Category Archives: JavaScript

JavaScript

01.28.13
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Each time a new client accesses the server application


Each time a new client accesses the server application, a new client object is created. However, there are no built-in properties for the client object.
If you need information retained about the client, then you create a property.
01.28.13
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A very common use for a client property is a client identification number


A very common use for a client property is a client identification number. When the client first accesses the server, he can receive a form. The server can then process this information and assign the client an identification number.
This might be randomly generated or looked up from a list of previous customers.As an example, a client can send a request. Part of the request can include a user supplied customer number in the text box named idnumber. You can then create a client property called custNo with the following line: client.custNo = request.idnumber
01.28.13
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LiveWire automatically deletes any client object with no property values


LiveWire automatically deletes any client object with no property values.So if you don’t use a client object, you don’t have to worry about deleting it. In other words, you only have to clean up after yourself.
The default expiration is ten minutes of inactivity. If the client does not send another request to the server within ten minutes of the previous request, the object expires.
01.28.13
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Cookies is the technique for retaining clint information


Cookies is the technique for retaining clint information. The browser must support the Netscape cookie protocol. If supported, the server sends the information to the client as name/value pairs. Obviously, this increases network traffic, but can offer substantial advantages to large access servers.
There are several other techniques for maintaining this information. However, they all have limited application. Client URL encoding causes a large increase in network traffic. Using IP addresses on the server only works for clients using fixed IP addresses. This might work for some intranet applications; for general use, it is worthless. For more details, refer to the LiveWire documentation.
01.28.13
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The project object has no pre-defined properties


The project object has no pre-defined properties. If you need to hold information for your project, you create the objects you need in the application.

Many projects need to store values. For example, in billing a customer you might need the next invoice number. This number is incremented when another invoice is generated.
01.28.13
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In any multi-user environment you must deal with cases of simultaneous access


In any multi-user environment you must deal with cases of simultaneous access. On file servers, you lock a file while you are using it. You unlock it when you are finished with the operation. The other user must wait for you to finish.
If you do not lock files, the data can be corrupted. A simple example is with two people editing a document. If both are editing at the same time, then one saves his changes before the other. The problem is that the first set of changes are over written by the second.

01.28.13
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As with most JavaScript objects, you can add properties to server objects


As with most JavaScript objects, you can add properties to server objects. For example, you might want to add the time the server was last accessed. This might be read by a monitoring routine, as follows:
today = new Date()
server.accesstime = today.getTime()
As with project objects, server objects should be locked. Since you can have more than one process accessing the object at one time, you should use the same locking procedure as discussed for project objects.
01.28.13
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Undoubtedly with your active interest in building Web sites


Undoubtedly with your active interest in building Web sites, you have dealt with Common Gateway Interface (CGI) scripts. Prior to JavaScript, this was the primary means of creating interactive applications. Libraries of CGI scripts include counters, e-mailers, message boards, and many other functions
LiveWire can replace CGI programming. Instead of calling external programs, the server software runs applications that are closely integrated to it. JavaScript is the language of these applications.
01.28.13
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Like any other Website a browser requests a Web page to access a livewire application


Like any other Web site, a browser requests a Web page to access a LiveWire application. The browser can request any of the pages within an application. The server sees the request like any other request, though it is handled differently.
In turn, the browser is not concerned if the HTML is a static page or from a dynamic LiveWire application. The form of the URL is as follows:

http://server.domain/application/page.html

01.28.13
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The SERVER tag contains JavaScript that either executes


The SERVER tag contains JavaScript that either executes a statement or produces HTML with the write function. A JavaScript statement can be a rather simple routine or a more complex set of functions.
Using the SERVER tag with JavaScript to produce HTML is very common. As a very simple example, you might create a document that returns the IP address to the browser, as follows:

<P>Your request came from ip address:
<SERVER> write(request.ip) </SERVER>