Can server initiate update of client pages ?

[Curt_C [MVP]]

the clientside controls, like the textbox, will have to "AutoPostBack" and make another trip to the server to get the requested information.

ASP.NET can not natively be run on a *nix server. There are some "workarounds" if you search this group but it's not really recommended.

The browser SHOULD be irrelevant but most ASP.NET sites require that javascript be supported on the client's browser.


--
Curt Christianson
Owner/Lead Developer, DF-Software
Site: http://www.Darkfalz.com
Blog: http://blog.Darkfalz.com


Hi,
I am a newby in ASP.NET, and till now wrote only simple "classic" WEB-sites.

But - the time came, and now I need that:

1. Server will "listen" for some events on its local machine
2. According to event received (say - event ID), it will update client pages, that need updating based on this ID (if currently there exist clients that are interesting in specific ID).

The good example of such site - airport flight information, when client selects some specific flight(s), and want to see automatic updates of displayed information withOUT pushing on "UPDATE" button (or timer at client side that sends update requests).

My questions are:

1. What ASP.NET mechanism can I use to implement above thing ?
2. If this is possible, can such WEB-site be published on UNIX-based Internet Server ?
3. Can it be seen from UNIX-based browser ?

Thanks,

Zvi

 

[Zvi Danovich]

Hi,
I am a newby in ASP.NET, and till now wrote only simple "classic" WEB-sites.

But - the time came, and now I need that:

1. Server will "listen" for some events on its local machine
2. According to event received (say - event ID), it will update client pages, that need updating based on this ID (if currently there exist clients that are interesting in specific ID).

The good example of such site - airport flight information, when client selects some specific flight(s), and want to see automatic updates of displayed information withOUT pushing on "UPDATE" button (or timer at client side that sends update requests).

My questions are:

1. What ASP.NET mechanism can I use to implement above thing ?
2. If this is possible, can such WEB-site be published on UNIX-based Internet Server ?
3. Can it be seen from UNIX-based browser ?

Thanks,

Zvi

 

[Mark Rae]

1. What ASP.NET mechanism can I use to implement above thing ?

Place the following in your page's HTML header:
<META HTTP-EQUIV="REFRESH" CONTENT="5">

It will force the page to refresh itself every 5 seconds.

2. If this is possible, can such WEB-site be published on UNIX-based

Internet Server ?

The above will work in any web server because it is raw HTML. However,
ASP.NET is designed to run only on the Windows platform.

3. Can it be seen from UNIX-based browser ?

The browser is irrelevant.

 

[Zvi Danovich]

Dear Curt,

As I see the description of AutoPostBack property -
Use the AutoPostBack property to specify whether an automatic postback to the server will occur whenever the user modifies the text in the TextBox control and then tabs out of the control. Note Postback only occurs when the text box loses focus after the contents are changed.
- it causes update when the control loses focus. But, to my opinion, this is NOT what I want !

Let me ask once more, what I need:

1. User selects ID of update type - (say, flight number) - and sends (submits) it to server. The server saves all submitted IDs and can identify them with clients (may be, by IP address ?).
2. User moves the browser window to the screen corner, and works with other applications.
3. Server has general message loop (is it possible ?), and when it receives message with specific ID, it checks, if there are clients, that are interesting with this ID. If such clients are found, server updates their pages. It can occur many times for the same client - so, the user will see the window that is updated many time by itself.

Is above processing possible ?

Thanks,

Zvi

"Curt_C [MVP]" <software_AT_darkfalz.com> wrote in message the clientside controls, like the textbox, will have to "AutoPostBack" and make another trip to the server to get the requested information.

ASP.NET can not natively be run on a *nix server. There are some "workarounds" if you search this group but it's not really recommended.

The browser SHOULD be irrelevant but most ASP.NET sites require that javascript be supported on the client's browser.


--
Curt Christianson
Owner/Lead Developer, DF-Software
Site: http://www.Darkfalz.com
Blog: http://blog.Darkfalz.com


Hi,
I am a newby in ASP.NET, and till now wrote only simple "classic" WEB-sites.

But - the time came, and now I need that:

1. Server will "listen" for some events on its local machine
2. According to event received (say - event ID), it will update client pages, that need updating based on this ID (if currently there exist clients that are interesting in specific ID).

The good example of such site - airport flight information, when client selects some specific flight(s), and want to see automatic updates of displayed information withOUT pushing on "UPDATE" button (or timer at client side that sends update requests).

My questions are:

1. What ASP.NET mechanism can I use to implement above thing ?
2. If this is possible, can such WEB-site be published on UNIX-based Internet Server ?
3. Can it be seen from UNIX-based browser ?

Thanks,

Zvi

 

[Mark Rae]

Your answer means - polling. But polling increases system loading and is
highly NOT recommended. Are you sure that polling is the only solution ?

AFAIK - see also Eliyahu's response...

 

[Eliyahu Goldin]

Zvi,

You can get the browser to refresh the page periodically. You can't get the the server to initiate refresh.

Eliyahu
Dear Curt,

As I see the description of AutoPostBack property -
Use the AutoPostBack property to specify whether an automatic postback to the server will occur whenever the user modifies the text in the TextBox control and then tabs out of the control. Note Postback only occurs when the text box loses focus after the contents are changed.
- it causes update when the control loses focus. But, to my opinion, this is NOT what I want !

Let me ask once more, what I need:

1. User selects ID of update type - (say, flight number) - and sends (submits) it to server. The server saves all submitted IDs and can identify them with clients (may be, by IP address ?).
2. User moves the browser window to the screen corner, and works with other applications.
3. Server has general message loop (is it possible ?), and when it receives message with specific ID, it checks, if there are clients, that are interesting with this ID. If such clients are found, server updates their pages. It can occur many times for the same client - so, the user will see the window that is updated many time by itself.

Is above processing possible ?

Thanks,

Zvi

"Curt_C [MVP]" <software_AT_darkfalz.com> wrote in message the clientside controls, like the textbox, will have to "AutoPostBack" and make another trip to the server to get the requested information.

ASP.NET can not natively be run on a *nix server. There are some "workarounds" if you search this group but it's not really recommended.

The browser SHOULD be irrelevant but most ASP.NET sites require that javascript be supported on the client's browser.


--
Curt Christianson
Owner/Lead Developer, DF-Software
Site: http://www.Darkfalz.com
Blog: http://blog.Darkfalz.com


Hi,
I am a newby in ASP.NET, and till now wrote only simple "classic" WEB-sites.

But - the time came, and now I need that:

1. Server will "listen" for some events on its local machine
2. According to event received (say - event ID), it will update client pages, that need updating based on this ID (if currently there exist clients that are interesting in specific ID).

The good example of such site - airport flight information, when client selects some specific flight(s), and want to see automatic updates of displayed information withOUT pushing on "UPDATE" button (or timer at client side that sends update requests).

My questions are:

1. What ASP.NET mechanism can I use to implement above thing ?
2. If this is possible, can such WEB-site be published on UNIX-based Internet Server ?
3. Can it be seen from UNIX-based browser ?

Thanks,

Zvi

 

[Zvi Danovich]

Mark, hi,

Your answer means - polling. But polling increases system loading and is
highly NOT recommended. Are you sure that polling is the only solution ?

 

[Zvi Danovich]

Eliyahu, hi,

See, please my queston to Mark Rae in this thread.
Zvi,

You can get the browser to refresh the page periodically. You can't get the the server to initiate refresh.

Eliyahu
Dear Curt,

As I see the description of AutoPostBack property -
Use the AutoPostBack property to specify whether an automatic postback to the server will occur whenever the user modifies the text in the TextBox control and then tabs out of the control. Note Postback only occurs when the text box loses focus after the contents are changed.
- it causes update when the control loses focus. But, to my opinion, this is NOT what I want !

Let me ask once more, what I need:

1. User selects ID of update type - (say, flight number) - and sends (submits) it to server. The server saves all submitted IDs and can identify them with clients (may be, by IP address ?).
2. User moves the browser window to the screen corner, and works with other applications.
3. Server has general message loop (is it possible ?), and when it receives message with specific ID, it checks, if there are clients, that are interesting with this ID. If such clients are found, server updates their pages. It can occur many times for the same client - so, the user will see the window that is updated many time by itself.

Is above processing possible ?

Thanks,

Zvi

"Curt_C [MVP]" <software_AT_darkfalz.com> wrote in message the clientside controls, like the textbox, will have to "AutoPostBack" and make another trip to the server to get the requested information.

ASP.NET can not natively be run on a *nix server. There are some "workarounds" if you search this group but it's not really recommended.

The browser SHOULD be irrelevant but most ASP.NET sites require that javascript be supported on the client's browser.


--
Curt Christianson
Owner/Lead Developer, DF-Software
Site: http://www.Darkfalz.com
Blog: http://blog.Darkfalz.com


Hi,
I am a newby in ASP.NET, and till now wrote only simple "classic" WEB-sites.

But - the time came, and now I need that:

1. Server will "listen" for some events on its local machine
2. According to event received (say - event ID), it will update client pages, that need updating based on this ID (if currently there exist clients that are interesting in specific ID).

The good example of such site - airport flight information, when client selects some specific flight(s), and want to see automatic updates of displayed information withOUT pushing on "UPDATE" button (or timer at client side that sends update requests).

My questions are:

1. What ASP.NET mechanism can I use to implement above thing ?
2. If this is possible, can such WEB-site be published on UNIX-based Internet Server ?
3. Can it be seen from UNIX-based browser ?

Thanks,

Zvi

 

[Eliyahu Goldin]

Well, that what web servers are all about - to serve client's requests.
Other way around, keeping clients sessions contradicts scalability. Can I
ask who doesn't recommend polling?

Eliyahu

 

[Zvi Danovich]

Eliyahu, hi,

Let's think in a very simple way: if I want to update client page not late
than 5 sec after change, I must poll each 5 sec. If server receives one
change event in 1 min, it means, that polling will cause more than 10
requests during the time of one possible update in "server=>client"
direction. To my opinion, it is obvious, what can be recommended.

And if we continue our discussion, explain me, please: if I know IP address
of client (and I can identify it !) - are you sure that server cannot update
the client using this address ? It seems to be very strange ...

 

[Eliyahu Goldin]

Zvi,

Again, the server is made and optimized specially for this sort of
tasks.Your arithmetic is not good here since the server and the client are
not equal parties. One is made to be a server, and another is made to be a
client.

IP address of the sender is not enough to initiate reverse communication,
even you don't mind writing your own software that will try doing this.
Consider a typical case when a user is on the corporal Intranet and his
machine doesn't have any external IP address. Also consider all variety of
security settings, firewalls.

Eliyahu

 

[Curt_C [MVP]]

You are after PUSH technology, Web is a Request/Response system.
Wrong technology for what you are after.

 

[Lucas Tam]

Your answer means - polling. But polling increases system loading and is
highly NOT recommended. Are you sure that polling is the only solution ?

Build an applet - either with Java or Winforms hosted in IE.

 

[Lucas Tam]

And if we continue our discussion, explain me, please: if I know IP
address of client (and I can identify it !) - are you sure that server
cannot update the client using this address ? It seems to be very
strange ...

You're not a web developer are you.

 

[Mark Rae]

And if we continue our discussion, explain me, please: if I know IP address
of client (and I can identify it !) - are you sure that server cannot update
the client using this address ? It seems to be very strange ...

Imagine the havoc that hackers could wreak with that sort of capability!

 

[Mark Rae]

You're not a web developer are you.

ROTFLMAO!

 

[Zvi Danovich]

Lucas, hi,

You are right - I'm not a WEB developer.
Can you hint, how Java or Winforms applet can help me in my goal without
polling ?
All what I have seen in above correspondence - that it is impossible, and
when I have believed - you write about applets ...

 

[Lucas Tam]

Can you hint, how Java or Winforms applet can help me in my goal without
polling ?
All what I have seen in above correspondence - that it is impossible, and
when I have believed - you write about applets ...

Applets are small programs that run on the client. With an applet, you can
initiate data updates with more control. Also, with an applet, you can
cache data to the user's computer, so you don't need to poll as often.

But since the user is remote and there is always a lag between user
requests, you'll need to do database checks before inserting data.