Q1 - What is AJAX?
A - Ajax stands for Asynchronous Javascript & XML. It is a web technology through which a postback from a client (browser) to the server goes partially, which means that instead of a complete postback, a partial postback is triggered by the Javascript XmlHttpRequest object. In such a scenario, web-application users won't be able to view the complete postback progress bar shown by the browser. In an AJAX environment, it is Javascript that starts the communication with the web server.
Ajax technology in a website may be implemented by using plain Javascript and XML. Code in such a scenario may tend to look little complex, for which the AJAX Framework in .NET can be embedded in ASP.NET web applications.
In addition to XML & Javascript, AJAX is also based on DOM - the Document Object Model technology of browsers through which objects of the browser can be accessed through the memory heap using their address.
JSON - Javascript Object Notation is also one of the formats used in AJAX, besides XML.
So basically, in an AJAX-based web application, the complete page does not need to reload, and only the objects in context of ajaxification are reloaded.
Ajax technology avoids the browser flickering.
Ajax technology in a website may be implemented by using plain Javascript and XML. Code in such a scenario may tend to look little complex, for which the AJAX Framework in .NET can be embedded in ASP.NET web applications.
In addition to XML & Javascript, AJAX is also based on DOM - the Document Object Model technology of browsers through which objects of the browser can be accessed through the memory heap using their address.
JSON - Javascript Object Notation is also one of the formats used in AJAX, besides XML.
So basically, in an AJAX-based web application, the complete page does not need to reload, and only the objects in context of ajaxification are reloaded.
Ajax technology avoids the browser flickering.
Q2 - Can Ajax be implemented in browsers that do not support the XmlHttpRequest object?
A - Yes. This is possible using remote scripts.
Q3 - Can AJAX technology work on web servers other than IIS?
A - Yes, AJAX is a technology independent of web server the web application is hosted on. Ajax is a client (browser) technology.
Q4 - Which browsers support the XmlHttpRequest object?
A - Internet Explorer 5.0+, Safari 1.2, Mozilla 1.0/Firefox, Opera 8.0 +, Netscape 7
Q5 - How to we create an XmlHttpRequest object for Internet Explorer? How is this different for other browsers?
A - For Internet Explorer, an ActiveXObject is used for declaring an XmlHttpRequest object in Javascript.
//Code as below for IE:
xmlHttpObject = new ActiveXObject("Msxml2.XMLHTTP");
//For Other browsers, code as below:
xmlHttpObject = new XMLHttpRequest();
xmlHttpObject = new ActiveXObject("Msxml2.XMLHTTP");
//For Other browsers, code as below:
xmlHttpObject = new XMLHttpRequest();
Note that XmlHttpObject used above is simply a variable that holds the XmlHttpRequest object for the respective browsers.
Q6 - What are the properties of the XmlHttpRequest object? What are the different types of readyStates in Ajax?
A - i) onreadyStateChange - This function is used to process the reply from the web server.
ii) readyState - This property holds the response status of the web server. There are 5 states:
0 - request not yet initialized
1 - request now set
2 - request sent
3 - request processing
4 - request completes
iii) responseText - Has the data sent back by the web server
Code snippet below shows an example how these there properties are used to implement ajax :
ii) readyState - This property holds the response status of the web server. There are 5 states:
0 - request not yet initialized
1 - request now set
2 - request sent
3 - request processing
4 - request completes
iii) responseText - Has the data sent back by the web server
Code snippet below shows an example how these there properties are used to implement ajax :
xmlHttpObject.onreadystatechange=function()
{
if(xmlHttpObject.readyState==4)
{
document.Form1.time.value=xmlHttpObject.responseText;
}
}
{
if(xmlHttpObject.readyState==4)
{
document.Form1.time.value=xmlHttpObject.responseText;
}
}
Q7 - What is the ASP.NET Ajax Framework? What versions have been released so far?
A - ASP.NET AJAX is a free framework to implement Ajax in asp.net web applications, for quickly creating efficient and interactive Web applications that work across all popular browsers.
The Ajax Framework is powered with
1 - Reusable Ajax Controls
2 - Support for all modern browsers
3 - Access remote services and data from the browser without tons of complicated script.
Versions of Ajax release
1 - ASP.NET Ajax Framework 1.0 (earlier release to this was called the Atlas)
2 - ASP.NET Ajax Framework 1.0 was available as a separate download for ASP.NET 2.0
The Ajax Framework is powered with
1 - Reusable Ajax Controls
2 - Support for all modern browsers
3 - Access remote services and data from the browser without tons of complicated script.
Versions of Ajax release
1 - ASP.NET Ajax Framework 1.0 (earlier release to this was called the Atlas)
2 - ASP.NET Ajax Framework 1.0 was available as a separate download for ASP.NET 2.0
Q8 - What are Ajax Extensions?
A - The ASP.NET Ajax Extensions are set of Ajax-based controls that work in ASP.NET 2 (or above) based applications.
Ofcourse,they also need the Ajax runtime which is actually the Ajax Framework 1.0.
ASP.NET Ajax Extensions 1.0 have to be downloaded to run with ASP.NET 2.0
The new ASP.NET 3.5 Framework comes with the Ajax Library 3.5 (containing the Ajax Extensions 3.5). So in order to use the latest Ajax, simply download .NET 3.5 Framework.
Summary :
ASP.NET Ajax Extensions 1.0 -> For ASP.NET 2.0
ASP.NET Ajax Extensions 3.5 -> For ASP.NET 3.5
Ofcourse,they also need the Ajax runtime which is actually the Ajax Framework 1.0.
ASP.NET Ajax Extensions 1.0 have to be downloaded to run with ASP.NET 2.0
The new ASP.NET 3.5 Framework comes with the Ajax Library 3.5 (containing the Ajax Extensions 3.5). So in order to use the latest Ajax, simply download .NET 3.5 Framework.
Summary :
ASP.NET Ajax Extensions 1.0 -> For ASP.NET 2.0
ASP.NET Ajax Extensions 3.5 -> For ASP.NET 3.5
Q9 - What is the ASP.NET Control Toolkit?
A - Besides the Ajax Framework (which is the Ajax engine) and Ajax Extensions (which contain the default Ajax controls), there is a toolkit called the Ajax Control Toolkit available for use & download (for free). This is a collection of rich featured, highly interactive controls, created as a joint venture between Microsoft & the Developer Community.
Q10 - What is Dojo?
A - Dojo is a third-party javascript toolkit for creating rich featured applications. Dojo is an Open Source DHTML toolkit written in JavaScript. It builds on several contributed code bases (nWidgets, Burstlib, f(m)), which is why we refer to it sometimes as a "unified" toolkit. Dojo aims to solve some long-standing historical problems with DHTML which prevented mass adoption of dynamic web application development.
Q11 - How to handle multiple or concurrent requests in Ajax?
A - For concurrent requests, declare separate XmlHttpRequest objects for each request. For example, for request to get data from an SQL table1, use something like this...
xmlHttpObject1.Onreadystatechange = functionfromTable1();
and to get data from another table (say table2) at the same time, use
xmlHttpObject2.Onreadystatechange = functionfromTable2();
Ofcourse, the XmlHttpObject needs to be opened & parameters passed too, like as shown below...
xmlHTTPObject1.open("GET","http://"localhost// " + "Website1/Default1.aspx" true);
Note that the last parameter "true" used above means that processing shall carry on without waiting for any response from the web server. If it is false, the function shall wait for a response.
Q12 - How to create an AJAX website using Visual Studio?
A - Using Visual Studio Web Developer Express 2005 & versions above it, Ajax based applications may easily be created. Note that the Ajax Framework & Ajax Extensions should be installed (In case of VS 2005). If using Visual Studio 2008 Web Developer Express or above, Ajax comes along with it (so no need of a separate installation).
Steps: Start Visual Studio, Click on File -> New Website -> Under Visual Studio Installed templates -> Select ASP.NET Ajax-Enabled Site. Enter a location & select OK.
Steps: Start Visual Studio, Click on File -> New Website -> Under Visual Studio Installed templates -> Select ASP.NET Ajax-Enabled Site. Enter a location & select OK.
Q13 - What is the role of ScriptManager in Ajax?
A - ScriptManager class is the heart of ASP.NET Ajax. Before elaborating more on ScriptManager, note that ScriptManager is class and a control (both) in Ajax.
The ScriptManager class in ASP.NET manages Ajax Script Libraries, partial page rendering functionality and client proxy class generation for web applications and services. By saying client proxy class, this means an instance of the Ajax runtime is created on the browser.
This class is defined in the System.Web.Extensions.dll. You will find this DLL in your system's Global Assembly Cache at C:\Windows\Assembly (For XP)
The ScriptManager control (that we may drag on a web form) is actually an instance of the ScriptManager class that we put on a web page. The ScriptManager manages all the ASP.NET Ajax controls on a web page. Following tasks are taken care by the ScriptManager class:
1 - Managing all resources (all objects/controls) on a web page
2 - Managing partial page updates
3 - Download Ajax Script Library to the client (means to the browser). This needs to happen so that Ajax engine is accessible to the browsers javascript code.
4 - Interacting with UpdatePanel Control, UpdateProgress Control.
5 - Register script (using RegisterClientScriptBlock)
6 - Information whether Release OR Debug script is sent to the browser
7 - Providing access to Web service methods from the script by registering Web services with the ScriptManager control
8 - Providing access to ASP.NET authentication, role, and profile application services from client script after registering these services with the ScriptManager control
9 - Enable culture specific display of clientside script.
10 - Register server controls that implement IExtenderControl and IScriptControl interfaces.
ScriptManager class' EnablePartialRendering property is true by default.
The ScriptManager class in ASP.NET manages Ajax Script Libraries, partial page rendering functionality and client proxy class generation for web applications and services. By saying client proxy class, this means an instance of the Ajax runtime is created on the browser.
This class is defined in the System.Web.Extensions.dll. You will find this DLL in your system's Global Assembly Cache at C:\Windows\Assembly (For XP)
The ScriptManager control (that we may drag on a web form) is actually an instance of the ScriptManager class that we put on a web page. The ScriptManager manages all the ASP.NET Ajax controls on a web page. Following tasks are taken care by the ScriptManager class:
1 - Managing all resources (all objects/controls) on a web page
2 - Managing partial page updates
3 - Download Ajax Script Library to the client (means to the browser). This needs to happen so that Ajax engine is accessible to the browsers javascript code.
4 - Interacting with UpdatePanel Control, UpdateProgress Control.
5 - Register script (using RegisterClientScriptBlock)
6 - Information whether Release OR Debug script is sent to the browser
7 - Providing access to Web service methods from the script by registering Web services with the ScriptManager control
8 - Providing access to ASP.NET authentication, role, and profile application services from client script after registering these services with the ScriptManager control
9 - Enable culture specific display of clientside script.
10 - Register server controls that implement IExtenderControl and IScriptControl interfaces.
ScriptManager class' EnablePartialRendering property is true by default.
Q14 - Can we override the EnablePartialRendering property of the ScriptManager class?
A - Yes. But this has to be done before the init event of the page (or during runtime after the page has already loaded). Otherwise an InvalidOperationException will be thrown.
Q15 - How to use multiple ScriptManager controls in a web page?
A - No. It is not possible to use multiple ScriptManager control in a web page. In fact, any such requirement never comes in because a single ScriptManager control is enough to handle the objects of a web page.
Q16 - Whats the difference between RegisterClientScriptBlock, RegisterClientScriptInclude and RegisterClientScriptResource?
A - For all three, a script element is rendered after the opening form tag. Following are the differences:
1 - RegisterClientScriptBlock - The script is specified as a string parameter.
2 - RegisterClientScriptInclude - The script content is specified by setting the src attribute to a URL that points to a script file.
3 - RegisterClientScriptResource - The script content is specified with a resource name in an assembly. The src attribute is automatically populated with a URL by a call to an HTTP handler that retrieves the named script from the assembly.
1 - RegisterClientScriptBlock - The script is specified as a string parameter.
2 - RegisterClientScriptInclude - The script content is specified by setting the src attribute to a URL that points to a script file.
3 - RegisterClientScriptResource - The script content is specified with a resource name in an assembly. The src attribute is automatically populated with a URL by a call to an HTTP handler that retrieves the named script from the assembly.
Q17 - What are type/key pairs in client script registration? Can there be 2 scripts with the same type/key pair name?
A - When a script is registered by the ScriptManager class, a type/key pair is created to uniquely identify the script.
For identification purposes, the type/key pair name is always unique for dentifying a script. Hence, there may be no duplication in type/key pair names.
For identification purposes, the type/key pair name is always unique for dentifying a script. Hence, there may be no duplication in type/key pair names.
Q18 - What is an UpdatePanel Control?
A - An UpdatePanel control is a holder for server side controls that need to be partial postbacked in an ajax cycle. All controls residing inside the UpdatePanel will be partial postbacked. Below is a small example of using an UpdatePanel.
<script runat="server">
protected void btn1_Click(object sender, EventArgs e)
{
lb123.Text = "new";
}
</script>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button id="btn1" runat="server" text="click"/>
<br/>
<asp:Label id="lb123" runat="server" text="Old"/>
</ContentTemplate>
</UpdatePanel>
protected void btn1_Click(object sender, EventArgs e)
{
lb123.Text = "new";
}
</script>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button id="btn1" runat="server" text="click"/>
<br/>
<asp:Label id="lb123" runat="server" text="Old"/>
</ContentTemplate>
</UpdatePanel>
As you see here after running the snippet above, there wont be a full postback exhibited by the web page. Upon clicking the button, the postback shall be partial. This means that contents outside the UpdatePanel wont be posted back to the web server. Only the contents within the UpdatePanel are refreshed.
Q19 - What are the modes of updation in an UpdatePanel? What are Triggers of an UpdatePanel?
A - An UpdatePanel has a property called UpdateMode. There are two possible values for this property: 1) Always 2) Conditional
If the UpdateMode property is set to "Always", the UpdatePanel control’s content is updated on each postback that starts from anywhere on the webpage. This also includes asynchronous postbacks from controls that are inside other UpdatePanel controls, and postbacks from controls which are not inside UpdatePanel controls.
If the UpdateMode property is set to Conditional, the UpdatePanel control’s content is updated when one of the following is true:
1 - When the postback is caused by a trigger for that UpdatePanel control.
2 - When you explicitly call the UpdatePanel control's Update() method.
3 - When the UpdatePanel control is nested inside another UpdatePanel control and the parent panel is updated.
When the ChildrenAsTriggers property is set to true and any child control of the UpdatePanel control causes a postback. Child controls of nested UpdatePanel controls do not cause an update to the outer UpdatePanel control unless they are explicitly defined as triggers for the parent panel.
Controls defined inside a <Triggers> node have the capability to update the contents of an UpdatePanel.
If the ChildrenAsTriggers property is set to false and the UpdateMode property is set to Always, an exception is thrown. The ChildrenAsTriggers property is intended to be used only when the UpdateMode property is set to Conditional.
If the UpdateMode property is set to "Always", the UpdatePanel control’s content is updated on each postback that starts from anywhere on the webpage. This also includes asynchronous postbacks from controls that are inside other UpdatePanel controls, and postbacks from controls which are not inside UpdatePanel controls.
If the UpdateMode property is set to Conditional, the UpdatePanel control’s content is updated when one of the following is true:
1 - When the postback is caused by a trigger for that UpdatePanel control.
2 - When you explicitly call the UpdatePanel control's Update() method.
3 - When the UpdatePanel control is nested inside another UpdatePanel control and the parent panel is updated.
When the ChildrenAsTriggers property is set to true and any child control of the UpdatePanel control causes a postback. Child controls of nested UpdatePanel controls do not cause an update to the outer UpdatePanel control unless they are explicitly defined as triggers for the parent panel.
Controls defined inside a <Triggers> node have the capability to update the contents of an UpdatePanel.
If the ChildrenAsTriggers property is set to false and the UpdateMode property is set to Always, an exception is thrown. The ChildrenAsTriggers property is intended to be used only when the UpdateMode property is set to Conditional.
Q20 - How to control how long an Ajax request may last?
A - Use the ScriptManager's AsyncPostBackTimeout Property.
For example, if you want to debug a web page but you get an error that the page request has timed out, you may set <asp:ScriptManager id="ScriptManager1" runat="server" AsyncPostBackTimeout="9000"/>
where the value specified is in seconds.
For example, if you want to debug a web page but you get an error that the page request has timed out, you may set <asp:ScriptManager id="ScriptManager1" runat="server" AsyncPostBackTimeout="9000"/>
where the value specified is in seconds.
Q21 - What is ASP.NET Futures?
A - ASP.NET AJAX Futures
The new release includes support for managing browser history (Back button support), selecting elements by CSS selectors or classes, and information on accessing “Astoria” Web data services. The Futures (July 2007) release adds:
History support for the Safari browser, inclusion of “titles”, encoding and encrypting of server-side history state and the ability to handle history in the client without a server requirement.
CSS Selectors APIs have been modified to be applicable to W3C recommendations.
A script resource extraction tool that allows you to create script files on disk that originate from embedded resources in assemblies. Important: this version of the browser history feature is now outdated and should not be used. Instead, please download the ASP.NET 3.5 Extensions Preview, which contains the new version.
The new release includes support for managing browser history (Back button support), selecting elements by CSS selectors or classes, and information on accessing “Astoria” Web data services. The Futures (July 2007) release adds:
History support for the Safari browser, inclusion of “titles”, encoding and encrypting of server-side history state and the ability to handle history in the client without a server requirement.
CSS Selectors APIs have been modified to be applicable to W3C recommendations.
A script resource extraction tool that allows you to create script files on disk that originate from embedded resources in assemblies. Important: this version of the browser history feature is now outdated and should not be used. Instead, please download the ASP.NET 3.5 Extensions Preview, which contains the new version.
Q22 - What are limitations of Ajax?
A - 1) An Ajax Web Application tends to confused end users if the network bandwidth is slow, because there is no full postback running. However, this confusion may be eliminated by using an UpdateProgress control in tandem.
2) Distributed applications running Ajax will need a central mechanism for communicating with each other
2) Distributed applications running Ajax will need a central mechanism for communicating with each other
Q23 - How to make sure that contents of an UpdatePanel update only when a partial postback takes place (and not on a full postback)?
A - Make use of ScriptManager.IsInAsyncPostBack property (returns a boolean value)
Q24 - How to trigger a postback on an UpdatePanel from Javascript?
A - Call the __doPostBack function. ASP.NET runtime always creates a javascript function named __doPostBack(eventTarget, eventArgument) when the web page is rendered. A control ID may be passed here to specifically invoke updation of the UpdatePanel.
Q25 - Which request is better with AJAX, Get or Post?
A - AJAX requests should use an HTTP GET request while retrieving data where the data does not change for a given URL requested. An HTTP POST should be used when state is updated on the server. This is in line with HTTP idempotency recommendations and is highly recommended for a consistent web application architecture.
Q26. Is it possible to set session variables from javascript?
It's not possible to set any session variables directly from javascript as it is purely a client side technology. You can use AJAX though to asyncronously...
Cannot parse XML generated by JSP I am generating an XML using JSP, when i run the JSP in IE it shows the XML as per DOM, but when i try to parse it using Javascript , the command xmldoc.documentElement...
This is working code I am using, it might help you. if (!isIE) xmldoc = req.responseXML; else { //IE does not take the responseXML as...
Q27. How do I handle concurrent AJAX requests?With JavaScript you can have more than one AJAX request processing at a single time. In order to insure the proper post processing of code it is recommended that you use JavaScript Closures. The example below shows an XMLHttpRequest object abstracted by a JavaScript object called AJAXInteraction. As arguments you pass in the URL to call and the function to call when the processing is done.
function AJAXInteraction(url, callback) {
var req = init();
req.onreadystatechange = processRequest;
function init() {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
return new ActiveXObject("Microsoft.XMLHTTP");}
}
function processRequest () {
if (req.readyState == 4) {
if (req.status == 200) {
if (callback) callback(req.responseXML);}
}
}
this.doGet = function() {
req.open("GET", url, true);
req.send(null);}
this.doPost = function(body) {
req.open("POST", url, true);
req.setRequestHeader("Content-Type", "
application/x-www-form-urlencoded");
req.send(body);}
}
function makeRequest() {
var ai = new AJAXInteraction("processme",
function() { alert("Doing Post Process");});
ai.doGet();}
The function makeRequest() in the example above creates an AJAXInteraction with a URL to of "processme" and an inline function that will show an alert dialog with the message "Doing Post Process". When ai.doGet() is called the AJAX interaction is initiated and when server-side component mapped to the URL "processme" returns a document which is passed to the callback function that was specified when the AJAXInteraction was created.
Using this closures insures that the proper callback function associated with a specific AJAX interaction is called. Caution should still be taken when creating multiple closure objects in that make XmlHttpRequests as to there is a limited number of sockets that are used to make requests at any given time. Because there are limited number of requests that can be made concurrently. Internet Explorer for example only allows for two concurrent AJAX requests at any given time. Other browsers may allow more but it is generally between three and five requests. You may choose to use pool of AJAXInteraction objects.
One thing to note when making multiple AJAX calls from the client is that the calls are not guaranteed to return in any given order. Having closures within the callback of a closure object can be used to ensure dependencies are processed correctly.
Q28. How do I submit a form or a part of a form without a page refresh?
When creating a form make sure that the "form" element "onSubmit" attribute is set to a JavaScript function that returns false.
<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="submit" id="submit1" value="Update"/>
</>
You can also submit data by associating a function with a form button in a similar way.
<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="button" id="button1" onClick="doAJAXSubmit()" value="Update"/>
</>
Note that the form "onSubmit" attribute is still set. If the user hits the enter key in the text field the form will be submitted so you still need to handle that case.
When updating the page it is recommend you wait to make sure that the AJAX update of the form data was successful before updating the data in the page. Otherwise, the data may not properly update and the user may not know. I like to provide an informative message when doing a partial update and upon a successful AJAX interaction I will then update the page.
Q29. Is the server or the client in control?It depends. With AJAX the answer is more in between. Control can be more centralized in a server-side component or as a mix of client-side and server-side controllers.
* Centralized server-side controller - When having a more centralized controller the key is to make sure the data in client-side page is in sync with that of the server. Some applications may keep all the state on the server and push all updates to client DOM via a simple JavaScript controller.
* Client and server-side controllers - This architecture would use JavaScript to do all presentation related control, event processing, page manipulation, and rendering of model data on the client. The server-side would be responsible for things such as business logic and pushing updated model data to the client. In this case the server would not have intimate knowledge of the presentation short of the initial page that would be sent to the client page request.
There are some use cases where an entire AJAX application can be written in a single page. Keep in mind if you choose this type of architecture that navigation and bookmarking should be considered.
Both methods are viable depending on what you are trying to accomplish. I tend to prefer spreading the control across the client and server.
Q30. Is Ajax just another name for XMLHttpRequest?
No. XMLHttpRequest is only part of the Ajax equation. XMLHttpRequest is the technical component that makes the asynchronous server communication possible; Ajax is our name for the overall approach described in the article, which relies not only on XMLHttpRequest, but on CSS, DOM, and other technologies.
Q31. How do I abort the current XMLHttpRequest?
Just call the abort() method on the request.
Q32. What is the minimum version of PHP that needs to be running in order to use HTML_AJAX?
The oldest PHP version i've fully tested HTML_AJAX is 4.3.11, but it should run on 4.2.0 without any problems. (Testing reports from PHP versions older then 4.3.11 would be appreciated.)
Q33. Why does HTML_AJAX hang on some server installs
If you run into an HTML_AJAX problem only on some servers, chances are your running into a problem with output compression. If the output compression is handled in the PHP config we detect that and do the right thing, but if its done from an apache extension we have no way of knowing its going to compress the body. Some times setting HTML_AJAX::sendContentLength to false fixes the problem, but in other cases you'll need to disabled the extension for the AJAX pages.
I've also seen problems caused by debugging extensions like XDebug, disabling the extension on the server page usually fixes that. Questions dealing with Using HTML_AJAX, and general JavaScript development
Q34. How do I get the XMLHttpRequest object?
Depending upon the browser... if (window.ActiveXObject) { // Internet Explorer http_request = new ActiveXObject("Microsoft.XMLHTTP"); } else if...
Q35. Are there any security issues with AJAX?
JavaScript is in plain view to the user with by selecting view source of the page. JavaScript can not access the local filesystem without the user's permission. An AJAX interaction can only be made with the servers-side component from which the page was loaded. A proxy pattern could be used for AJAX interactions with external services.
You need to be careful not to expose your application model in such as way that your server-side components are at risk if a nefarious user to reverse engineer your application. As with any other web application, consider using HTTPS to secure the connection when confidential information is being exchanged.
Acronyms in .NET
ADO - ActiveX Data Object - Microsoft ActiveX Data Objects (ADO) is a collection of Component Object Model objects for accessing different types of data sources.
AJAX - Asynchronouse Javascript and XML - Ajax is a web development technology used for creating interactive web pages with fast data rendering by enabling partial postbacks on a web page (That means a section of the web page is rendered again, instead of the complete web page. This is achieved using Javascript, XML, JSON (Javascript Notation Language) and the XMLHttpRequest object in javascript.
ASP - Active Server Pages - Microsoft's Server side script engine for creating dynamic web page.
C# - C Sharp - Microsoft Visual C# is an object oriented programming language based on the .NET Framework. It includes features of powerful languages like C++, Java, Delphi and Visual Basic.
CAO - Client Activated Object - Objects created on the server upon the client's request. This is used in Remoting.
CCW - COM Callable Wrapper - This component is used when a .NET component needs to be used in COM.
CIL - Common Intermediate Language - Its actually a low level human readable language implementation of CLI. All .NET-aware languages compile the source oode to an intermediate language called Common Intermediate Language using the language specific compiler.
CLI - Common Language Infrastructure - This is a subset of CLR and base class libraries that Microsoft has submitted to ECMA so that a third-party vendor can build a .NET runtime on another platform.
CLR - Common Language Runtime - It is the main runtime machine of the Microsoft .NET Framework. It includes the implementation of CLI. The CLR runs code in the form of bytes, called as bytecode and this is termed MSIL in .NET.
CLS - Common Language Specification - A type that is CLS compliant, may be used across any .NET language. CLS is a set of language rules that defines language standards for a .NET language and types declared in it. While declaring a new type, if we make use of the [CLSCompliant] attribute, the type is forced to conform to the rules of CLS.
COFF - Common Object File Format - It is a specification format for executables.
COM - Component Object Model - reusable software components. The tribe of COM components includes COM+, Distributed COM (DCOM) and ActiveX® Controls.
CSC.exe - C Sharp Compiler utility
CTS - Common Type System - It is at the core of .NET Framework's cross-language integration, type safety, and high-performance code execution. It defines a common set of types that can be used with many different language syntaxes. Each language (C#, VB.NET, Managed C++, and so on) is free to define any syntax it wishes, but if that language is built on the CLR, it will use at least some of the types defined by the CTS.
DBMS - Database Management System - a software application used for management of databases.
DISCO - Discovery of Web Services. A Web Service has one or more. DISCO files that contain information on how to access its WSDL.
DLL - Dynamic Link Library - a shared reusable library, that exposes an interface of usable methods within it.
DOM - Document Object Model - is a language independent technology that permits scripts to dynamically updated contents of a document (a web page is also a document).
ECMA - European Computer Manufacturer's Association - Is an internation organisation for computer standards.
GC - Garbage Collector - an automatic memory management system through which objects that are not referenced are cleared up from the memory.
GDI - Graphical Device Interface - is a component in Windows based systems, that performs the activity of representing graphical objects and outputting them to output devices.
GAC - Global Assembly Cache - Is a central repository of reusable libraries in the .NET environment.
GUI - Graphic User Interface - a type of computer interface through which user's may interact with the Computer using different types of input & output devices with a graphical interface.
GUID - Globally Unique Identifier - is a unique reference number used in applications to refer an object.
HTTP - Hyper Text Transfer Protocol - is a communication protocol used to transfer information in the internet. HTTP is a request-response protocol between servers and clients.
IDE - Integrated Development Environment - is a development environment with source code editor with a compiler(or interpretor), debugging tools, designer, solution explorer, property window, object explorer etc.
IDL - Interface Definition Language - is a language for defining software components interface.
ILDASM - Intermediate Language Disassembler - The contents of an assembly may be viewed using the ILDASM utility, that comes with the .NET SDK or the Visual Studio.NET. The ildasm.exe tool may also be used in the command line compiler.
IIS - Internet Information Server - Is a server that provides services to websites and even hosts websites.
IL - Intermediate Language - is the compiled form of the .NET language source code. When .NET source code is compiled by the language specific compiler (say we compile C# code using csc.exe), it is compiled to a .NET binary, which is platform independent, and is called Intermediate Language code. The .NET binary also comprises of metadata.
JIT - Just in Time (Jitter) - is a technology for boosting the runtime performance of a system. It converts during runtime, code from one format into another, just like IL into native machine code. Note that JIT compilation is processor specific. Say a processor is X86 based, then the JIT compilation will be for this type of processor.
MBR - MarshallByReference - The caller recieves a proxy to the remote object.
MBV - MarshallByValue - The caller recieves a copy of the object in its own application domain.
MDI - Multiple Document Interface - A window that resides under a single parent window.
MSIL - Microsoft Intermediate Language - now called CIL.
Orcas - Codename for Visual Studio 2008
PE - Portable Executable - an exe format file that is portable.
RAD - Rapid Application Development
RCW - Runtime Callable Wrapper - This component is used when a .NET needs to use a COM component.
SAX - Simple API for XML - It is a serial access parser API for XML. The parser is event driven and the event gets triggered when an XML feature is encountered.
SDK - Software Development Kit
SMTP - Simple Mail Transfer Protocol - a text based protocol for sending mails.
SN.exe - Strong Name Utility - a tool to make strong named assemblies.
SQL - Structured Query Language - a language for management of data in a relational structure.
SOAP - Simple Object Access Protocol - a protocol used for exchange of xml based messages across networks.
TCP - Transmission Control Protocol - data exchange protocol across networks using streamed sockets.
UI - User Interface
URI - Uniform Resource Identifier
URL - Uniform Resource Locator
UDDI - Universal Description, Discovery and Integration - it is a platform independent business registration across the internet.
WAP - Wireless Access Protocol - a protocol that enables access to the internet from mobile phones and PDAs.
WC - Windows Cardspace - Part of .NET 3.0 framework, that enables users to secure and store digital identities of a person, and a provision to a unified interface for choosing the identity for a particular transaction, like logging in to a website.
WCF - Windows Communication Foundation - Part of .NET 3.0 framework, that enables communication between applications across machines.
WF - Windows Workflow Foundation - Part of .NET 3.0 framework, used for defining, execution and management of reusable workflows.
WKO - Well Known Object - These are MBR types whose lifetime is controlled by the server's application domain.
WPF - Windows Presentation Foundation - Part of .NET 3.0 framework, is the graphical subsystem of the .NET 3.0 framework.
WSDL - Web Services Description Language - is an XML based language for describing web services.
WML - Wireless Markup Language - is a content format for those devices that use Wireless Application Protocol.
VB.NET - Visual Basic .NET - .NET based language. Its the .NET implementation of VB6, the most widely used language in the world.
VBC.exe - VB.NET Compiler
VES - Virtual Execution System - It provides the environment for execution of managed code. It provides direct support for a set of built in data types, defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model. To a large extent, the purpose of the VES is to provide the support required to execute the Common Intermediate Language instruction set.
VS - Visual Studio
VSS - Visual Source Safe - An IDE by Microsoft, to maintain source code versions and security.
VSTS - Visual Studio Team Suite - Visual Studio Team System - it is an extended version of Visual Studio .NET. It has a set of collaboration and development tools for software development process.
XML - Extensible Markup Language - is a general purpose well formed markup language.
AJAX - Asynchronouse Javascript and XML - Ajax is a web development technology used for creating interactive web pages with fast data rendering by enabling partial postbacks on a web page (That means a section of the web page is rendered again, instead of the complete web page. This is achieved using Javascript, XML, JSON (Javascript Notation Language) and the XMLHttpRequest object in javascript.
ASP - Active Server Pages - Microsoft's Server side script engine for creating dynamic web page.
C# - C Sharp - Microsoft Visual C# is an object oriented programming language based on the .NET Framework. It includes features of powerful languages like C++, Java, Delphi and Visual Basic.
CAO - Client Activated Object - Objects created on the server upon the client's request. This is used in Remoting.
CCW - COM Callable Wrapper - This component is used when a .NET component needs to be used in COM.
CIL - Common Intermediate Language - Its actually a low level human readable language implementation of CLI. All .NET-aware languages compile the source oode to an intermediate language called Common Intermediate Language using the language specific compiler.
CLI - Common Language Infrastructure - This is a subset of CLR and base class libraries that Microsoft has submitted to ECMA so that a third-party vendor can build a .NET runtime on another platform.
CLR - Common Language Runtime - It is the main runtime machine of the Microsoft .NET Framework. It includes the implementation of CLI. The CLR runs code in the form of bytes, called as bytecode and this is termed MSIL in .NET.
CLS - Common Language Specification - A type that is CLS compliant, may be used across any .NET language. CLS is a set of language rules that defines language standards for a .NET language and types declared in it. While declaring a new type, if we make use of the [CLSCompliant] attribute, the type is forced to conform to the rules of CLS.
COFF - Common Object File Format - It is a specification format for executables.
COM - Component Object Model - reusable software components. The tribe of COM components includes COM+, Distributed COM (DCOM) and ActiveX® Controls.
CSC.exe - C Sharp Compiler utility
CTS - Common Type System - It is at the core of .NET Framework's cross-language integration, type safety, and high-performance code execution. It defines a common set of types that can be used with many different language syntaxes. Each language (C#, VB.NET, Managed C++, and so on) is free to define any syntax it wishes, but if that language is built on the CLR, it will use at least some of the types defined by the CTS.
DBMS - Database Management System - a software application used for management of databases.
DISCO - Discovery of Web Services. A Web Service has one or more. DISCO files that contain information on how to access its WSDL.
DLL - Dynamic Link Library - a shared reusable library, that exposes an interface of usable methods within it.
DOM - Document Object Model - is a language independent technology that permits scripts to dynamically updated contents of a document (a web page is also a document).
ECMA - European Computer Manufacturer's Association - Is an internation organisation for computer standards.
GC - Garbage Collector - an automatic memory management system through which objects that are not referenced are cleared up from the memory.
GDI - Graphical Device Interface - is a component in Windows based systems, that performs the activity of representing graphical objects and outputting them to output devices.
GAC - Global Assembly Cache - Is a central repository of reusable libraries in the .NET environment.
GUI - Graphic User Interface - a type of computer interface through which user's may interact with the Computer using different types of input & output devices with a graphical interface.
GUID - Globally Unique Identifier - is a unique reference number used in applications to refer an object.
HTTP - Hyper Text Transfer Protocol - is a communication protocol used to transfer information in the internet. HTTP is a request-response protocol between servers and clients.
IDE - Integrated Development Environment - is a development environment with source code editor with a compiler(or interpretor), debugging tools, designer, solution explorer, property window, object explorer etc.
IDL - Interface Definition Language - is a language for defining software components interface.
ILDASM - Intermediate Language Disassembler - The contents of an assembly may be viewed using the ILDASM utility, that comes with the .NET SDK or the Visual Studio.NET. The ildasm.exe tool may also be used in the command line compiler.
IIS - Internet Information Server - Is a server that provides services to websites and even hosts websites.
IL - Intermediate Language - is the compiled form of the .NET language source code. When .NET source code is compiled by the language specific compiler (say we compile C# code using csc.exe), it is compiled to a .NET binary, which is platform independent, and is called Intermediate Language code. The .NET binary also comprises of metadata.
JIT - Just in Time (Jitter) - is a technology for boosting the runtime performance of a system. It converts during runtime, code from one format into another, just like IL into native machine code. Note that JIT compilation is processor specific. Say a processor is X86 based, then the JIT compilation will be for this type of processor.
MBR - MarshallByReference - The caller recieves a proxy to the remote object.
MBV - MarshallByValue - The caller recieves a copy of the object in its own application domain.
MDI - Multiple Document Interface - A window that resides under a single parent window.
MSIL - Microsoft Intermediate Language - now called CIL.
Orcas - Codename for Visual Studio 2008
PE - Portable Executable - an exe format file that is portable.
RAD - Rapid Application Development
RCW - Runtime Callable Wrapper - This component is used when a .NET needs to use a COM component.
SAX - Simple API for XML - It is a serial access parser API for XML. The parser is event driven and the event gets triggered when an XML feature is encountered.
SDK - Software Development Kit
SMTP - Simple Mail Transfer Protocol - a text based protocol for sending mails.
SN.exe - Strong Name Utility - a tool to make strong named assemblies.
SQL - Structured Query Language - a language for management of data in a relational structure.
SOAP - Simple Object Access Protocol - a protocol used for exchange of xml based messages across networks.
TCP - Transmission Control Protocol - data exchange protocol across networks using streamed sockets.
UI - User Interface
URI - Uniform Resource Identifier
URL - Uniform Resource Locator
UDDI - Universal Description, Discovery and Integration - it is a platform independent business registration across the internet.
WAP - Wireless Access Protocol - a protocol that enables access to the internet from mobile phones and PDAs.
WC - Windows Cardspace - Part of .NET 3.0 framework, that enables users to secure and store digital identities of a person, and a provision to a unified interface for choosing the identity for a particular transaction, like logging in to a website.
WCF - Windows Communication Foundation - Part of .NET 3.0 framework, that enables communication between applications across machines.
WF - Windows Workflow Foundation - Part of .NET 3.0 framework, used for defining, execution and management of reusable workflows.
WKO - Well Known Object - These are MBR types whose lifetime is controlled by the server's application domain.
WPF - Windows Presentation Foundation - Part of .NET 3.0 framework, is the graphical subsystem of the .NET 3.0 framework.
WSDL - Web Services Description Language - is an XML based language for describing web services.
WML - Wireless Markup Language - is a content format for those devices that use Wireless Application Protocol.
VB.NET - Visual Basic .NET - .NET based language. Its the .NET implementation of VB6, the most widely used language in the world.
VBC.exe - VB.NET Compiler
VES - Virtual Execution System - It provides the environment for execution of managed code. It provides direct support for a set of built in data types, defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model. To a large extent, the purpose of the VES is to provide the support required to execute the Common Intermediate Language instruction set.
VS - Visual Studio
VSS - Visual Source Safe - An IDE by Microsoft, to maintain source code versions and security.
VSTS - Visual Studio Team Suite - Visual Studio Team System - it is an extended version of Visual Studio .NET. It has a set of collaboration and development tools for software development process.
XML - Extensible Markup Language - is a general purpose well formed markup language.
Thanks for sharing these web development tools.
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