|
Technology |
Remote Object |
Connection |
User Interface |
Browser Requirements |
|
Remote Scripting |
Script function in an ASP page |
An HTTP request issued by a hidden Java language applet |
Updated via DHTML scripting |
Java and ECMAScript |
|
Remote Data Services |
COM component installed on the Web server |
A special COM object supporting HTTP |
Updated via DHTML scripting |
COM support |
|
Data Binding |
Connection String |
An ActiveX control getting data |
Automatically updated via DHTML |
Internet Explorer 4.0 and later |
|
XmlHttp |
ASP page |
A hidden HTTP request issued by the component itself |
Updated via XSL or DHTML scripting |
Internet Explorer 5.0 |
|
Frames |
ASP page |
An HTTP request issued by the browser |
A brand new page |
Frame support |
Figure 5 RS Remote Call Functions
|
Function |
Description |
|
RSEnableRemoteScripting(url) |
Instantiates the Java language applet driving the HTTP conversation with the Web server |
|
RSExecute(asp, method, params, callback, error_callback, context) |
Lets you issue both synchronous and asynchronous remote calls through the previously instantiated applet |
|
RSGetASPObject(asp) |
Creates and returns a fake object with the same programming interface as the target ASP page |
Figure 6 Remote Scripting Demo
<HTML>
<LINK rel="stylesheet" href="styles.css">
<HEAD>
<TITLE>Employee Info</TITLE>
</HEAD>
<BODY>
<script language="JavaScript" src="http://expoware/_ScriptLibrary/rs.htm">
</script>
<script language="JavaScript">
RSEnableRemoteScripting("http://expoware/_ScriptLibrary");
</script>
<table border=0 cellpadding=0 width=100%>
<td width=20%><img src="mind.gif"></img></td>
<td class="heading" width=75%> Employee Info Finder<br>
<span class=subhead>brought to you by <big>Remote Scripting</big>
and <big>DHTML</big></span></td>
</table>
<br>
Enter the last name of the employee you want to search:
<br><input type=text name="txtEmpName" size=40>
<input type=button name=btnExecute style="width=150"
value="Show"
onclick="execCall()">
<hr>
<br>
<table>
<tr><td><b>Employee</b></td><td><span id="empName"></td></tr>
<tr><td><b>Title</b></td><td><span id="empTitle"></td></tr>
<tr><td><b>City</b></td><td><span id="empCity"></td></tr>
<tr><td><b>Hired on</b></td><td><span id="empHired"></td></tr>
</table>
<hr>
<textarea cols=60 row=5 name="errLog">
</textarea>
<SCRIPT LANGUAGE="javascript">
var serverURL = "http://expoware";
var pageURL = "/mind/rs/server/EmpData.asp";
var aspObject;
function refreshPage(co)
{
if (co.status == 0) {
a = co.return_value;
empName.innerText = a[1];
empTitle.innerText = a[2];
empCity.innerText = a[3];
empHired.innerText = a[4];
}
}
function errHandler(co)
{
if (co.status != 0) {
co.context.value = co.message;
}
}
function execCall()
{
errLog.value = "";
var co = RSExecute(serverURL+pageURL, "GetEmployeeInfo",
txtEmpName.value,
refreshPage, errHandler, errLog);
}
</SCRIPT>
</BODY></HTML>
Figure 7 RSExecute Arguments
|
Parameter |
Description |
|
AspPage |
URL pointing to the ASP page with the JavaScript object to call. |
|
MethodName |
Name of the function to be called. |
|
Params |
Optional. Zero or more arguments to be passed to the method. |
|
Callback |
Optional. Reference to the callback function to be used when calls are asynchronous. |
|
ErrCallback |
Optional. Reference to the callback function to be used in case of error during the execution. |
|
Context |
Optional. Reference to any external argument you want the callback to receive. |
Figure 9 ASP Remote Page
<%@ LANGUAGE=VBSCRIPT %>
<% RSDispatch %>
<SCRIPT RUNAT=SERVER Language=javascript>
<!--#INCLUDE VIRTUAL="/_ScriptLibrary/RS.ASP"-->
function Description()
{
this.GetEmployeeInfo = DoGetEmployeeInfoAsArray;
}
public_description = new Description();
function DoGetEmployeeInfoAsArray(empName)
{
sql = "select * from Employees where [LastName]='" + empName + "'";
rst = new ActiveXObject("ADODB.Recordset");
rst.CursorLocation = 3; // adUseClient
rst.Open(sql, "NW");
i = 0;
aRecs = new Array();
aRecs[i++] = rst.RecordCount + " record(s) found.";
if (rst.RecordCount == 1) {
aRecs[i++] = rst.Fields("EmployeeID").Value + " - " +
rst.Fields("TitleOfCourtesy").Value + " " +
rst.Fields("FirstName").Value + " " +
rst.Fields("LastName").Value;
aRecs[i++] = rst.Fields("Title").Value;
aRecs[i++] = rst.Fields("City").Value + " " +
rst.Fields("Region").Value + ", " +
rst.Fields("Country").Value;
d = new Date(rst.Fields("HireDate").Value);
aRecs[i++] = (1+d.getMonth()) + "/" + d.getDate() + "/" + d.
getYear();
}
return aRecs;
}
</SCRIPT>
Figure 13 From Recordset to Array
<SCRIPT RUNAT=SERVER Language="JavaScript">
// **************************************************************
// * Rs2Array.js
// * Provides a server-side JScript function to convert
// * recordsets to arrays
// **************************************************************
function Recordset2Array(rst)
{
var numOfFields, i, j
var aRS;
// Creates a new array to hold the RS
aRS = new Array();
// Adds a first child array with all the field names
aRS[0] = new Array();
numOfFields = rst.Fields.Count;
for (i=0; i<numOfFields; i++)
aRS[0][i] = rst.Fields.Item(i).Name;
// Adds as many child arrays as needed to hold all the records
i = 1;
while (!rst.EOF) {
aRS[i] = new Array();
for (j=0; j<numOfFields; j++)
aRS[i][j] = String(rst.Fields.Item(j).Value);
// Next record and next item in the array
rst.MoveNext();
i++;
}
return aRS;
}
</SCRIPT>