“A Web service is defined by the W3C as a software system designed to support interoperable machine-to-machine interaction over a network. Web services Interview Questions and Answers will guide that these are frequently just Internet application programming interfaces (API) that can be accessed over a network, such as the Internet, and executed on a remote system hosting the requested services. Learn about the Web Services by thousand of web service interview questions and answers”
You should use the <authorization> element to ensure that only authorized users access your Web service. This element allows or denies access to your Web service according to their role.
The EventLog class is used to access the Windows event logs from Windows services. Using EventLog, you can also customize Windows event logs that record information about important software and hardware events, such as the events of the .NET controls, keyboard, or other hardware devices.
The EventLog class allows you to read or write to event logs, delete logs, and create as well as delete event sources. You can use the EventLog class to create event logs while creating an event source. An event source can be used to write to only one event log at a particular time. However, it is possible to associate one event log to multiple sources.
The following are the ways to prevent your Web service from unauthorized access:
★ Using encryption and message-based security.
★ Using authentication and access controls for the Web service.
A Web service may be defined as an independent and self-sustained unit of a software application that is hosted on the Web and implement specific functionalities to execute the business logic. A Web service provides so many functionalities, such as generating pay slips for employees, computing tax, broadcasting weather report, and providing updated news. The Web service allows application to share information or exchange data with other applications across different operating systems and hardware.
Therefore, the work of a Web service is to unite software by exchanging data irrespective of their operating systems, supported hardware, and programming language used in their development. The Web services transfer data in the XML format and use Simple Object Access Protocol (SOAP) to communicate. It is an XML based protocol. The Web services use Web Services Description Language (WSDL) and Universal Description, Discovery, and Integration (UDDI) to describe itself.
The advantages of Web services over COM and DCOM are as follows:
★ Web services are simple to use and can be implemented on varied platforms.
★ Web services are loosely coupled; as a result, their interfaces and methods can be extended.
★ Web services do not carry any state information with them so that multiple requests can be processed simultaneously.
The portType element contains the operations exposed by the Web service, and the messages involved in the communication between the Web service and its consumers.
DISCO is a technology developed by Microsoft to publish and discover Web services. It discovers URLs of all XML Web services located on a Web server and creates a list of these Web services in a file called as a DISCO file.
The two methods to discover the URL of Web services are:
★ Web service discovery tool (Disco.exe)
★ UDDI.
The WebMethod attribute's EnableSession property enables you to enable session state for a Web method.
There are many properties defined in the WebServices class:
★ Application - Obtains the application object for the current HTTP request
★ Context - Obtains the HttpContext object for the current request, which encapsulates all HTTP-specific context used by the HTTP server to process Web requests
★ Server - Obtains the HttpServerUtility object for the current request
★ Session - Obtains the HttpSessionState object for the current request
★ SoapVersion - Obtains the version of the SOAP protocol used to make the SOAP request to a Web service
★ User - Obtains the Server User Object. This property can be used to authenticate whether a user is authorized to execute the request.
The Serialization of the types, such as integers and strings, inside a SOAP message is called encoding. The SOAP objects use XML elements and attributes to serialized data, for example, encodingStyle is an attribute of the Envelop element, which is used to specify the encoding rules for a SOAP object.
A client application uses a .disco file to locate or discover the documents that contain the description of a Web service. The .disco file contains links to other resources, which describe essential features, such as capabilities of a Web service. The links contained in a .disco file can refer to other discovery documents or XSD schemas. The description about the services and capabilities of a Web service is written in Web services Description Language (WSDL). A .disco file can also contain the information about other XML Web services that reside on the same or a different Web server.
The Web services do not have any technique to maintain state. However, it can access ASP.NET objects, such as application and session if they extend from the WebService base class.
The System.Diagnostics is the namespace, which must be included in a code to enable a Web service for writing events in an event log file.
The Installutil.exe tool.
Many people and companies have debated the exact definition of Web services. At a minimum, however, a Web service is any piece of software that makes itself available over the Internet and uses a standardized XML messaging system.
First, a Web service can have a public interface, defined in a common XML grammar. The interface describes all the methods available to clients and specifies the signature for each method. Currently, interface definition is accomplished via the Web Service Description Language (WSDL).
XML is used to encode all communications to a Web service. For example, a client invokes a Web service by sending an XML message, then waits for a corresponding XML response. Because all communication is in XML, Web services are not tied to any one operating system or programming language-Java can talk with Perl; Windows applications can talk with Unix applications.
Second, if you create a Web service, there should be some relatively simple mechanism for you to publish this fact. Likewise, there should be some simple mechanism for interested parties to locate the service and locate its public interface. The most prominent directory of Web services is currently available via UDDI, or Universal Description, Discovery, and Integration.
The Web service protocol stack is an evolving set of protocols used to define, discover, and implement Web services. The core protocol stack consists of four layers:
★ Service Transport
★ XML Messaging
★ Service Discovery
★ Service Description
This layer is responsible for transporting messages between applications. Currently, this includes HTTP, SMTP, FTP, and newer protocols, such as Blocks Extensible Exchange Protocol (BEEP).
This layer is responsible for describing the public interface to a specific Web service. Currently, service description is handled via the WSDL.
This layer is responsible for centralizing services into a common registry, and providing easy publish/find functionality. Currently, service discovery is handled via the UDDI.
Beyond the essentials of XML-RPC, SOAP, WSDL, and UDDI, the Web service protocol stack includes a whole zoo of newer, evolving protocols. These include WSFL (Web Services Flow Language), SOAP-DSIG (SOAP Security Extensions: Digital Signature), and USML (UDDI Search Markup Language). For an overview of these protocols.
rendc.org
Whether it is technological solutions or user-oriented innovations, We have put together for you the best sources of HR Interview Questions and Answers, Tech Ideas, and Programming Tutorials."
Get all the latest information on rendc.org
© 2022 | All rights reserved.
RENDC
welcome to www.rendc.org
