XML / XSLT

What is XML, and why has it gained so much momentum?

XML, or Extensible Markup Language, is an excellent way of representing data in a structured format. The most popular application of XML is for data-exchange. Like HTML, XML is also a textual, tag-based "markup" language. However, unlike HTML, which has a fixed set of tags and focuses on "presentation", XML does not have any fixed set of tags, and XML is all about "data". It is possible to create our own tags, and write data inside these tags in an XML document. The XML data is structured in a hierarchical format, and there are many "parsers" available that allow easily getting to the data values. In addition to data-exchange, XML is being used for various other purposes, such as content management, XML-based configuration files, eBusiness, document publishing, application integration, and most notably XML-based messaging or Web services.

Some of the reasons behind XML's success include: • The ability to define and use our own tags makes XML "extensible", and self-describing. • XML's textual nature makes it highly portable allowing us to send and receive data from one platform to the other without any issues (such as encoding). • The availability of many free XML parsers and processors, makes it really easy to create, read, and manage XML documents. • As mentioned earlier, XML is all about data. Separating "presentation" from the actual "content" has many benefits, including the flexibility of providing/presenting data to multiple destinations/devices. • The availability of various other standards surrounding the XML (such as XSLT, XPath, and XML Schema); and support for these standards in various toolkits/APIs. • XML is the "standard" backed by W3C and supported by major vendors.
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Defines XML acronym correctly with two or more characteristics. States at least two of the success reasons.

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Defines XML acronym correctly with at least one characteristic. States at least one success reason.

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Defines XML acronym correctly, but provides no other information.

What is the difference between well-formed and valid XML document?

W3C, in the XML specification, has defined certain rules that need to be followed while creating XML documents. The examples of such rules include: having exactly one root element, proper nesting (XML elements must be closed in the order they are opened), having end-tag for each start- tag, using single/double quotes for attribute values, and so on. If an XML document follows all these rules, it is said to be well-formed document and XML parsers can be used to parse and process such documents.

Document Type Definitions (DTDs) or XML Schemas can be used to define the structure and content of a specific class of XML documents. This includes the parent-child relationship details, attribute lists, data type information, value restrictions, etc. In addition to the well-formedness rules, if an XML document also follows the rules specified in the associated DTD/Schema, it is said to be a valid XML document. All valid XML documents are well-formed; but the reverse is not always true, that is, well-formed XML documents do not necessarily have to be valid.

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States at least two of the well-formed rules. States both rules of validity.

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States at least one of the well-formed rules. States at least one rule of validity.

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What is the use of Namespaces in XML?

As XML does not predefine any set of tags/attribute names. Hence, it is quite possible that two totally different XML documents, defined by two totally different people/ companies, use the same tag name/attribute name. If an application needs to use (merge, process, etc.) above two XML documents together, this would cause confusion and we need a way to distinguish deterministically between tags with the same name. XML Namespaces are used for this purpose. Namespaces are defined using URI (Uniform Resource Identifier), and then associated with the element/attribute names. Namespaces are also used to "group" a logically related set of XML vocabulary.

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States that a namespace distinguishes uniqueness in naming for one document and discusses URI.

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States that a namespace distinguishes uniqueness in naming for one document.

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What is XPath?

XML Path Language (XPath) is a W3C specification that defines syntax for addressing parts of XML document. XML document is considered as a logical tree structure, and syntax based on this consideration is used to address elements and attributes at any level in the XML document.

What is XSLT? And what's its use?

XSL Transformations (XSLT) is yet another popular W3C specification that defines XML-based syntax, used to transform XML documents to any other text format, such as HTML, text, XML, etc.

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Correctly defines what acronym stands for and that it involves transformation of XML documents.

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Correctly defines what acronym stands for.

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How are DTDs/XML Schemas important while building XML applications?

Document Type Definition (DTD) or XML Schema is used to define the structure and other constrains for the XML documents. If an XML document has an associated DTD/Schema, it is said to be a valid XML document, and it ensures that the XML document structure and data adheres to the predefined rules. While using the XML document in an application, once the XML document is validated, it is then not required to assert/check for parent-child relationship, presence/absence of elements/attributes, data-value range checks, etc. The schema validation already took care of all such issues.

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Correctly defines what acronym stands for and that it involves the definition of the structure of an XML document.

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Correctly defines what acronym stands for.

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What are the xerces and xalan apis used for?

Xerces is an XML parser for reading and/or querying XML documents and provides the ability to either sequentially process an XML file or treat an XML file much like a database table. It implements Document Object Model (DOM) and Simple Application Programming Interface for XML (SAX). (I.E. Xerces is an XML parser)
Xalan is an XSLT processor for transforming XML documents into HTML, text, or other XML document types. It implements XSL Transformations (XSLT) and XML Path Language (Xpath). Xalan uses Xerces as its input stage. (I.E. Xalan is an XML transformer, or stylesheet processor api)

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Correctly defines both Xerces and Xalan.

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Correctly defines either Xerces or Xalan.

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What are the reasons to use DOM or SAX, or both?

• Use SAX for low-level XML processing. The SAX parse API is very fast, but difficult to use. SAX is useful when huge amounts of XML need to be processed, but the information needed is highly local, meaning only a small amount of data needs to be stored. This is usually the case in transforming linear documents, where little cross-linking occurs. • Use DOM when you need the whole document in memory. The DOM is a quite convenient way to access and manipulate XML data. The building of a large DOM tree is a heavy task, but you get access to the whole information of a document. DOM scalability is limited by the computer's memory. The underlying XML needs to be fully parsed before DOM processing can occur. • The mixing of SAX and DOM is the right compromise in many cases.

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Correctly defines the uses of both SAX and DOM.

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Correctly defines the uses of either SAX or DOM.

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Using XSLT, how would you extract a specific attribute from an element in an XML document?

This is one of the most basic applications of XSLT. They should construct a reply similar to the example below, or at least be able to identify the components necessary for this operation: xsl:template to match the appropriate XML element, xsl:value-of to select the attribute value, and the optional xsl:apply-templates to continue processing the document. Attribute Value:

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They should construct a reply similar to the example below, or at least be able to identify the components necessary for this operation: xsl:template to match the appropriate XML element, xsl:value-of to select the attribute value, and the optional xsl:apply-templates to continue processing the document

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Identifies at least one of the components.

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Apache Tomcat

What is the significance of the WEB-INF folder in the implementation of the Apache Tomcat web server?

The WEB-INF folder serves in the “bootstrapping” process, whereby the web server can load all jars and class files dynamically, rather than requiring all classes to be jarred and the jar names placed in the system classpath.

Java

What is the argument type of a program’s main method?

A string array.

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A String array.

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An array.

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What is the difference between a constructor method and a method?

The constructor method is automatically invoked when an object is instantiated, all other methods must be called explicitly.

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The constructor method is automatically invoked when an object is instantiated, all other methods must be called explicitly.

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Describes either the constructor or the method.

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What is an interface and what is its use?
Interfaces are classes which may contain a method’s signature only but not bodies. Methods declared in interface are abstract methods. We can implement many interfaces on a class which support the multiple inheritance.
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Interfaces are classes which may contain a method’s signature only but not bodies. Methods declared in interface are abstract methods. We can implement many interfaces on a class which support the multiple inheritance.

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Describes either that the methods cannot have bodies or that the methods are abstract or the inheritance aspect.

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What is the difference between an interface and an abstract class?

All the methods declared inside an interface are abstract, whereas abstract classes must have at least one abstract method and other methods may be concrete or abstract. In an interface we need not use the keyword abstract for the methods.

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All the methods declared inside an interface are abstract, whereas abstract classes must have at least one abstract method and other methods may be concrete or abstract. In an interface we need not use the keyword abstract for the methods.

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Describes either that the methods of an interface are abstract or that the methods in an abstract class can be either abstract or concrete.

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What are the arguments and types for an implementation of the doPost and doGet methods of javax.servlet.http.HttpServlet?

(HttpServletRequest req, HttpServletResponse resp)

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Describes HttpServletRequest as the request and HttpServletResponse as the response.

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Describes request and response.

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What methods have you utilized to maintain state between page submissions in a web application architecture?

I would expect to hear something about serialization or session usage.

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Describes both serialization and session usage.

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Describes either serialization or session usage.

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What are the steps in establishing a JDBC connection?

1. Loading the driver. 2. Making the connection.

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Describes both steps.

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Describes one step.

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What are the different types of SQL Statement Objects and what connection methods do you use to create them?

1. Statement (use createStatement method)
2. Prepared Statement (use prepareStatement method)
3. Callable Statement (use prepareCall method)

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Describes at least two types.

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Describes one type.

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Velocity Templates

What is the correct syntax for referencing a variable?

Variables are referenced by their name preceded by a dollar sign.

What syntax would you use to test for an empty variable?

#if ($VARNAME.length() == 0)
(you can use most string function/methods within velocity)

What syntax would you use to test for the presence of a variable?

#if ( $ENDNUM ) wil return true if variable ENDNUM exists
#if ( ! $ENDNUM ) will return true if variable ENDNUM does not exist

Can you access java classes in Velocity?

Yes

How would you code an iterative process?

With a for loop. Here is an example:

#foreach ($jsFile in $JSSource)
#include($jsFile)
#end

How would you code a conditional process?

With an if construct. Here is an example:

#if($OTHERACCT=="multiple")

ATTENTION!  This customer has more than one active account.  This is a serious error.  Please contact the Trust Fund Officer for assistance in correcting this error.

#end

Does Velocity support embedded templates?

Yes.

HTML / Javascript / CSS

Why should you not include javascript on a page where it will never be used?

All javascript on a page is pre-validated at page load time by the browser using the JavaScript interpreter. As the browser loads your script, it performs a myriad of checks for basic language problems. If, for instance, you leave off the closing half of a pair of parentheses, the interpreter will tell you about it in the form of a load-time error. Why? Because a script can't run until it has loaded successfully.

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Fully describes javascript processing and why uneeded scripts should be removed.

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What are the HTML tags related to a table?

- table - table caption - table heading - table row - table cell

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Describes at least three of the tags.

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Describes at least one of the tags.

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How do you achieve the effect of having the enter key submit a form using Javascript?

By detecting the keypress or keydown event, you can interrogate the value of the key pressed, and if the value matches that of the enter key, then you can execute a method that submits the page form.

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By detecting the keypress or keydown event, you can interrogate the value of the key pressed, and if the value matches that of the enter key, then you can execute a method that submits the page form.

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Describes either key detection or method execution.

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How do you force the cursor to appear in a specific form field on a page when it is first rendered?

By specifying that the form field be given focus with the onLoad attribute on the body tag:

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Describes the body tag and the onLoad attribute.

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Describes the body tag.

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Swing/SWT/AWT

What is JNLP and what is its significance in Swing application programming?

JNLP stands for Java Network Launch Protocol and is a Java protocol to allow remote Java Swing based applications to be downloaded and run on a client machine. All necessary class files, images, etc, can be downloaded, and do not need to be present on the client machine beforehand. A JNLP application is described by a JNLP file, which is an XML document. Typically, this document will be downloaded by a Web browser. The browser itself will not know what to do with this file, so it will pass it to a "JNLP helper" to deal with. The JNLP helper will read the list of resources required and download them if necessary. It will also check that all constraints such as version of the Java runtime are satisfied. Once this is all done, the helper will start the Java application running.

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Defines the JNLP acronym and describes the client side loading of the application elements clearly.

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Defines the JNLP acronym.

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Describe several different types of swing layout managers. • BorderLayout - A BorderLayout places components in up to five areas: top, bottom, left, right, and center. All extra space is placed in the center area. • BoxLayout - The BoxLayout class puts components in a single row or column. It respects the components' requested maximum sizes and also lets you align components. • CardLayout - The CardLayout class lets you implement an area that contains different components at different times. A CardLayout is often controlled by a combo box, with the state of the combo box determining which panel (group of components) the CardLayout displays. • FlowLayout - FlowLayout is the default layout manager for every JPanel. It simply lays out components in a single row, starting a new row if its container isn't sufficiently wide. • GridBagLayout - GridBagLayout is a sophisticated, flexible layout manager. It aligns components by placing them within a grid of cells, allowing some components to span more than one cell. The rows in the grid can have different heights, and grid columns can have different widths. • GridLayout - GridLayout simply makes a bunch of components equal in size and displays them in the requested number of rows and columns. • SpringLayout - SpringLayout is a flexible layout manager designed for use by GUI builders. It lets you specify precise relationships between the edges of components under its control.
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Describes at least three of the seven layout managers.

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Describes one layout manager.

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Messaging/Middleware

What message queuing middleware do you have experience with, and what case can you make for or against its use?

I would expect to hear about MQ Series, MSMQ, or TIB/Rendevous

Aguments For: • connect different systems without having, necessarily, to redevelop existing applications • decouple what have hitherto been insurmountable systems dependencies (for example overcoming the inherent blocking found in Remote Procedure Calls (RPCs) • provide implicit transaction integrity (because writing to/from queues and between queues can, in some systems, be deemed to be robust) • increase application throughput without sacrificing user response times

Arguments Against: • communications are asynchronous, therefore applications that require immediate feedback on the success of the transaction cannot obtain that feedback • infrastructure investment for messaging server

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Describes experience in at least one of the message queuing middleware packages and provides at least one argument for and one argument against.

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Describes experience in at least one of the message queuing middleware package.

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Names a message queuing middleware package but describes no experience or arguments for or against.
Service Oriented Architectures (SOAs)

Define messaging protocols SOAP and RMI/IIOP as they relate to service oriented architectures and provide some reasons for and against their use.

SOAP - SOAP (Simple Object Access Protocol) is a lightweight XML-based messaging protocol used to encode the information in web service request and response messages before sending them over a network. SOAP messages are independent of any operating system or protocol and may be transported using a variety of internet protocols, including SMTP, MIME and HTTP. Since web protocols are installed and available for use by all major operating system platforms, HTTP and XML provide an already at-hand solution to the problem of how programs running under different operating systems in a network can communicate with each other. SOAP specifies exactly how to encode an HTTP header and an XML file so that a program in one computer can call a program in another computer and pass it information. It also specifies how the called program can return a response. It's based on remote procedure calls, or RPC.

RMI/IIOP - Remote Method Invocation (RMI) is the standard for distributed object computing in Java. RMI enables an application to obtain a reference to an object that exists elsewhere in the network, and then invoke methods on that object as though it existed locally in the client's virtual machine. Remote Method Invocation (RMI) over Internet Interop-Orb-Protocol (IIOP) combines the RMI with Common Object Request Broker Architecture (CORBA) technology. Like CORBA, RMI over IIOP is based on open standards defined with the participation of hundreds of vendors and users in the Object Management Group. Like CORBA, RMI over IIOP uses IIOP as its communication protocol. IIOP eases legacy application and platform integration by allowing application components written in C++, Smalltalk, and other CORBA supported languages to communicate with components running on the Java platform.

SOAP
Pros
• An advantage of SOAP is that program calls are much more likely to get through firewall servers that screen out requests other than those for known applications (through the designated port mechanism). Since HTTP requests are usually allowed through firewalls, programs using SOAP to communicate can be sure that they can communicate with programs anywhere. • Provides the ability to use any development language for the client-side and server-side • SOAP offers a much easier means of messaging and communication than does RMI and RPC. Additionally, the encoding it provides for XML is handy. SOAP not only adds messaging to your toolbox, but also removes the burden of having to parse XML with tools that may not be as mature as their Java counterparts. • Remote objects can give a program almost unlimited power over the Internet, but most firewalls block non-HTTP requests. SOAP, an XML-based protocol, gets around this limitation to provide intraprocess communication across machines.
Cons
• Overhead involved in parsing XML at either end.

RMI/IIOP
Pros
• If you're a Java programmer, you've got RMI right there as part of the Java API -- and it is easily accessible and well documented
Cons
• Requires the serialization of objects into a binary transmission which is performance intensive • Locks you into using Java as your client-side development platform • Prohibits the use of messaging middleware because the communication is based on Java Objects, whereas messaging middleware typically requires the communication to be text-based. • Remote objects can give a program almost unlimited power over the Internet, but most firewalls block non-HTTP requests. SOAP, an XML-based protocol, gets around this limitation to provide intraprocess communication across machines. • Since most firewalls block all but a few ports, such as the standard HTTP port 80, all of today's distributed object protocols like RMI suffer because they rely on dynamically assigned ports for remote method invocations. This results in an insecure firewall configuration that is typically unacceptable in today’s security conscious business climate.

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Correctly defines SOAP and RMI/IIOP and provides at least one argument for and against each.

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Correctly defines either SOAP or RMI/IIOP.

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