Saturday, April 23, 2011

Few ways to improve the performance of your Java code

In the following post, I have shown several ways to improve the performance in your Java code. 


Appending string values in a loop


BAD
  String s = "";
  for (int i = 0; i < field.length; i++) {
    s = s + field[i];
  }

GOOD 
  StringBuffer buf = new StringBuffer();
  for (int i = 0; i < field.length; i++) {
    buf.append(field[i]);
  }
  String s = buf.toString();

When concatenating string in a loop, In each iteration, the String is converted to a StringBuffer/StringBuilder, appended to, and converted back to a String. these addtional cost can be avoided by directly using the second approach. 



Creating instance of  Integer,Long, Short, Character, and Byte

Using new Integer(int) is guaranteed to always result in a new object whereas Integer.valueOf(int) allows caching of values to be done by the compiler, class library, or JVM. Using of cached values avoids object allocation and the code will be faster.

Therefore Integer.valueOf(int) is better than using new Integer(int);
This is same for others (Long,Short,Character and Byte)



Accessing values in a Map.

BAD
for (Object key: map.keySet()){
    doSomething(map.get(key));
}
GOOD
for (Map.Entry entry: map.entrySet()){
    doSomething(entry.getValue());
}
It is more efficient to use an iterator on the entrySet of the map than using the keySet, to avoid the Map.get(key) lookup.

Saturday, April 16, 2011

WSDL to UDDI Mapping





Introduction


Universal Description, Discovery and Integration (UDDI) is a platform independent, Extensible Markup Language (XML) based registry and it provides a mechanism for describing and discovering Web service providers, Web services and technical interfaces which may be used to access those services. There are several UDDI implementations are available (Apache jUDDI [1], OpenUDDI Server etc.). The Web Services Description Language (WSDL) is an XML based language for describing the interface, protocol bindings, and the deployment details of network services. The objective of this blog is to show the relationship between WSDL and UDDI and to describe a mechanism for mapping WSDL service descriptions to the UDDI data structures.The information in this blog adheres to the procedures outlined in OASIS UDDI Technical Note [2] and is consistent with the UDDI Version 3.0.2 Specification [3].

 



How to invoke a service using UDDI registry


UDDI is designed to be interrogated by SOAP messages and to provide access to WSDL documents describing service binding information required to interact with the web services listed in the registry.
Add caption





The steps involved in providing and consuming a service are:

  1. A service provider (business) describes its service using WSDL. This definition is published to a UDDI registry.
  2. A service consumer lookup the service in the UDDI registry and receives service binding information that can be used to determine how to communicate with that service.
  3. The client then uses the binding information to invoke the service.




    How to Map WSDL Document in UDDI.


    This mapping describe a methodology to map WSDL 1.1 documents to UDDI version 3. Before going into details of mapping, it is important to understand the UDDI data structures. Here I have briefly described the data structures in UDDI.


    UDDI data structures


    • businessEntity - A businessEntity structure used to represent the business or service provider within UDDI.
    • businessService - A businessService structure used to represent a web service. A businessEntity can have several businessServices.
    • bindingTemplate - A binding template contains the technical information associated to a particular service. A businessService can have several bindingTemplates
    • Technical Model (tModel) - A tModel is a generic container of information where designers can write any technical information associated for using the Web service.


    WSDL portType to tModel Mapping


    The information represent about a WSDL portType by the UDDI tModel is its entity type, local name, namespace, and location of the WSDL document that defines the portType. Each WSDL portType maps to a UDDI tModel having the same name as local name of the portType in the WSDL. The overviewURL provides the location of the WSDL document. In addition to that tModel contains a category bag with keyedReferences for type categorization as “portType” and namespace of the portType (If the wsdl:portType has a targetNamespace).


    Following is the structure of UDDI portType tModel

    <tModel tModelKey="uuid:e8cf1163-8234-4b35-865f-94a7322e40c3">
    <name>
        [WSDL portType local name]
    </name>
    <overviewDoc>
        <overviewURL useType=”wsdlInterface>
            [WSDL location URL]
        </overviewURL>
    </overviewDoc>
    <categoryBag>
        <keyedReference
                tModelKey="uddi:uddi.org:xml:namespace"
                keyName="portType namespace"
                keyValue="[WSDL namespace]"/>
        <keyedReference
                tModelKey="uddi:uddi.org:wsdl:types"
                keyName="WSDL type"
                keyValue="portType"/>
    </categoryBag>
    </tModel>


    WSDL binding to tModel Mapping



    The information represent about a WSDL binding by the UDDI tModel is its entity type, local name, namespace, the location of the WSDL document that defines the binding, the portType that it implements, protocol, and optionally the transport information. Each WSDL binding maps to a UDDI tModel having same name as local name of the binding in the WSDL. The overviewURL provides the location of the WSDL document. In addition to that tModel contains a category bag with following keyedReferences


    • namespace of the binding (If the wsdl:binding has a targetNamespace).
    • type categorization as “binding”
    • binding characterized as type "wsdlSpec".
    • portType reference for wsdl:portType to which the wsdl:binding relates.
    • protocol categorization
    • transport categorization


      Following is the structure of UDDI binding tModel


      <tModel tModelKey="uuid:49662926-f4a5-4ba5-b8d0-32ab388dadda">
      <name>
          [WSDL binding local name]
      </name>
      <overviewDoc>
          <overviewURL useType=”wsdlInterface>
              [WSDL location URL]
          </overviewURL>
      </overviewDoc>
      <categoryBag>
          <keyedReference
                  tModelKey="uddi:uddi.org:xml:namespace"
                  keyName="binding namespace"
                  keyValue="[WSDL namespace]"/>
          <keyedReference
                  tModelKey="uddi:uddi.org:wsdl:types"
                  keyName="WSDL type"
                  keyValue="binding"/>
          <keyedReference
                  tModelKey="uddi:uddi.org:categorization:types"
                  keyName="uddi-org:types"
                  keyValue="wsdlSpec"/>
          <keyedReference
                  tModelKey="uddi:uddi.org:wsdl:porttypereference"
                  keyName="portType reference"
                  keyValue="[tModel key of the PortType]"/>
          <keyedReference
                  tModelKey="uddi:uddi.org:wsdl:categorization:protocol"
                  keyName="[Protocol supported by the binding]"
         keyValue= "[tModel key of the Protocol tModel]" />
          <keyedReference
                  tModelKey="uddi:uddi.org:wsdl:categorization:transportport"
                  keyName="[Transport]"
           keyValue="[tModel key of the Transport tModel]" />
      </categoryBag>
      </tModel>


      WSDL port to UDDI bindingTemplate Mapping



      A WSDL port maps to a bindingTemplate. The information represent about a WSDL port by the UDDI bindingTemplate is the binding that it implements, the portType that it implements, local name of the port and access point of the service. The bindingTemplate has tModelInstanceDetails element which contain the following tModelInstanceInfo elements.


      • tModelInstanceInfo with a tModelKey of the tModel corresponding to the binding that port implements. The instanceParms represent wsdl:port local name.
      • A tModelInstanceInfo with a tModelKey of the tModel corresponding to the portType that port implements.
      • The accessPoint is set from the location attribute on the extension element that is associated with the port element.


      WSDL service to UDDI businessService Mapping


      A WSDL service maps to a businessService. The information represent about a service by the UDDI businessService is its entity type, local name, namespace, and the list of ports that it supports. The name of the businessService can be represented by the local name of the service in the WSDL. In addition to that businessService contains a category bag with following keyedReferences
        • namespace of the service
        • local name of the service
        • type categorization as “service”

      Following is the structure of UDDI businessService and bindingTemplate

      <businessService
              serviceKey="102b114a-52e0-4af4-a292-02700da543d4"
              businessKey=[businessKey of the bussinessEntity which this service belongs]>
          <name>[Service local name]</name>
          <bindingTemplates>
              <!--WSDL port maps to a bindingTemplate-->
              <!--1 or more repetitions-->
              <bindingTemplate
                      bindingKey="f793c521-0daf-434c-8700-0e32da232e74"
                      serviceKey="102b114a-52e0-4af4-a292-02700da543d4">
                  <accessPoint useType="endpoint">
                      [EndPoint URL]
                  </accessPoint>
                  <tModelInstanceDetails>
                      <!-- TModelInstanceInfo indicating the binding-->
                      <tModelInstanceInfo
                              tModelKey=[tModel key of the binding tModel]>
                          <description xml:lang="en">
                              The wsdl:binding that this wsdl:port implements. The instanceParms specifies the port local name.
                          </description>
                          <instanceDetails>
                              <instanceParms>[WSDL port local name]</instanceParms>
                          </instanceDetails>
                      </tModelInstanceInfo>
                      <!--TModelInstanceInfo indicating portType -->
                      <tModelInstanceInfo
                              tModelKey=[tModel key of the portType tModel]>
                          <description xml:lang="en">
                              The wsdl:portType that this wsdl:port implements
                          </description>
                      </tModelInstanceInfo>
                  </tModelInstanceDetails>
              </bindingTemplate>
          </bindingTemplates>
          <categoryBag>
              <keyedReference
                      tModelKey="uddi:uddi.org:xml:namespace"
                      keyName="service namespace"
                      keyValue="[Service namespace Value]"/>
              <keyedReference
                      tModelKey="uddi:uddi.org:xml:localname"
                      keyName="service local name"
                      keyValue="[Service local name value]"/>
              <keyedReference
                      tModelKey="uddi:uddi.org:wsdl:types"
                      keyName="WSDL type"
                      keyValue="service"/>
          </categoryBag>
      </businessService>

      Summary


      • WSDL portType element is mapped to a UDDI tModel
      • WSDL binding element is mapped to a UDDI tModel.
      • WSDL port element is mapped to a UDDI bindingTemplate which has information about the WSDL binding and the WSDL portType implemented by port.
      • Finally WSDL service element is mapped to a UDDI businessService.


      This blog post has shown how to map WSDL document to the UDDI registry using the approach described in the OASIS UDDI Technical Note[2] also it adheres to the UDDI Version 3.0.2 Specification [3]

      References