often Hypertext Transfer Protocol (HTTP), although some legacy systems communicate over Simple Mail Transfer Protocol (SMTP), for message negotiation and transmission.
In computing, the Java Remote Method Invocation is a Java API that performs remote method invocation, the object-oriented equivalent of remote procedure calls (RPC), with support for direct transfer of serialized Java classes and distributed garbage-collection.
The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between systems on different operating systems, programming languages, and computing hardware. CORBA uses an object-oriented model although the systems that use the CORBA do not have to be object-oriented. CORBA is an example of the distributed object paradigm.
A Jakarta Servlet, formerly Java Servlet is a Java software component that extends the capabilities of a server. Although servlets can respond to many types of requests, they most commonly implement web containers for hosting web applications on web servers and thus qualify as a server-side servlet web API. Such web servlets are the Java counterpart to other dynamic web content technologies such as PHP and ASP.NET.
A web service (WS) is either:
An interface description language or interface definition language (IDL) is a generic term for a language that lets a program or object written in one language communicate with another program written in an unknown language. IDLs are usually used to describe data types and interfaces in a language-independent way, for example, between those written in C++ and those written in Java.
WDDX is a programming language-, platform- and transport-neutral data interchange mechanism designed to pass data between different environments and different computers.
JSON is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays. It is a commonly used data format with diverse uses in electronic data interchange, including that of web applications with servers.
JSON-RPC is a remote procedure call (RPC) protocol encoded in JSON. It is similar to the XML-RPC protocol, defining only a few data types and commands. JSON-RPC allows for notifications and for multiple calls to be sent to the server which may be answered asynchronously.
XML Interface for Network Services (XINS) is an open-source technology for definition and implementation of internet applications, which enforces a specification-oriented approach.
A web API is an application programming interface (API) for either a web server or a web browser. As a web development concept, it can be related to a web application's client side. A server-side web API consists of one or more publicly exposed endpoints to a defined request–response message system, typically expressed in JSON or XML by means of an HTTP-based web server. A server API (SAPI) is not considered a server-side web API, unless it is publicly accessible by a remote web application.
The Spring Framework is an application framework and inversion of control container for the Java platform. The framework's core features can be used by any Java application, but there are extensions for building web applications on top of the Java EE platform. The framework does not impose any specific programming model.. The framework has become popular in the Java community as an addition to the Enterprise JavaBeans (EJB) model. The Spring Framework is free and open source software.
The Web Application Description Language (WADL) is a machine-readable XML description of HTTP-based web services. WADL models the resources provided by a service and the relationships between them. WADL is intended to simplify the reuse of web services that are based on the existing HTTP architecture of the Web. It is platform and language independent and aims to promote reuse of applications beyond the basic use in a web browser. WADL was submitted to the World Wide Web Consortium by Sun Microsystems on 31 August 2009, but the consortium has no current plans to standardize it. WADL is the REST equivalent of SOAP's Web Services Description Language (WSDL), which can also be used to describe REST web services.
In a distributed computing environment, distributed object communication realizes communication between distributed objects. The main role is to allow objects to access data and invoke methods on remote objects. Invoking a method on a remote object is known as remote method invocation (RMI) or remote invocation, and is the object-oriented programming analog of a remote procedure call (RPC).
In computer science, marshalling or marshaling is the process of transforming the memory representation of an object into a data format suitable for storage or transmission, especially between different runtimes. It is typically used when data must be moved between different parts of a computer program or from one program to another.
Jakarta RESTful Web Services, is a Jakarta EE API specification that provides support in creating web services according to the Representational State Transfer (REST) architectural pattern. JAX-RS uses annotations, introduced in Java SE 5, to simplify the development and deployment of web service clients and endpoints.
JSON-WSP is a web service protocol that uses JSON for service description, requests and responses. It is inspired from JSON-RPC, but the lack of a service description specification with documentation in JSON-RPC sparked the design of JSON-WSP.
The RESTful Service Description Language (RSDL) is a machine- and human-readable XML description of HTTP-based web applications.
Cap’n Proto is a data serialization format and Remote Procedure Call (RPC) framework for exchanging data between computer programs. The high-level design focuses on speed and security, making it suitable for network as well as inter-process communication. Cap'n Proto was created by the former maintainer of Google's popular Protocol Buffers framework and was designed to avoid some of its perceived shortcomings.