Interview Questions & Answers

XML-RPC is a protocol that uses XML messages to perform Remote Procedure Calls. Requests are encoded in XML and sent via HTTP POST; XML responses are embedded in the body of the HTTP response. More succinctly, XML-RPC = HTTP + XML + Remote Procedure Calls. Because XML-RPC is platform independent, diverse applications can communicate with one another. For example, a Java client can speak XML-RPC to a Perl server. To get a quick sense of XML-RPC, here is a sample XML-RPC request to a weather service (with the HTTP Headers omitted): <?xml version="1.0"...

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: 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). XML Messaging: This layer is responsible for encoding messages in a common XML format so that messages can be understood at either end. Currently, this includes XML-RPC and...

If you want a more intuitive feel for Web services, try out the IBM Web Services Browser, available on the IBM Alphaworks site. The browser provides a series of Web services demonstrations. Behind the scenes, it ties together SOAP, WSDL, and UDDI to provide a simple plug-and-play interface for finding and invoking Web services. For example, you can find a stock-quote service, a traffic-report service, and a weather service. Each service is independent, and you can stack services like building blocks. You can, therefore, create a single page...

A web service is any piece of software that makes itself available over the Internet and uses a standardized XML messaging system. 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. Beyond this basic definition, a Web service...

403 Forbidden is the HTTP status code produced by a web server when you are not permitted to access a particular URL. Usually a 403 Forbidden error means that the page in question does exist but cannot be accessed by you. Some websites are locked down so that only those on the local company or school network can access parts of the site. You will often see 403 Forbidden errors when browsing such sites from "off-campus." Sometimes webmasters try to set up dynamic web programming features like PHP or Perl/CGI but fail to do so correctly....

Every time you follow a link or type in the name of a website, such as www.scriptscart.com, that name must be translated into an IP address on the Internet. This translation is done by the domain name system. A DNS server is a program that participates in the task of providing this service. Some DNS servers respond to queries from web browsers and other programs, make further inquiries, and return IP addresses, such as 208.27.35.236. Other DNS servers have primary responsibility for answering DNS inquiries about names within a particular domain,...

SSL (Secure Sockets Layer), also known as TLS (Transport Layer Security), is a protocol that allows two programs to communicate with each other in a secure way. Like TCP/IP, SSL allows programs to create "sockets," endpoints for communication, and make connections between those sockets. But SSL, which is built on top of TCP, adds the additional capability of encryption. The HTTPS protocol spoken by web browsers when communicating with secure sites is simply the usual World Wide Web HTTP protocol, "spoken" over SSL instead of directly over...

A web browser is what you're probably looking at right now: a program on yourcomputer that shows you stuff that's on the web. A web server is a program on a server computer, somewhere out on the Internet, that delivers web pages to web browsers. The term web server also refers to an actual, physical computer that is running web server softwa...

A web server is a computer program that delivers (serves) content, such as web pages, using the Hypertext Transfer Protocol (HTTP), over the World Wide Web. The term web server can also refer to the computer or virtual machine running the program. In large commercial deployments, a server computer running a web server can be rack-mounted with other servers to operate a web farm. The primary function of a web server is to deliver web pages to clients. This means delivery of HTML documents and any additional content that may be included by...

.htaccess is an extension of the Directory Hierarchy that serves to enable users to set directives for themselves, subject to permissions (AllowOverride) set up by the server administrat...