Software Lab Assignments

Aim – To study about the Zope as a open source web application server.

Theory – Zope is an open source web application server primarily written in the python programming language. It features a transactional object database which can store not only content and custom data but also dynamic HTML templates, scripts, a search engine, and relational database (RDBMS) connections and code. It features a strong through-the-web development model. Built around the concept of “safe delegation of control”, Zope’s security architecture also allows you to turn control over parts of a web site to other organizations or individuals. The transactional model applies not only to Zope’s object database, but to many relational database connectors as well, allowing for strong data integrity. This transaction model happens automatically, ensuring that all data is successfully stored in connected data sources by the time a response is returned to a web browser or other client.

Unlike common file-based Web templating systems such as ASP or PHP, Zope is a highly object-oriented Web development platform that covers much more of the problem domain for Web application developers. It provides clean separation of data, logic and presentation, an extensible set of built-in objects and a powerful integrated security model. The Zope infrastructure relieves the developer of most of the onerous details of Web application development such as data persistence, data integrity and access control, allowing you to focus on the problem at hand.

Zope users include Viacom, Boston.com, SGI, AARP, Bell Atlantic Mobile, Red Hat, NASA, The US navy, Digital Garage and Storm Linux.

                            Zope provides all of the necessary tools to integrate data and content from nearly any source into powerful, coherent and maintainable Web applications:

   

·                     Through-the-Web management

   

·                     Integrated access control

   

·                     Content management

   

·                     Enterprise data access

   

·                     Built-in search tools

   

·                     Powerful data sharing

    

·                     Safe delegation

1.  The Web Application Platform

2.  XML Support

3.  Data Access

4.  Data Sharing

5.  Integrated searching

                                 A new version of Zope, Zope 3, has been in development for some years. Zope 2 has proven itself as a useful framework for web applications development, but its use revealed some shortcomings. To name a few, creating Zope 2 products involves copying a lot of boilerplate code – “magic” code – that just has to be there, and the built-in management interface is difficult to modify or replace. Zope 3 is a rewrite of the software that attempts to address these shortcomings while retaining the advantages of Zope that led to its popularity. Zope 3 is based on a component architecture that makes it easy to mix software components of various origins written in Python. The first production release of the new software, Zope X3 3.0.0, was released on November 6, 2004. The current production release, Zope 3.3.0, was released on September 27, 2006. We can download it from internet.

                   So we have studied about the Zope, its features, its application and how it is useful to help us in computer field and how to get it.

Aim:           Study of Python (programming language)

Python is an object-oriented high-level programming language, first released by Guido van Rossum in 1991. Python has a fully dynamic type system and uses automatic memory management; it is thus similar to Perl, Ruby, Scheme, Smalltalk, and Tcl.

The philosophy behind Python is noteworthy among high-level programming languages because it emphasizes the importance of programmer effort over computer effort, and because it rejects more arcane language features, prioritizing readability over speed or expressiveness. Python is often characterized as minimalist, although this only applies to the core language’s syntax and semantics; the standard library provides the language with a large number of additional libraries and extensions.

Python was designed to be a highly readable language. It aims toward an uncluttered visual layout, uses English keywords frequently where other languages use punctuation, and has notably fewer syntactic constructions than many structured languages such as C, Perl, or Pascal. Python uses indentation, rather than curly braces, to delimit statement blocks. An increase in indentation comes after certain statements; a decrease in indentation signifies the end of the current block. Python’s statements include:

    * The if statement, which conditionally executes a block of code, along with else and elif (a contraction of else-if).

  

 * The while statement, which runs a block of code until a condition is False.

  

 * The for statement, which iterates over an iterable, capturing each element to a local variable for use by the attached block.

  

 * The class statement, which executes a block of code and attaches its local namespace to a class, for use in object oriented programming.

   

* The def statement, which defines a function.

Each statement has its own semantics:

for e.g.  the def statement does not execute its block immediately, unlike most other statements.

CPython does not support continuations, and according to Guido van Rossum, never will. However, better support for co routine-like functionality is provided in 2.5, by extending Python’s generators. Prior to 2.5, generators were lazy iterators — information was passed monodirectionally out of the generator.

 

The mainstream Python implementation, also known as CPython, is written in C, and is distributed with a large standard library written in a mixture of C and Python. CPython ships for a large number of supported platforms, including most modern Unices and Microsoft Windows; see the full list for more. The code base is written in compliant C89, and is easily portable to most operating systems, especially POSIX-compliant or Unix-like operating systems.

Python was originally developed as a scripting language for the Amoeba distributed operating system which was capable of making system calls; however, that version is no longer maintained. CPython was intended from almost its very conception to be cross-platform; its use and development on esoteric platforms such as Amoeba alongside more conventional ones like Unix or Macintosh has greatly helped in this regard.

Stack less Python is a significant fork of CPython that implements micro threads. It can be expected to run on approximately the same platforms that CPython runs on.

There are two other major implementations: Jython for the Java platform and Iron Python for the .NET platform. PyPy is an experimental self-hosting implementation of Python, in Python, that can output a variety of types of byte code and object code. Several other experimental implementations have been created, but have not yet been widely adopted.

Several programs exist to package Python programs into standalone executables, including py2exe and py2app.

Many Python programs can run on different Python implementations, on such disparate operating systems and execution environments, without change. In the case of the implementations running on top of the Java virtual machine or the Common Language Runtime, the platform-independence of these systems is harnessed by their respective Python implementation.

Many third-party libraries for Python (and even some first-party ones) are only available on Windows, Linux, BSD, and Mac OS X

 Thus we have studied Python (programming language) successfully

                     To study Samba as an open source project for sharing

                     Samba on Linux is something completely different. Samba is an implementation of a Server Message Block (SMB) protocol server that can be run on almost every variant of UNIX in existence. Samba is an open source project, just like Linux. The entire code is written in C so it is easily portable to all flavors of UNIX. Samba is a tool for the peaceful coexistence of UNIX and Windows on the same network on the level of File and Print sharing over the NetBIOS protocol. It allows UNIX systems to move into a Windows “Network Neighborhood” without causing a mess. With Samba, UNIX servers are acting as any other Windows server, offering its resources to the SMB clients.

                       When the Samba package is installed, a default configuration file is installed in: etc/smb.conf

                       A simple share can be defined in the smb.conf file as follows:

[redbook]

comment = Redbook files

path = /redbook

browseable = yes

printable = no

writable = yes

write list = @users

                         Although we can control the share permissions with share parameters, UNIX permissions are applied before share permissions. Make sure the UNIX permissions let the users access the share directory in the UNIX environment. When a user creates a new file on the shared directory, the default create mask used is 0744. For directory creation, the default create mask is 0755.

                          For handling home directories smb.conf has a special share section called [homes]. This share definition is used for all home directories, so we don’t need to create separate shares for each user. When a client requests a connection to a share, existing shares are scanned. If a match is found, that share is used. If no match is found, the requested share is treated as the username and validated by security. If the name exists and the

password is correct, a share with that name is created by cloning the [homes]

section. Home share definitions use the same parameters as normal shares. The

following is an example of a [homes] share definition in the smb.conf file:

[homes]

comment = Home Directories

path = %H

valid users = %S

browseable = no

writable = yes

create mode = 0700

directory mode = 0700

%H This variable represents the home directory of the user.

%S The name of the current service, which is in the case of [home]

shares equal to username.

                              A Samba server uses the same procedure for [printer] shares as for [home] shares. The share definitions and user names are tested against the requested share name. If a match is found in the [printers] share section, a share with that name is cloned with the name of the requested service. The following is an example of a [printers] definition in the smb.conf file:

[printers]

comment = All Printers

path = /var/spool/samba

browseable = no

# Set public = yes to allow user ’guest account’ to print

guest ok = no

writable = no

printable = yes

create mask = 0700

.

    One can start the Samba server by executing the following

command:

/etc/rc.d/init.d/smb start

You will see:

Starting SMB services:

Starting NMB services:

Two daemons are started: smbd and nmbd. smbd is the Samba server and nmbd is the WINS server. The Samba server can be stopped by executing the command:

/etc/rc.d/init.d/smb stop

Whenever you modify the smb.conf configuration file you must restart the Samba server.

1. Create the directory that will be used for the share. You can do this by

executing the command:

mkdir /home/public

2. Make sure that UNIX permissions are set correctly in the directory so that only

intended users have access rights to it.

To restart the Samba server, click the Status icon. Click Restart smbd. On this page you can also restart the WINS server by clicking Restart nmbd.

                        Thus we have studied Samba, an implementation of a server message block protocol.

Aim: Create a Help file for an Application using Help Workshop

Theory: Help files can be created in HTML Help Workshop or in any other HTML authoring tool (for example, Front Page, Word, or a text editor). Then use the Answer Wizard Builder to create the AW file from the HTML or CHM Help content.

Creating custom Help topics involves these steps:

           

Ø Choosing a custom Help file format (HTML or CHM files).

Ø Creating the custom HTML topics.

If you want to create, format, and link HTML Help topics, you can use any HTML editor. If you want to create CHM files, install Microsoft HTML Help Workshop and compile your custom Help.

 The format you choose for your Help files also depends on where you plan to store the files and how often you need to update the content.

Ø  HTML Help files can be stored on either a Web server or a network file share. If they         are stored on either of these, the following advantages apply:

Ø  You can update Help content in one place and not have to worry about deploying or updating it on individual computers.

Ø  No hard-disk space is required on a user’s computer.

Ø  HTML Help does not require a hosted Web site to display Help content.

           

Ø  If you use HTML Help files hosted on a Web site, users must have access to the Web.

Ø  A CHM file is a compressed HTML Help Meta file. You can take the equivalent of an entire Web site and compile it into a CHM. It uses a special technology to combine HTML files into one file with a special directory, index, and file structure similar to a compressed drive.

Ø  CHM files can be compressed, taking up less hard-disk space and providing more portability than an entire Web site.

Ø  Users get faster results when the CHM file is stored locally.            

Ø  A single CHM file can contain an entire Web site of HTML files.

Ø  Users do not need access to the Web or the network.

           

Ø  You are required to register the CHM before it can be used.

Ø  However, once it is registered, it does not need to be registered again.

Ø  You are required to recompile the file every time a change is made to the Help system.

After you choose what format you will use for your custom Help topics, you can begin creating your topics. Where you start the process of creating custom Help depends on what format your Help files are in. If you have CHM files or Help topics in Win Help format, you can import them into HTML Help Workshop.

Start with Win Help sources

Microsoft HTML Help Workshop can automatically convert the source files for these to HTML.

After converting your source files, use HTML Help Workshop to create a CHM file from the new HTML files.

Help files can be created in HTML Help Workshop or in any other HTML authoring tool (for example, Front Page, Word, or a text editor). Then use the Answer Wizard Builder to create the AW file from the HTML or CHM Help content.

Conclusion: Thus we have created a help file using HELP WORKSHOP

AIM:             

 To study Berkeley Internet Name Domain (BIND) in LINUX

THEORY:                             

           BIND (Berkeley Internet Name Domain, previously: Berkeley Internet Name Daemon) is the most commonly used DNS server on the Internet, especially on UNIX systems, where it is a de facto standard. Supported by Internet Systems Consortium. BIND was originally created by four graduate students with CSRG at the University of California, Berkeley and first released with 4.3BSD. Paul Vixie started maintaining it in 1988 while working for DEC.

             A new version of BIND (BIND 9) was written from scratch in part to address the architectural difficulties with auditing the earlier BIND code bases, and also to support DNSSEC (DNS Security Extensions). Other important features of BIND 9 include: TSIG, DNS notify, nsupdate, IPv6, rndc flush, views, multiprocessor support, and improved portability architecture. It is commonly used on Linux systems.

History:                          

             BIND was originally written in the early 1980s under a DARPA grant. In the mid-1980s, DEC employees took over BIND development. One of these employees was Paul Vixie, who continued to work on BIND after leaving DEC. He eventually helped start the ISC, which became the entity responsible for maintaining BIND.

The development of BIND 9 was done with a combination of commercial and military contracts. Most of the features of BIND 9 were funded by UNIX vendors who wanted to ensure that BIND stayed competitive with Microsoft’s DNS offerings; the DNSSEC features were funded by the US military who felt that DNS security was important.

Criticisms:                        

     Like Sendmail, WU-FTPD, and other systems dating back to the earlier laissez-faire days of the Internet, BIND 4 and BIND 8 have had a large number of serious security vulnerabilities over the years. BIND 9, being a rewrite, has a much better security history.

GeoDNS:                        

        GeoDNS is a 40-line patch to BIND to allow split horizon DNS, such that different requesters receive different responses, depending on proximity.

In this way if a website has, for example, a French server, a US server and a South Korean server, they can easily specify that people in Europe go to the French server, people in East Asia go to the Korean server and those in the rest of the world be served by the American server. This can give improved performance and potentially lower costs than a single hosting location or a round robin DNS setup.

As it is DNS based, it is much easier to deploy than BGP any cast. It does not require any support from the ISP and will not break existing connections when the server selected for a particular client changes. However, as it is not intimately tied into the network infrastructure it is likely to be less accurate at sending data to the nearest server.

CONCLUSION:                    

  Thus we have successfully studied the application of BIND in Linux.

AIM: Creating SDI, MDI, Dialog Based Application

THEORY: 

Dialog Box :  A  dialog box is a specialized window that is used to provide feedback or collect input from the user. Dialog boxes come in all shapes and sizes, ranging from simple message boxes that display single lines of text to large dialog boxes that contain sophisticated controls. Dialog boxes are also used for one-way communication with a user, such as “splash screens” used to display copyright and startup information as a program is launched. Dialog boxes are sometimes used to notify the user about the progress of a lengthy operation.

SDI: Single Document Interface or SDI is a method of organizing graphical user interface applications into individual windows that the operating system’s window manager handles separately. A window does not have a “background” or “parent” window containing its menu or toolbar; instead, each window contains its own menu or toolbar. Applications which allow the editing of more than one document at a time.

MDI: Multiple Document Interface (MDI) are those whose windows reside under a single parent window as opposed to all windows being separate from each other.

Advantages

• Many child windows do not fill up the OS task management interface, as they are hierarchically organized. Users simply switch applications.

• With MDI a single menu bar and/or toolbar is shared between all child windows, reducing clutter and increasing efficient use of screen space.

• All child windows for an application can be hidden/shown/minimized/maximized as a whole.

Disadvantages

• Cannot be used successfully on desktops using multiple monitors.

• MDI can make it more difficult to work with several applications at once, by restricting the ways in which windows from multiple applications can be arranged together.

• The shared menu changes, which may cause confusion to some users.

The AppWizard In Visual C++, provides the facility of creating MDI or SDI applications. To create a simple SDI program, select Single Document on the opening MFC AppWizard screen. AppWizard displays six Wizard pages filled with default information for a typical SDI program. You can tell AppWizard to create the project for you by pressing the button labeled Finish. AppWizard will create several classes and files for you and create a project that you can use to manage the process of compiling the program AppWizard creates these classes for a program named Hello:

• CHelloApp: Derived from CWinApp, the application class for the program

• CHelloDoc: The program’s document class, derived from CDocument

• CHelloView: The program’s view class derived from CView

• CMainFrame: The main frame class for the program

In addition, AppWizard creates several files that are not used for C++ classes. Some of these files are

• hello.aps: A file that contains a precompiled version of the program’s resources

• hello.clw: A file that contains information used by ClassWizard

• hello.rc: A resource file that contains information about dialog boxes, menus, and other resources used by the program

• resource.h: A header file containing declarations needed for the resources used by the program

• hello.dsp and hello.dsw: The project and workspace files used by Developer Studio to build the program

• stdafx.cpp: A file included in all AppWizard programs that includes all the standard include files

• stdafx.h: A standard header file included in all AppWizard programs that is used to include other files that are included in the precompiled headers

You can use AppWizard to create an MDI application almost as easily as an SDI.