DOCSLIB.ORG

Implementation of XML-RPC

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Implementation of XML-RPC Programmieraufgabe CN 03/04 Pascal Zumkehr, Matthias Stürmer Remote Procedure Call (RPC) What is RPC RPC is a powerful technique for constructing distributed, client-server based applications. It is based on extending the notion of conventional, or local procedure calling, so that the called procedure need not exist in the same address space as the calling procedure. The two processes may be on the same system, or they may be on different systems with a network connecting them. By using RPC, programmers of distributed applications avoid the details of the interface with the network. The transport independence of RPC isolates the application from the physical and logical elements of the data communications mechanism and allows the application to use a variety of transports. How RPC Works An RPC is analogous to a function call. Like a function call, when an RPC is made, the calling arguments are passed to the remote procedure and the caller waits for a response to be returned from the remote procedure. The following image shows the flow of activity that takes place during an RPC call between two networked systems. The client makes a procedure call that sends a request to the server and waits. The thread is blocked from processing until either a reply is received, or it times out. When the request arrives, the server calls a dispatch routine that performs the requested service, and sends the reply to the client. After the RPC call is completed, the client program continues. A remote procedure is uniquely identified by the triple: (program number, version number, procedure number) The program number identifies a group of related remote procedures, each of which has a unique procedure number. A program may consist of one or more versions. Each version consists of a collection of procedures which are available to be called remotely. Version numbers enable multiple versions of an RPC protocol to be available simultaneously. Each version contains a a number of procedures that can be called remotely. Each procedure has a procedure number. Remote Procedure Calls are high-level communications mechanisms. RPC presumes the existence of low-level networking mechanisms (such as TCP/IP and UDP/IP), and implements on them a logical client-to-server communications system designed specifically for the support of network applications. With RPC, the client makes a procedure call to send a data packet to the server. When the packet arrives, the server calls a dispatch routine, performs whatever service is requested, sends back the reply, and returns the procedure call to the client. 7. Februar 2004 Seite 1 von 4 Programmieraufgabe CN 03/04 Pascal Zumkehr, Matthias Stürmer Layers of RPC The RPC interface can be seen as being divided into three layers. The Highest Layer The highest layer is totally transparent to the operating system, machine, and network on which it is run. Think of this level as a way of using RPC, rather than as a part of RPC itself. The Middle Layer The middle layer is really the heart of RPC. Here, the user does not need to consider details about sockets, the UNIX system, or other low-level implementation mechanisms. They simply make remote procedure calls to routines on other machines. The inherent value of this layer is its simplicity. It is this layer that allows RPC to pass the "hello world" test. The middle layer is rarely used in serious programming due to its simplicity. It does not allow timeout specifications or the choice of transport. It allows no UNIX process control or flexibility in case of errors. It does not support multiple types of call authentication. You rarely need all these types of control, but one or two of them is often necessary. The Lowest Layer The lowest layer lets you control these details, and for that reason it is often necessary. Programs written at this level are also most efficient, but this is usually not an issue, since RPC clients and servers rarely generate heavy network loads. The RPC Paradigm Here is a diagram of the RPC paradigm: 1. RPC client program issues an RPC call to a remote procedure. 2. RPC forwarder recognizes call to a mainframe service and forwards RPC call over the channel. 3. Mainframe RPC server accepts the call and forwards the request to the RPC application. Implementation and Syntax of XML-RPC As described before, the only things needed to send or process a remote procedure call are an HTTP processor and the XML file with the corresponding structures. In this section, the syntax of the HTTP Header and the XML file are going to be presented. An XML-RPC message is an HTTP-POST request with a common HTTP Header and an XML body. The reply given after processing by the server is also in XML format. 7. Februar 2004 Seite 2 von 4 Programmieraufgabe CN 03/04 Pascal Zumkehr, Matthias Stürmer HTTP Header Request POST /RPC2 HTTP/1.0 User-Agent: Frontier/5.1.2 (WinNT) Host: betty.userland.com Content-Type: text/xml Content-length: 181 The first line of the HTTP header tells the server that the type of the request is HTTP POST and also specifies the URI for the server. It can be empty or just a single slash for a server that just handles RPC requests, but usually, if other HTTP requests are processed, the URI helps the server to route the XML-RPC request to the handling code. In this example the server is told to route the request to the RPC2 responder, as it is done for the Google XML-RPC handler provided by xmlrpc.com. A User-Agent and a Host have to be specified to guarantee a correct handling of the request. The same is true for the Content-length (without the header), which also has to be correct. XML Body Request <?xml version="1.0"?> <methodCall> <methodName>googleGateway.spellingSuggestion</methodName> <params> <param> <value><string>Helo World</string></value> </param> <param> <value><int>1234567890</int></value> </param> </params> </methodCall> The structure of the XML is quite simple. There is only one main structure, called <methodCall>, and can contain two different sub-items: The <methodName> tag, which is mandatory, holding a string that specifies the name of the method to be called. It is entirely up to the server how this string is interpreted. So the methodName could be a file containing a script to execute or, like in this example, a path to find the method. The other sub-item is the <params> tag, which can contain any number of <param> tags, one for each parameter the method requests. If the method doesn’t take any parameters at all, the <params> tag doesn’t need to be specified. Each <param> tag contains a <value>, where the data type and the actual value are indicated. Allowed data types are <int>, <string>, <double>, <boolean>, <dateTime.iso8601>, <base64>, the default type is <string>. Furthermore, it is also possible to pass structures and arrays, which are both recursive, i.e. A <struct> can contain another <struct> in a <value>. The syntax for a structure is <struct>[<member><name>name</name> <value><type>value</type></value></member>]</struct>, for an array it’s <array><data> [<value><type>value</type></value>]</data></array>, it is allowed to mix the types in an array. Reply The response by the server looks quite similar. The first line of the HTTP Header contains always “HTTP/1.1 200 OK”, unless there is a lower-level error. The content type must be set to text/xml again, and also the content-length must be specified and correct. The important part is the XML body of the reply: The main structure is a <methodResponse> that can contain a single <params> that contains a single <param>, which contains a single <value>. In the case of an error, <methodResponse> can also contain a <fault> tag, which contains a 7. Februar 2004 Seite 3 von 4 Programmieraufgabe CN 03/04 Pascal Zumkehr, Matthias Stürmer <value> which is a <struct> having two <member>s, one named faultCode, an <int> and one named faultString, a <string> containing more information on the error. A <methodResponse> cannot contain both a <fault> and a <params> tag. <?xml version="1.0"?> <methodResponse> <params> <param> <value><string>Hello World</string></value> </param> </params> </methodResponse> Sources http://www.cisco.com/univercd/cc/td/doc/product/software/ioss390/ios390rp/rprdesc.htm http://www.xmlrpc.com http://ws.apache.org/xmlrpc/ Test Questions 1. What are the main advantages of RPC? 2. What are the six main steps of a RPC Call and who is doing them? 3. How many layers has the RPC interface and what are they called? 4. Name three different valid data type tags for XML-RPC 5. Do the elements of an array in XML-RPC have to be from the same data type? Answers 1. By using RPC, programmers of distributed applications avoid the details of the interface with the network. The transport independence of RPC isolates the application from the physical and logical elements of the data communications mechanism and allows the application to use a variety of transports. 2. Client: 1. callrpc function Server: 2. execute request 3. call service 4. executes service 5. request completes, return reply Client: 6. program continues 3. Three: The Highest Layer, the Middle Layer and the Lowest Layer 4. <int>, <string>, <boolean>, <double>, <base64>, <dateTime.iso8601> 5. No, as the data type is indicated separately in each <value> tag. 7. Februar 2004 Seite 4 von 4 .
Load more

Recommended publications
  • Remote Procedure Calls
    Lectures on distributed systems Remote Procedure Calls Paul Krzyzanowski Introduction, or what’s wrong with sockets? OCKETS are a fundamental part of client-server networking. They provide a S relatively easy mechanism for a program to establish a connection to another program, either on a remote or local machine and send messages back and forth (we can even use read and write system calls). This interface, however, forces us to design our distributed applications using a read/write (input/output) inter- face which is not how we generally design non-distributed applications. In design- ing centralized applications, the procedure call is usually the standard interface model. If we want to make distributed computing look like centralized comput- ing, input-output-based communications is not the way to accomplish this. In 1984, Birrell and Nelson devised a mechanism to allow programs to call procedures on other machines. A process on machine A can call a procedure on machine B. The process on A is suspended and execution continues on B. When B returns, the return value is passed to A and A continues execution. This mechanism is called the Remote Procedure Call (RPC). To the programmer, the goal is that it should appear as if a normal procedure call is taking place. Obvi- ously, a remote procedure call is different from a local one in the underlying implementation. Steps in a remote procedure call Clearly, there is no architectural support for making remote procedure calls. A local procedure call generally involves placing the calling parameters on the stack and executing some form of a call instruction to the address of the proce- dure.
    [Show full text]
  • Distributed Objects in C
    Rochester Institute of Technology RIT Scholar Works Theses 2006 Distributed Objects in C# Xiaoyun Xie Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Xie, Xiaoyun, "Distributed Objects in C#" (2006). Thesis. Rochester Institute of Technology. Accessed from This Master's Project is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Rochester Institute of Technology Department of Computer Science Master of Science Project Distributed Objects System in C# Submitted By: Xie, Xiaoyun (Sherry) Date: February 2004 Chairman: Dr. Axel T. Schreiner Reader: Dr. Hans-Peter Bischof Observer: Dr. James Heliotis 2 ABSTRACT Today more and more programs run over a collection of autonomous computers linked by a network and are designed to produce an integrated computing facility. Java Distributed Objects (JDO) proposed by Dr. Axel T. Schreiner [1] builds an infrastructure which allows distributed program components to communicate over a network in a transparent, reliable, efficient, and generic way. JDO was originally intended as a teaching device to assess design parameters for distributed objects. This project focuses on porting JDO, which is implemented in Java on Sun’s JDK, to C# on Microsoft’s .NET. On one hand, it builds an infrastructure in C# that simplifies the construction of distributed programs by hiding the distributed nature of remote objects. On the other hand, it generates insights into the differences between two platforms, namely, Java on Sun and C# on .NET, in the distributed objects area.
    [Show full text]
  • More Efficient Serialization and RMI for Java
    To appear in: Concurrency: Practice & Experience, Vol. 11, 1999. More Ecient Serialization and RMI for Java Michael Philippsen, Bernhard Haumacher, and Christian Nester Computer Science Department, University of Karlsruhe Am Fasanengarten 5, 76128 Karlsruhe, Germany [phlippjhaumajnester]@ira.u ka.de http://wwwipd.ira.uka.de/JavaPa rty/ Abstract. In current Java implementations, Remote Metho d Invo ca- tion RMI is to o slow, esp ecially for high p erformance computing. RMI is designed for wide-area and high-latency networks, it is based on a slow ob ject serialization, and it do es not supp ort high-p erformance commu- nication networks. The pap er demonstrates that a much faster drop-in RMI and an ecient drop-in serialization can b e designed and implemented completely in Java without any native co de. Moreover, the re-designed RMI supp orts non- TCP/IP communication networks, even with heterogeneous transp ort proto cols. We demonstrate that for high p erformance computing some of the ocial serialization's generality can and should b e traded for sp eed. Asaby-pro duct, a b enchmark collection for RMI is presented. On PCs connected through Ethernet, the b etter serialization and the improved RMI save a median of 45 maximum of 71 of the runtime for some set of arguments. On our Myrinet-based ParaStation network a cluster of DEC Alphas wesave a median of 85 maximum of 96, compared to standard RMI, standard serialization, and Fast Ethernet; a remote metho d invo cation runs as fast as 80 s round trip time, compared to ab out 1.5 ms.
    [Show full text]
  • Remote Procedure Call (RPC)
    Remote Procedure Call (RPC) RPC – RMI - Web Services 1 Complexity of the distributed applications . The programming of distributed applications is difficult. In addition to the usual tasks, programmers who build clients and servers must deal with the complex issues of communication. Although many of the needed functions are supplied by a standard API such as the socket interface, the socket calls require the programmer to specify many low level details as names ,addresses,protocols and ports. Moreover, asinchronous communications models are complex to implement. Distributed implementations tend to use the same standard API (e.g.,the socket interface). As a consequence most of the detailed code found in one program is replicated in others RPC – RMI - Web Services 2 . For example, all client programs that use a connection oriented transport must create a socket, specify the server’s endpoint address, open a connection to the server, send requests,receive responses and close the connection when interaction is complete. Tools (software that generates all or part of a computer program) have been created to construct clients and servers. Tools cannot eliminate all programming: a programmer must supply the code that perform the computation for the particular service. However, a tool can handle the communication details. As a result the code contains fever bugs. RPC – RMI - Web Services 3 . RPC = Remote Procedure Call . The basic model has been proposed by Birrell e Nelson in 1984. The essence of this technique is to allow programs on different machines to interact using simple procedure call/return semantics, just as if the two programs were in the same computer .
    [Show full text]
  • Inter Process Communication with Message Passing
    Operating systems (vimia219) Collaboration of Tasks Tamás Kovácsházy, PhD 13rd Topic Inter Process Communication with Message Passing Budapest University of Technology and Economics Department of Measurement and Information Systems Looking back, communication solutions . Using shared memory(RAM or PRAM model): o Among threads running in the context of a process (shared memory of the process) . Messages: o No shared memory • Among processes running inside an operating system • Distributed system (network communication) o Microkernel based operating system . Inter Process Communication, IPC © BME-MIT 2014, All Rights Reserved 2. lap Messages . Different from the same word used in computer networks o We consider a more generic notion of message . Message passing . For example: o System call o TCP/IP connection (TCP) or message (UDP) for internal (localhost) or external communication (among machines) . Most cases they are implemented as OS API function/method calls resulting a system call . The operating system implements them by its services © BME-MIT 2014, All Rights Reserved 3. lap Some notes . Semaphore, Critical section object, and Mutex are also implemented by the OS and handled by system calls o Threads running in the context of a process communicate using shared memory (fast, low resource utilization) o Mutual exclusion and synchronization are solved by messages (using system calls). o It has some overhead: • Experiments: Lockless programming, transactional memory etc. • There is no good solution, but we can pick a better one than
    [Show full text]
  • CSE 486/586 Distributed Systems Remote Procedure Call Recall?
    Recall? App CSE 486/586 Distributed Systems Remote Procedure Call Socket API TCP UDP OS Steve Ko IP Computer Sciences and Engineering University at Buffalo Device Drivers Network Interface CSE 486/586 CSE 486/586 2 Socket API What’s Wrong with Socket API? Server • Low-level read/write socket() • Communication oriented • Same sequence of calls, repeated many times bind() • Etc, etc… Client listen() • Not programmer friendly socket() establish accept() connection connect() block send request write() read() process request send response write() read() CSE 486/586 3 CSE 486/586 4 Another Abstraction RPC • RPC (Remote Procedure Call) • Client • Server – Goal: it should appear that the programmer is calling a local function int main (…) … – Mechanism to enable function calls between different { processes – First proposed in the 80’s … void rpc_call(…) { • Examples rpc_call(…); … – Sun RPC … } – Java RMI – CORBA } • Other examples that borrow the idea … – XML-RPC – Android Bound Services with AIDL – Google Protocol Buffers CSE 486/586 5 CSE 486/586 6 C 1 Local Procedure Call Remote Procedure Call • E.g., x = local_call(“str”); • Give an illusion of doing a local call • The compiler generates coDe to transfer necessary • Closer to the programmers things to local_call – Language-level construct, not OS-level support – Push the parameters to the stack • What are some of the challenges? – Call local_call – How do you know that there are remote calls available? • The compiler also generates coDe to execute the – How do you pass the parameters? local call. – How do you find the correct server process? – Assigns registers – How do you get the return value? – AdJust stack pointers – Saves the return value – Calls the return instruction CSE 486/586 7 CSE 486/586 8 Stub, Marshalling, & Unmarshalling RPC Process • Stub functions: local interface to make it appear that the call is local.
    [Show full text]
  • Remote Procedure Call Protocol
    Remote Procedure Call Protocol Batholomew wish his killdees detains inaccessibly or swaggeringly after Morris rival and screw sartorially, scotopic and lipped. Juanita synthesizes her illuminist ruddily, detoxicant and odious. Toneless Rusty recommence irruptively. Access control to a procedure call machine boundaries has been performed by the major version number represented by procedure call protocol The client can custom this proxy or façade as though we actually implemented these interfaces, although one actually delegates the invocation to the implementation. In dust, an RPC server uses a standard HTTP server on several specific endpoint. The server side is simpler than the client. They provide remote objects to an email below illustrates one final piece to remote procedure call protocol does in a call is allowed to you can infer that can use. You should charge a copy of this. There now be an led even though the offspring was accepted. Determine those data types of fit procedure calling arguments and the result argument. TODO: we pull review the class names and whatnot in color here. IP address of the server that has responded. Because of transport independence, the RPC protocol does he attach specific semantics to three remote procedures or their execution requirements. IP where our office site is hosted. That gross, can a malicious host yeah a message an retransmit it at a hideous time? Rpc calls do a server, or rejected due to do this does a remote procedure parameters as a given server in this strategy for email below illustrates an office with call protocol stacks as this.
    [Show full text]
  • A Fully In-Browser Client and Server Web Application Debug and Test Environment
    LIBERATED: A fully in-browser client and server web application debug and test environment Derrell Lipman University of Massachusetts Lowell Abstract ging and testing the entire application, both frontend and backend, within the browser environment. Once the ap- Traditional web-based client-server application devel- plication is tested, the backend portion of the code can opment has been accomplished in two separate pieces: be moved to the production server where it operates with the frontend portion which runs on the client machine has little, if any, additional debugging. been written in HTML and JavaScript; and the backend portion which runs on the server machine has been writ- 1.1 Typical web application development ten in PHP, ASP.net, or some other “server-side” lan- guage which typically interfaces to a database. The skill There are many skill sets required to implement a sets required for these two pieces are different. modern web application. On the client side, initially, the In this paper, I demonstrate a new methodology user interface must be defined. A visual designer, in con- for web-based client-server application development, in junction with a human-factors engineer, may determine which a simulated server is built into the browser envi- what features should appear in the interface, and how to ronment to run the backend code. This allows the fron- best organize them for ease of use and an attractive de- tend to issue requests to the backend, and the developer sign. to step, using a debugger, directly from frontend code into The language used to write the user interface code is backend code, and to debug and test both the frontend most typically JavaScript [6].
    [Show full text]
  • Ajax Smackdown Dojo Versus YUI
    Ajax Smackdown Dojo versus YUI Struts University Series Ajax Smackdown What is Ajax? Why is it popular now? What can it do for my applications? How do we write Ajax applications? Which library is the best fit for me? What is Ajax? standards-based presentation using XHTML and CSS; dynamic display and interaction using the Document Object Model; data interchange and manipulation using XML and XSLT; asynchronous data retrieval using XMLHttpRequest; and JavaScript binding everything together. How did Ajax Start? Outlook Web Access for Exchange 2000 DHTML version XMLHTTP ActiveX Ships with IE5 Discovered by OddPost, et al XMLHttpRequest (XHR) is now a W3C working draft War: What is it good for? Operating-system independence Microsoft threatened Rapid IE releases "Bugs were pouring into the web at a phenomenal rate" By 2000, Netscape is crushed. Can we give peace a chance? Browser innovation stabilizes AOL disbands Netscape in 2003 MS transfers IE developers to Avalon New computer, new browser February 2005: IE6 83% Mainstream supports XHR MS Way and W3C Way ✗ Ajax AC ✗ Dojo Toolkit ✗ Rico Library ✗ Ajax Client Engine ✗ DOM Drag ✗ RSList Library ✗ AJAX Java Server Faces ✗ Echo 2 ✗ SACK Framework ✗ ICEFaces ✗ Sarissa ✗ AJAX JSP Tag Library ✗ IWF ✗ script.aculo.us ✗ Ajax.NET ✗ JAHAH ✗ SWATO Library ✗ AjaxAspects ✗ Java2Script Pacemaker ✗ Taconite ✗ AjaxCaller ✗ JavaScript GameLib ✗ Tacos Library ✗ AJFormFramework ✗ JPSPAN ✗ ThinkCap JX ✗ AMFPHP ✗ JSMX ✗ Tibet Framework ✗ BackBAse ✗ libXmlRequest Library ✗ WebORB ✗ Bindows ✗ MAJAX Library ✗ WidgetServer
    [Show full text]
  • Introduction to Xml-Rpc, a Simple Xml-Based Rpc Mechanism
    XML-RPC indigoo.com XML-RPC INTRODUCTION TO XML-RPC, A SIMPLE XML-BASED RPC MECHANISM Peter R. Egli INDIGOO.COM 1/11 © Peter R. Egli 2015 Rev. 1.60 XML-RPC indigoo.com Contents 1. What is XML-RPC? 2. XML-RPC architecture 3. XML-RPC protocol 4. XML-RPC server implementation in Java 5. Where to use XML-RPC 2/11 © Peter R. Egli 2015 Rev. 1.60 XML-RPC indigoo.com 1. What is XML-RPC? XML-RPC is a remote procedure call protocol using XML as data format and HTTP as transport protocol. Advantages of XML-RPC: • Simple mechanism to call remote procedures on a machine with a different OS. • XML-RPC is language and platform independent. XML-RPC libraries are available in Java and other languages (e.g. .Net: http://xml-rpc.net/). • XML-RPC is not more than its name implies and thus is very simple and lean (very short specification, see http://xmlrpc.scripting.com/spec.html). Protocols and techniques behind XML-RPC: 1. XML - Formatting of the request and response and the arguments (wire protocol) 2. RPC - Remote call of procedures. 3. HTTP - Transport protocol for the XML („firewall-friendly“). <methodCall> <methodCall> … … XML- </methodCall> </methodCall> XML- RPC HTTP HTTP RPC client server <methodResponse> <methodResponse> … … </methodResponse> </methodResponse> 3/11 © Peter R. Egli 2015 Rev. 1.60 XML-RPC indigoo.com 2. XML-RPC architecture The client application accesses the server through a URL (= location where service resides). The XML-RPC listener receives requests and passes these to the handler (= user defined class servicing the request).
    [Show full text]
  • A Web Interface for 3D Visualization and Interactive Segmentation of Medical Images Hector Jacinto, Razmig Kéchichian, Michel Desvignes, Rémy Prost, Sébastien Valette
    A web interface for 3D visualization and interactive segmentation of medical images Hector Jacinto, Razmig Kéchichian, Michel Desvignes, Rémy Prost, Sébastien Valette To cite this version: Hector Jacinto, Razmig Kéchichian, Michel Desvignes, Rémy Prost, Sébastien Valette. A web in- terface for 3D visualization and interactive segmentation of medical images. 17th International Conference on 3D Web Technology (Web 3D), Aug 2012, Los Angeles, United States. pp.51-58, 10.1145/2338714.2338722. hal-00732335 HAL Id: hal-00732335 https://hal.archives-ouvertes.fr/hal-00732335 Submitted on 14 Sep 2012 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A Web Interface for 3D Visualization and Interactive Segmentation of Medical Images Hector Jacinto∗ Razmig Kechichian´ † Michel Desvignes‡ Remy´ Prost§ Sebastien´ Valette¶ OneFit Medical, SAS CREATIS GIPSA-LAB CREATIS CREATIS CREATIS Figure 1: Our framework enables visualization and processing of large medical images on modest computers. Here, a simple example of lung segmentation is shown. Abstract CR Categories: I.3.2 [Computer Graphics]: Graphic Systems—Remote systems** I.4.6 [Image Processing and We propose a web-accessible image visualization and processing Computer Vision]: Segmentation—Pixel classification; I.3.5 framework well-suited for medical applications.
    [Show full text]
  • Json Remote Procedure Call
    JSONJSON-RPC -RPCindigoo .com JSON REMOTE PROCEDURE CALL OVERVIEW OF JSON-RPC, A VERY SIMPLE AND LIGHTWEIGHT RPC PROTOCOL FOR DISTRIBUTED APPLICATIONS Peter R. Egli INDIGOO.COM1/11 © Peter R. Egli 2015 Rev. 1.60 JSON-RPC indigoo.com Contents 1. What is JSON-RPC? 2. JSON-RPC interactions 3. Transport options for JSON-RPC 4. JSON serialization format 5. JSON-RPC 2.0 examples 6. When to use JSON-RPC 2/11 © Peter R. Egli 2015 Rev. 1.60 JSON-RPC indigoo.com 1. What is JSON-RPC? JSON-RPC is a simple RPC mechanism, similar to XML-RPC. Protocol: Unlike XML-RPC which is a client-server protocol, JSON-RPC is a peer-to-peer protocol. It uses JSON (Javascript Object Notation, RFC4627) as the serialization format and plain TCP streams or HTTP as transport mechanism. JSON message types: JSON-RPC defines 3 message types: Request: Method invokation with arguments encoded in JSON. Response: Reply to method invokation containing the return argument encoded in JSON. Notification: Asynchronous request without response. Specification: JSON-RPC is very simple, i.e. the JSON-RPC specification is very short (ca. 5 pages). See http://json-rpc.org/. 3/11 © Peter R. Egli 2015 Rev. 1.60 JSON-RPC indigoo.com 2. JSON-RPC interactions JSON-RPC defines 2 message exchange patterns that support most of the usual peer2peer interaction schemes. A. Request-Response: The sending JSON peer invokes a method on the remote JSON peer with a JSON request. The remote peer sends back a JSON response message. JSON peer JSON peer Request message: Request (REQ) method Method to be invoked.
    [Show full text]