At each stage of the page life cycle, the page raises some events, which could be coded. An event handler is basically a function or subroutine, bound to the event, using declarative attributes like Onclick or handle.
Following are the page life cycle events:
PreInit . PreInit is the first event in page life cycle. It checks the IsPostBack property and determines whether the page is a postback. It sets the themes and master pages, creates dynamic controls and gets and sets profile property values. This event can be handled by overloading the OnPreInit method or creating a Page_PreInit handler.
Init . Init event initializes the control property and the control tree is built. This event can be handled by overloading the OnInit method or creating a Page_Init handler.
InitComplete . InitComplete event allows tracking of view state. All the controls turn on view-state tracking.
LoadViewState . LoadViewState event allows loading view state information into the controls.
LoadPostData . during this phase, the contents of all the input fields defined with the
PreLoad . PreLoad occurs before the post back data is loaded in the controls. This event can be handled by overloading the OnPreLoad method or creating a Page_PreLoad handler.
Load . the Load event is raised for the page first and then recursively for all child controls. The controls in the control tree are created. This event can be handled by overloading the OnLoad method or creating a Page_Load handler.
LoadComplete . the loading process is completed, control event handlers are run and page validation takes place. This event can be handled by overloading the OnLoadComplete method or creating a Page_LoadComplete handler.
PreRender . the PreRender event occurs just before the output is rendered. By handling this event, pages and controls can perform any updates before the output is rendered.
PreRenderComplete . as the PreRender event is recursively fired for all child controls, this event ensures the completion of the pre-rendering phase.
SaveStateComplete . state of control on the page is saved. Personalization, control state and view state information is saved. The HTML markup is generated. This stage can be handled by overriding the Render method or creating a Page_Render handler.
UnLoad . the UnLoad phase is the last phase of the page life cycle. It raises the UnLoad event for all controls recursively and lastly for the page itself. Final cleanup is done and all resources and references, such as database connections, are freed. This event can be handled by modifying the OnUnLoad method or creating a Page_UnLoad handler.
ASP.Net Page Life Cycle:
When a page is requested, it is loaded into the server memory, processed and sent to the browser. Then it is unloaded from the memory. At each of this steps, methods and events are available, which could be overridden according to the need of the application. In other words, you can write your own code to override the default code.
The Page class creates a hierarchical tree of all the controls on the page. All the components on the page, except the directives are part of this control tree. You can see the control tree by adding trace= "true" to the Page directive. We will cover page directives and tracing under 'directives' and 'error handling'.
The page life cycle phases are:
Initialization
Instantiation of the controls on the page
Restoration and maintenance of the state
Execution of the event handler codes
Page rendering
Understanding the page cycle helps in writing codes for making some specific thing happen at any stage of the page life cycle. It also helps in writing custom controls and initializing them at right time, populate their properties with view-state data and run control behavior code.
Following are the different stages of an ASP.Net page:
Page request . when ASP.Net gets a page request, it decides whether to parse and compile the page or there would be a cached version of the page; accordingly the response is sent
Starting of page life cycle . at this stage, the Request and Response objects are set. If the request is an old request or post back, the IsPostBack property of the page is set to true. The UICulture property of the page is also set.
Page initialization . at this stage, the controls on the page are assigned unique ID by setting the UniqueID property and themes are applied. For a new request postback data is loaded and the control properties are restored to the view-state values.
Page load . at this stage, control properties are set using the view state and control state values.
Validation . Validate method of the validation control is called and if it runs successfully, the IsValid property of the page is set to true.
Postback event handling . if the request is a postback (old request), the related event handler is called.
Page rendering . at this stage, view state for the page and all controls are saved. The page calls the Render method for each control and the output of rendering is written to the OutputStream class of the Page's Response property.
Unload . the rendered page is sent to the client and page properties, such as Response and Request are unloaded and all cleanup done.
In VS 2012 we got UI for Baseless code merge But for VS2010 we need to use command line tool.
When you would like to use Source Control Merge Wizard in Visual Studio (e.g.; by right clicking a branch folder then going to 'Branching and Merging' -> 'Merge') and you find that the intended target is not in the 'Target branch' selection that means the source does not have any relationship with the target. You can proof this from 'Branching and Merging' -> 'View Hierarchy' option. This is when we need to do baseless merge operation.
To perform this operation, we can use the merge command on TFS command line tool. The syntax is
- path can be physical folder or source control location. - [versionspec] can be a changeset, range of (inclusive) changesets separated by '~' character, a label, a date or versions. If we don't specify /version then it will merge all changes.
Below are some examples: - Merge all changes from branch to trunk
If it is happened that the merge causing a lot of checkouts of unmodified files then we can use TFS Power Tools to undo the checkouts.
D:\My Project\trunk>tfpt uu /r /noget *
'uu' - undo unchanged '/r' - recursive '/noget' - do the operation without getting latest
If this one is still not working and leaving a lot of unmodified files checked out, we have to do Undo Changes manually. This can be done through the Pending Changes view, right click on any file from the list then select 'Undo'. The Undo Pending Changes dialog will pop up. Check all the files then click 'Undo Changes' button. A confirmation dialog with the message "... has changed. Undo check-out and discard changes?' will be shown. Click 'No to All' button. Then all unmodified files will be reverted while the modified ones from the merge operation stay.
Tracing mechanism in Windows Communication Foundation is based on the
classes that resides in System.Diagnostic namespace.Important classes are Trace,
TraceSource and TraceListener.
Following are the steps to enable tracing
in WCF:
1. Configuring WCF to emit tracing information/Define Trace Source,
we have the following options:
System.ServiceModel
System.ServiceModel.MessageLogging
System.ServiceModel.IdentityModel
System.ServiceModel.Activation
System.Runtime.Serialization
System.IO.Log
Cardspace
In configuration file, we will define a source to
enable this configuration as follows:
2. Setting Tracing Level, we have the
following available options, we need to set this tracing level to available
options other than default "Off":
Off
Critical
Error
Warning
Information
Verbose
ActivityTracing
All
In configuration file, we can choose above
values for switchValue attribute as follows:
switchValue=”Information”>
3. Configuring a trace listener
For configuring a trace listener, we will add
following to config file.
type="System.Diagnostics.XmlWriterTraceListener"
initializeData="d:\logs\messages.svclog"
/>
logEntireMessage: By default,
only the message header is logged but if we set it to true, entire message
including message header as well as body will be
logged. logMalformedMessages: this option log messages those
are rejected by WCF stack at any stage are known as malformed
messages. logMessagesAtServiceLevel: messages those are about
to enter or leave user code. logMessagesAtTransportLevel:
messages those are about to encode or decode. maxMessagesToLog:
maximum quota for messages. Default value is
10000. maxSizeOfMessageToLog: message size in bytes.
Putting all this together, configuration file
will appear like this.
Note: In this case, information will be
buffered and not published to file automatically, So, we can set the autoflush
property of the trace under sources as follows:
Simplex Data in a simplex channel is always one way.
Simplex channels are not often used because it is not possible to send back
error or control signals to the transmit end.
It's like a one way street. An example of simplex is Television,
or Radio. The simplex channel also corresponds directly to Shannon's model of communication discussed
earlier.
Half Duplex A half-duplex channel can send and
receive, but not at the same time. It's like a one-lane bridge where two way
traffic must give way in order to cross. Only one end transmits at a time, the
other end receives. In addition, it is possible to perform error detection and
request the sender to retransmit information that arrived corrupted. In some
aspects, you can think of Internet surfing as
being half-duplex, as a user issues a request for a web document, then that
document is downloaded and displayed before the user issues another request.
Another example of half-duplex is talk-back radio, and CB Radio
(Citizens Band). You might have seen movies where truckies (drivers of very big
trucks) communicate to each other, and when they want the other person to speak
they say "over". This is because only one person can talk at a
time.
Full Duplex Data can travel in both directions
simultaneously. There is no need to switch from transmit to receive mode like in
half duplex. Its like a two lane bridge on a two-lane highway. Have you ever
watched these television talk shows where the host has a number of people on the
show, and they all try to talk at once. Well, that's full duplex!
Simplex
