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    16Jan, 2012
    Server Application Development

    Server Application Development

    Server-side applications in the managed world are implemented through runtime hosts. Unmanaged applications host the common language runtime which allows your custom managed code to control the behavior of the server. This model provides you with all the features of the common language runtime and class library while gaining the performance and scalability of the host server.
    The following illustration shows a basic network schema with managed code running in different server environments. Servers such as the Microsoft Internet Information Server (IIS) and the Microsoft SQL Server (MS-SQL) can perform standard operations while your application logic executes through the managed code.

    Server-side managed code

    ASP.NET is the hosting environment that enables developers to use the .NET Framework to target Web-based applications. However, ASP.NET is more than just a runtime host; it is a complete architecture for developing Web sites and Internet-distributed objects using managed code. Both Web Forms and XML Web services use IIS and ASP.NET as the publishing mechanism for applications, and both have a collection of supporting classes in the .NET Framework.
    XML Web services, an important evolution in Web-based technology, are distributed, server-side application components similar to common Web sites. However, unlike Web-based applications, XML Web services components have no UI and are not targeted for browsers such as Internet Explorer and Netscape Navigator. Instead, XML Web services consist of reusable software components designed to be consumed by other applications, such as traditional client applications, Web-based applications, or even other XML Web services. As a result, XML Web services technology is rapidly moving application development and deployment into the highly distributed environment of the Internet.
    If you have used earlier versions of the ASP technology, you will immediately notice the improvements that ASP.NET and Web Forms offer. For example, you can develop Web Forms pages in any language that supports the .NET Framework. In addition, your code no longer needs to share the same file with your HTTP text (although it can continue to do so if you prefer).
    Web Forms pages execute in native machine language because, like any other managed application, they take full advantage of the runtime. In contrast, unmanaged ASP pages are always scripted and interpreted.
    ASP.NET pages are faster, more functional, and easier to develop than unmanaged ASP pages because they interact with the runtime like any managed application. The .NET Framework also provides a collection of classes and tools to aid in development and consumption of XML Web services applications. XML Web services are built on standards such as SOAP (a remote procedure-call protocol), XML (an extensible data format), and WSDL ( the Web Services Description Language). The .NET Framework is built on these standards to promote interoperability with non-Microsoft solutions.
    For example: the Web Services Description Language tool included with the .NET Framework SDK can query an XML Web service published on the Web, parse its WSDL description, and produce C# or Visual Basic source code that your application can use to become a client of the XML Web service. The source code can create classes derived from classes in the class library that handle all the underlying communication using SOAP and XML parsing. Although you can use the class library to consume XML Web services directly, the Web Services Description Language tool and the other tools contained in the SDK facilitate your development efforts with the .NET Framework.
    If you develop and publish your own XML Web service, the .NET Framework provides a set of classes that conform to all the underlying communication standards, such as SOAP, WSDL, and XML. Using those classes enables you to focus on the logic of your service, without concerning yourself with the communications infrastructure required by distributed software development.
    Finally, like Web Forms pages in the managed environment, your XML Web service will run with the speed of native machine language using the scalable communication of the Microsoft Internet Information Server (IIS).

    16Jan, 2012
    Client Application Development

    Client Application Development

    Client applications are the closest to a traditional style of application in Windows-based programming. These are the types of applications that display windows or forms on the desktop, enabling a user to perform a task. Client applications include applications such as word processors and spreadsheets, as well as custom business applications such as data-entry tools, reporting tools, and so on. Client applications usually employ windows, menus, buttons, and other GUI elements, and they likely access local resources such as the file system and peripherals such as printers.
    Another kind of client application is the traditional ActiveX control (now replaced by the managed Windows Forms control) deployed over the Internet as a Web page. This application is much like other client applications: it is executed natively, has access to local resources, and includes graphical elements.
    In the past, developers created such applications using C/C++ in conjunction with the Microsoft Foundation Classes (MFC) or with a rapid application development (RAD) environment such as Microsoft® Visual Basic®. The .NET Framework incorporates aspects of these existing products into a single, consistent development environment that drastically simplifies the development of client applications.
    The Windows Forms classes contained in the .NET Framework are designed to be used for GUI development. You can easily create command windows, buttons, menus, toolbars, and other screen elements with the flexibility necessary to accommodate shifting business needs.
    For example, the .NET Framework provides simple properties to adjust visual attributes associated with forms. In some cases the underlying operating system does not support changing these attributes directly, and in these cases the .NET Framework automatically recreates the forms. This is one of many ways in which the .NET Framework integrates the developer interface, making coding simpler and more consistent.
    Unlike ActiveX controls, Windows Forms controls have semi-trusted access to a user’s computer. This means that binary or natively executing code can access some of the resources on the user’s system (such as GUI elements and limited file access) without being able to access or compromise other resources. Because of code access security, many applications that once needed to be installed on a user’s system can now be deployed through the Web. Your applications can implement the features of a local application while being deployed like a Web page.

    16Jan, 2012
    .NET Framework Class Library

    .NET Framework Class Library

    The .NET Framework class library is a collection of reusable types that tightly integrate with the common language runtime (CLR). The class library is object oriented, providing types from which your own managed code can derive functionality. This not only makes the .NET Framework types easy to use, but also reduces the time associated with learning new features of the .NET Framework. In addition, third-party components can integrate seamlessly with classes in the .NET Framework.
    For example, the .NET Framework collection classes implement a set of interfaces that you can use to develop your own collection classes. Your collection classes will blend seamlessly with the classes in the .NET Framework.
    As you would expect from an object-oriented class library, the .NET Framework types enable you to accomplish a range of common programming tasks, including tasks such as string management, data collection, database connectivity, and file access. In addition to these common tasks, the class library includes types that support a variety of specialized development scenarios. For example, you can use the .NET Framework to develop the following types of applications and services:

    • Console applications.
    • Windows GUI applications (Windows Forms).
    • ASP.NET applications.
    • XML Web services.
    • Windows services.

    For example, the Windows Forms classes are a comprehensive set of reusable types that vastly simplify Windows GUI development. If you write an ASP.NET Web Form application, you can use the Web Forms classes (System.Web).

    16Jan, 2012
    The .NET Framework

    The .NET Framework

    The Microsoft .NET Framework is an integral part of the Microsoft Windows Operating System components that supports building and running applications and XML Web services that take advantage of this new technology.
    The .NET Framework is designed to fulfill the following objectives:

    • To provide a consistent object-oriented programming environment where: 1) object code is stored and executed locally, 2) executed locally but Internet-distributed; or, 3) executed remotely.
    • To provide a code-execution environment that minimizes software deployment and versioning conflicts.
    • To provide a code-execution environment that promotes safe execution of code, including code created by an unknown or semi-trusted third party.
    • To provide a code-execution environment that eliminates the performance problems of scripted or interpreted environments.
    • To make the developer experience consistent across widely varying types of applications, such as Windows-based applications and Web-based applications.
    • To build all communication on industry standards to ensure that code based on the .NET Framework can integrate with any other code.

    The .NET Framework has two main components:

    1. The common language runtime; and,
    2. The .NET Framework class library.

    The common language runtime

    The common language runtime is the foundation of the .NET Framework. You can think of the runtime as an agent that manages code at execution time, providing core services such as memory management, thread management, and remoting, while also enforcing strict type safety and other forms of code accuracy that promote security and robustness. In fact, the concept of code management is a fundamental principle of the runtime. Code that targets the runtime is known as managed code, while code that does not target the runtime is known as unmanaged code. More about the Common Language Runtime at: http://www.daprose.com/?p=1267

    The .NET Framework class library

    The class library is the other main component of the .NET Framework, it is a comprehensive object-oriented collection of reusable types that you can use to develop applications ranging from traditional command-line or graphical user interface (GUI) applications to applications based on the latest innovations provided by the ASP.NET technology, such as Web Forms and XML Web services.
    The .NET Framework can be accessed by unmanaged components that load the common language runtime into their processes and initiate the execution of managed code, thereby creating a software environment that can exploit both managed and unmanaged features.

    The .NET Framework Runtime Hosts

    The .NET Framework not only provides several runtime hosts, but also supports the development of third-party runtime hosts. For example, ASP.NET hosts the runtime to provide a scalable, server-side environment for managed code. ASP.NET for example, works directly with the runtime to enable ASP.NET applications and XML Web services.
    The Microsoft Internet Explorer is an example of an unmanaged application that hosts the runtime (in the form of a MIME type extension). Using Internet Explorer to host the runtime enables you to embed managed components or Windows Forms controls in HTML documents. Hosting the runtime in this way makes managed mobile code similar to Microsoft ActiveX controls possible, but with significant improvements that only managed code can offer, such as semi-trusted execution and isolated file storage.
     

    15Nov, 2011
    RETURN

    Cause a shell function to exit with the return value n.

    SYNTAX
    return [n]

    Options
    n Return value i.e. an errorlevelIf n is not supplied, the return value is the exit status of the last command executed in the function. This may also be used to terminate execution of a script being executed with the . (or source) builtin, returning either n or the exit status of the last command executed within the script as the exit status of the script.

    The return status is false if return is used outside a function and not during the execution of a script by . or source.

    return is a BOURNE shell command and a POSIX &qt;special&qt;&qt; builtin.

    15Nov, 2011
    READ

    Read a line from standard input

    SYNTAX

    read [-ers] [-a aname] [-p prompt] [-t timeout]
    [-n nchars] [-d delim] [name...]

    OPTIONS

    -a aname
    The words are assigned to sequential indices of the array variable aname,
    starting at 0. All elements are removed from aname before the assignment.
    Other name arguments are ignored.

    -d delim
    The first character of delim is used to terminate the input line,
    rather than newline.

    -e
    If the standard input is coming from a terminal, Readline is used
    to obtain the line.

    -n nchars
    read returns after reading nchars characters rather
    than waiting for a complete line of input.

    -p prompt
    Display prompt, without a trailing newline, before attempting
    to read any input. The prompt is displayed only if input is coming from a
    terminal.

    -r
    If this option is given, backslash does not act as an escape character.
    The backslash is considered to be part of the line. In particular, a backslash-newline
    pair may not be used as a line continuation.

    -s
    Silent mode. If input is coming from a terminal, characters are not echoed.

    -t timeout
    Cause read to time out and return failure if a complete line
    of input is not read within timeout seconds. This option has no
    effect if read is not reading input from the terminal or a pipe.This is a BASH shell builtin.

    One line is read from the standard input, and the first word is assigned to the first name, the second word to the second name, and so on, with leftover words and their intervening separators assigned to the last name.

    If there are fewer words read from the standard input than names, the remaining names are assigned empty values.

    The characters in the value of the IFS variable are used to split the line into words.

    The backslash character &qt;&qt;&qt; may be used to remove any special meaning for the next character read and for line continuation.

    If no names are supplied, the line read is assigned to the variable REPLY. The return code is zero, unless end-of-file is encountered or read times out.

    Examples

    #!/bin/bash
    read var_year
    echo "The year is: $var_year"


    echo -n "Enter your name and press [ENTER]: "
    read var_name
    echo "Your name is: $var_name"

    15Nov, 2011
    RCP

    Remote Copy – move files between machines.
    Each file or directory is either a remote filename of the form rname@rhost:path or a local filename.

    SYNTAX

    rcp [options] file1 file2

    rcp [options] file ... directory

    OPTIONS
    -k Attempt to get tickets for remote host; query krb_realmofhost to determine realm.

    -p Preserve modification times and modes of the source files.

    -r If any of the source files are directories, rcp copies each subtree rooted at that name.
    The destination must be a directory.

    -x Turns on DES encryption for all data passed by rcp.

    15Nov, 2011
    RAM

    ram disk device

    Ram is a block device to access the ram disk in raw mode.
    It is typically created by:

    mknod -m 660 /dev/ram b 1 1
    chown root:disk /dev/ram

    FILES
    /dev/ram

    15Nov, 2011
    QUOTACTL

    Set disk quotas

    SYNTAX
    #include

    int quotactl(cmd, special, uid, addr)
    int cmd;
    char *special;
    int uid;
    caddr_t addr;

    DESCRIPTION
    The quotactl() call manipulates disk quotas. cmd indi­
    cates a command to be applied to UID id or GID id. To set
    the type of quota use the QCMD(cmd,type) macro. special
    is a pointer to a null-terminated string containing the
    path name of the block special device for the file system
    being manipulated. addr is the address of an optional,
    command specific, data structure which is copied in or out
    of the system. The interpretation of addr is given with
    each command below.

    Q_QUOTAON Turn on quotas for a file system. addr
    points to the path name of file containing
    the quotas for the file system. The quota
    file must exist; it is normally created
    with the quotacheck program. This call
    is restricted to the super-user.

    Q_QUOTAOFF Turn off quotas for a file system. addr
    and uid are ignored. This call is
    restricted to the super-user.

    Q_GETQUOTA Get disk quota limits and current usage for
    user or group id. addr is a pointer to a
    dqblk structure (defined in
    ). Only the super-user may
    get the quotas of a user other than him­
    self.

    Q_SETQUOTA Set disk quota limits and current usage for
    user or group id. addr is a pointer to a
    dqblk structure (defined in
    ). This call is restricted
    to the super-user.

    Q_SETQLIM Set disk quota limits for user or group id.
    addr is a pointer to a dqblk structure
    (defined in ). This call is
    restricted to the super-user.

    Q_SYNC Update the on-disk copy of quota usages for
    a file system. If special is null then all
    file systems with active quotas are
    sync&qt;&qt;ed. addr and uid are ignored.

    RETURN VALUES

    0 on success.

    -1 on failure and sets errno to indicate the error.

    15Nov, 2011
    QUOTACHECK

    Scan a file system for disk usage

    SYNTAX

    quotacheck [-g] [-u] [-v] -a
    quotacheck [-g] [-u] [-v] filesys ...

    Quotacheck performs a filesystems scan for usage of files and directories, used by either user or group. The output is the quota file for the corresponding filesystem. By default the names for these files are:

    – A user scan: quota.user
    – A group scan: quota.group

    The resulting file consist of a struct dqblk for each possible id up to the highest existing uid or gid and contains the values for the disk file and block usage and possibly excess time for these values. ( for definitions of struct dqblk see )

    Quotacheck should be run each time the system boots and mounts non-valid file systems. This is most likely to happen after a system crash.

    The speed of the scan is proportional to the number of directories/files.

    OPTIONS
    -v This way the program will give some useful infor­
    mation about what it is doing, plus some fancy
    stuff.

    -d This means debug. It will result in a lot of infor­
    mation which can be used in debugging the program.
    The output is very verbose and the scan will not be
    fast.

    -u This flag tells the program to scan the disk and to
    count the files and directories used by a certain
    uid. This is the default action.

    -g This flag forces the program to count the the files
    and directories used by a certain gid.

    -a Check all of the quotas for the filesystems men­
    tioned in /etc/fstab. Both user and group quotas
    are checked as indictated by the /etc/fstab
    options.

    -R When used in conjunction with -a, all filesystems
    except the root filesystem are checked for quotas.

    NOTE Quotacheck should only be run as Super User. Non-priviliged users are presumably not allowed to read all the directories on the given file system.

    Files
    quota.user, quota.group, /etc/fstab