TACL Command

The use of commands is the simplest interactive use of TACL.
Predefined commands of TACL such as:

RUN                    Runs a process

STATUS              Displays information about one or more running processes

ENV and WHO    Describes your TACL environment

FUP                    To start a process, and type the program name, to invoke the program. 

User can include user-defined commands if you or your system manager define them. 

TACL Metacharacters

Square Brackets ([ ])
You can enclose var1 in square brackets to obtain the contents of var1 or you can omit the brackets to obtain the text var1:

12> #OUTPUT [var1]
3
13> #OUTPUT var1
var1

** However, when you supply a variable name as an argument to one of these commands or built-in functions (#IF #COMPUTE), you do not need to enclose a variable name in square brackets.

Tilde (~)
The tilde is used in combination with another character:

 ~; simulates an end-of-line character。
 ~_ represents a space character when #OUTFORMAT is set to PRETTY.
 TACL replaces the combination of a tilde and a metacharacter with the metacharacter itself. For example, ~[ becomes [, and ~== becomes ==.
 TACL replaces the combination of a tilde and a character that is not a metacharacter with a single question mark. For example, ~A becomes ?

Question Mark (?)
TACL uses the question mark character for two purposes:

- Displaying previous command lines
- Specifying the start of a TACL directive

To start a line with a question mark for any other purpose, use two question marks. TACL then discards the first question mark and any adjacent spaces and treats the remainder of the line as text.

TACL Programming

Tandem Advanced Command Language (TACL) is a software application that provides an interface to the HP NonStop operating system. You can use TACL either as an interactive command interface or as an interpreted programming language to construct programs. NonStop servers are key components of the backbone infrastructure of the largest banks, casinos, retailers, telephone companies, email systems, and stock exchanges worldwide.

As a programming language, the TACL product is most often used for managing systems and processes. You can, for example, use TACL to:

- Automate system startup and shutdown procedures.

- Automate subsystem startup and shutdown procedures; 

- Run utilities and issue commands−either with a fixed set of commands or a flexible set;

- Create a customized environment that simplifies commonly performed tasks for users.

- Control subsystem operation using the Subsystem Programmatic Interface (SPI).

- Communicate with the Event Management Service (EMS) and generate EMS messages.

General Syntax Notation: 

Uppercase letters indicate keywords and reserved words: STATUS

Lowercase italic letters indicate variable items: file-name

[#IF [timenow] > 12 |THEN|
 #OUTPUT Good afternoon
|ELSE|
 #OUTPUT Good morning
]


[#CASE [errornumber]
 |0|
 #OUTPUT [filename] was purged
 |OTHERWISE|
 #OUTPUT [filename] could not be purged
 #OUTPUT Error [errornumber]
]

Web-based System Development: Tutorial 1

What is the Internet?
Internet is a global data communication system, which provides connectivity between computers.

What is the difference between the web & the Internet?
The Web is one of the services communicated via the Internet. It is a collection of interconnected documents and other resources, linked by hyperlinks and URLs.

Briefly explain how does the Web work?
The web information is stored in the Web Pages. Then web pages are stored in the computers called Web Servers. After that computer access the pages is called Web Clients using a specific Web Browser.

Server generalized to describe a host that is deployed to execute one or more such programs.

Web development is a broad term for the work involved in developing a web site for the Internet (World Wide Web) or an intranet (a private network).

The World Wide Web (WWW) is a system of interlinked hypertext documents accessed via the Internet.

HTTP used to deliver text, image, & sound files on the Web.

HTML provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items.

Who manages the Internet?

There is no such a central authority that manages the whole Internet.

The Internet is managed in a hierarchical fashion with several organizations on the top.

Internet Assigned Numbers Authority (IANA)

Regional Internet Registry for Europe (RIPE)

Asian Pacific Network Information Center (APNIC)

American Registry for Internet Numbers (ARIN)

Who defines the Web standards?

The Web standards are not defined or setup by the browser companies or Microsoft, but the World Wide Web Consortium (W3C).