What is the difference between Document style and RPC style communication

Question

Can somebody explain to me the differences between Document and RPC style webservices  Apart from JAX-RPC  the next version is JAX-WS  which supports both Document and RPC styles   I also understand document style webservices are meant for Asynchronous communication where a client would not block until the response is received   Either way  using JAX-WS I currently annotate the service with  Webservice  generate the WSDL and from that WSDL I generate the client side artifacts   Once the artifacts are received  in both styles  I invoke the method on the port  Now  this does not differ in RPC style and Document style  So what is the difference and where is that difference visible   Similarly  in what way does SOAP over HTTP differ from XML over HTTP  After all SOAP is also XML document with SOAP namespace

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Document  Document style messages can be validated against predefined schema   In document style  SOAP message is sent as a single document   Example of schema      lt types gt        lt xsd schema gt   lt xsd import namespace  http   example com        schemaLocation  http   localhost 8080 ws hello xsd 1   gt        lt  xsd schema gt       lt  types gt    Example of document style soap body message     lt message name  getHelloWorldAsString  gt           lt part name  parameters  element  tns getHelloWorldAsString   gt        lt  message gt      lt message name  getHelloWorldAsStringResponse  gt          lt part name  parameters  gt  element  tns getHelloWorldAsStringResponse   gt        lt  message gt    Document style message is loosely coupled   RPC     RPC style messages use method name and parameters to generate XML structure      messages are difficult to be validated against schema      In RPC style  SOAP message is sent as many elements      lt message name  getHelloWorldAsString  gt       lt part name  arg0  gt  type  xsd string   gt         lt  message gt      lt message name  getHelloWorldAsStringResponse  gt          lt part name  return      gt  type  xsd string   gt        lt  message gt    Here each parameters are discretely specified  RPC style message is tightly coupled  is typically static  requiring changes to the client when the method signature changes The rpc style is limited to very simple XSD types such as String and Integer  and the resulting WSDL will not even have a types section to define and constrain the parameters  Literal By default style  Data is serialized according to a schema  data type not specified in messages but a reference to schema namespace  is used to build soap messages       lt soap body gt        lt myMethod gt           lt x gt 5 lt  x gt           lt y gt 5 0 lt  y gt        lt  myMethod gt      lt  soap body gt    Encoded Datatype specified in each parameter      lt soap body gt        lt myMethod gt            lt x xsi type  xsd int  gt 5 lt  x gt            lt y xsi type  xsd float  gt 5 0 lt  y gt        lt  myMethod gt      lt  soap body gt    Schema free

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I think what you are asking is the difference between RPC Literal  Document Literal and Document Wrapped SOAP web services       Note that Document web services are delineated into literal and wrapped as well and they are different - one of the primary difference is that the latter is BP 1 1 compliant and the former is not   Also  in Document Literal the operation to be invoked is not specified in terms of its name whereas in Wrapped  it is  This  I think  is a significant difference in terms of easily figuring out the operation name that the request is for   In terms of RPC literal versus Document Wrapped  the Document Wrapped request can be easily vetted   validated against the schema in the WSDL - one big advantage   I would suggest using Document Wrapped as the web service type of choice due to its advantages   SOAP on HTTP is the SOAP protocol bound to HTTP as the carrier  SOAP could be over SMTP or XXX as well  SOAP provides a way of interaction between entities  client and servers  for example  and both entities can marshal operation arguments   return values as per the semantics of the protocol   If you were using XML over HTTP  and you can   it is simply understood to be XML payload on HTTP request   response  You would need to provide the framework to marshal   unmarshal  error handling and so on   A detailed tutorial with examples of WSDL and code with emphasis on Java  SOAP and JAX-WS  RPC versus Document Web Services

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An RPC style web service uses the names of the method and its parameters to generate XML structures representing a method   s call stack  Document style indicates the SOAP body contains an XML document which can be validated against pre-defined XML schema document   A good starting point   SOAP Binding  Difference between Document and RPC Style Web Services

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The main scenario where JAX-WS  RPC and Document style are  used as follows    The Remote Procedure Call  RPC  pattern is used when the consumer views the web service as a single logical application or component with encapsulated data  The request and response messages map directly to the input and output parameters of the procedure call    Examples of this type the RPC pattern might include a payment service or a stock quote service  The document-based pattern is used in situations where the consumer views the web service as a longer running business process where the request document represents a complete unit of information  This type of web service may involve human interaction for example as with a credit application request document with a response document containing bids from lending institutions  Because longer running business processes may not be able to return the requested document immediately  the document-based pattern is more commonly found in asynchronous communication architectures  The Document literal variation of SOAP is used to implement the document-based web service pattern

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In WSDL definition  bindings contain operations  here comes style for each operation   Document   In WSDL file  it specifies types details either having inline Or imports XSD document  which describes the structure i e  schema  of the complex data types being exchanged by those service methods which makes loosely coupled  Document style is default      Advantage     Using this Document style  we can validate SOAP messages against predefined schema   It supports xml datatypes and patterns  loosely coupled   Disadvantage  It is a little bit hard to get understand      In WSDL types element looks as follows    lt types gt    lt xsd schema gt     lt xsd import schemaLocation  http   localhost 9999 ws hello xsd 1  namespace  http   ws peter com    gt    lt  xsd schema gt   lt  types gt    The schema is importing from external reference     RPC  In WSDL file  it does not creates types schema  within message elements it defines name and type attributes which makes tightly coupled        lt types  gt     lt message name  getHelloWorldAsString  gt     lt part name  arg0  type  xsd string   gt     lt  message gt     lt message name  getHelloWorldAsStringResponse  gt     lt part name  return  type  xsd string   gt     lt  message gt       Advantage  Easy to understand    Disadvantage     we can not validate SOAP messages     tightly coupled      RPC   No types in WSDL Document  Types section would be available in WSDL

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Can some body explain me the differences between a Document style and   RPC style webservices    There are two communication style models that are used to translate a WSDL binding to a SOAP message body  They are   Document  amp  RPC  The advantage of using a Document style model is that you can structure the SOAP body any way you want it as long as the content of the SOAP message body is any arbitrary XML instance  The Document style is also referred to as Message-Oriented style   However  with an RPC style model  the structure of the SOAP request body must contain both the operation name and the set of method parameters  The RPC style model assumes a specific structure to the XML instance contained in the message body   Furthermore  there are two encoding use models that are used to translate a WSDL binding to a SOAP message  They are   literal  and encoded  When using a literal use model  the body contents should conform to a user-defined XML-schema XSD  structure  The advantage is two-fold  For one  you can validate the message body with the user-defined XML-schema  moreover  you can also transform the message using a transformation language like XSLT   With a  SOAP  encoded use model  the message has to use XSD datatypes  but the structure of the message need not conform to any user-defined XML schema  This makes it difficult to validate the message body or use XSLT based transformations on the message body   The combination of the different style and use models give us four different ways to translate a WSDL binding to a SOAP message   Document literal Document encoded RPC literal RPC encoded   I would recommend that you read this article entitled Which style of WSDL should I use  by Russell Butek which has a nice discussion of the different style and use models to translate a WSDL binding to a SOAP message  and their relative strengths and weaknesses       Once the artifacts are received  in both styles of communication  I   invoke the method on the port  Now  this does not differ in RPC style   and Document style  So what is the difference and where is that   difference visible    The place where you can find the difference is the  RESPONSE    RPC Style    package com sample   import java util ArrayList  import javax jws WebService  import javax jws soap SOAPBinding  import javax jws soap SOAPBinding Style    WebService  SOAPBinding style Style RPC  public interface StockPrice         public String getStockPrice String stockName         public ArrayList getStockPriceList ArrayList stockNameList        The SOAP message for second operation will have empty output and will look like   RPC Style Response    lt ns2 getStockPriceListResponse         xmlns ns2  http   sample com   gt       lt return  gt   lt  ns2 getStockPriceListResponse gt   lt  S Body gt   lt  S Envelope gt    Document Style   package com sample   import java util ArrayList  import javax jws WebService  import javax jws soap SOAPBinding  import javax jws soap SOAPBinding Style    WebService  SOAPBinding style Style DOCUMENT  public interface StockPrice        public String getStockPrice String stockName        public ArrayList getStockPriceList ArrayList stockNameList       If we run the client for the above SEI  the output is   123  123  456   This output shows that ArrayList elements are getting exchanged between the web service and client  This change has been done only by the changing the style attribute of SOAPBinding annotation  The SOAP message for the second method with richer data type is shown below for reference   Document Style Response    lt ns2 getStockPriceListResponse         xmlns ns2  http   sample com   gt   lt return xmlns xsi  http   www w3 org 2001 XMLSchema-instance            xmlns xs  http   www w3 org 2001 XMLSchema          xsi type  xs string  gt 123 lt  return gt   lt return xmlns xsi  http   www w3 org 2001 XMLSchema-instance          xmlns xs  http   www w3 org 2001 XMLSchema          xsi type  xs string  gt 456 lt  return gt   lt  ns2 getStockPriceListResponse gt   lt  S Body gt   lt  S Envelope gt    Conclusion   As you would have noticed in the two SOAP response messages that it is possible to validate the SOAP response message in case of DOCUMENT style but not in RPC style web services  The basic disadvantage of using RPC style is that it doesn   t support richer data types and that of using Document style is that it brings some complexity in the form of XSD for defining the richer data types  The choice of using one out of these depends upon the operation method requirements and the expected clients       Similarly  in what way SOAP over HTTP differ from XML over HTTP  After   all SOAP is also XML document with SOAP namespace  So what is the   difference here    Why do we need a standard like SOAP  By exchanging XML documents over HTTP  two programs can exchange rich  structured information without the introduction of an additional standard such as SOAP to explicitly describe a message envelope format and a way to encode structured content   SOAP provides a standard so that developers do not have to invent a custom XML message format for every service they want to make available  Given the signature of the service method to be invoked  the SOAP specification prescribes an unambiguous XML message format  Any developer familiar with the SOAP specification  working in any programming language  can formulate a correct SOAP XML request for a particular service and understand the response from the service by obtaining the following service details    Service name Method names implemented by the service Method signature of each method Address of the service implementation  expressed as a URI    Using SOAP streamlines the process for exposing an existing software component as a Web service since the method signature of the service identifies the XML document structure used for both the request and the response

[web-services] What is the difference between Document style and RPC style communication?

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