Server push / Client pull
Hi,
Please let me know about Server push and Client pull . When this has to be needed. please explain.
Thanks in advance.
google ...
Similar Messages
-
FDS for server push + client to client
Just want to double check - if I was to create a chat like
app in Flex - where new messages are "pushed" to clients, this
would require FDS.Using FDS would be the far easiest way to implement a chat
application.
Theoretically you could implement a chat application without
FDS by having each client poll the server for messages for new
messages for that client using HTTPService or WebService.
You can also do "poor man's data push" using a long-lasting
HTTP request - in this pattern each client posts an HTTP request
that it doesn't expect and immediate response to - when the server
has a message for the client is sends the response (perhaps a long
time later). In the client's event handler for the response the
client posts another request (so that the server has a means of
"pushing" data to the client). This is how Blackberry-style email
works in Windows Mobile (in the absence of a proper data push
protocol).
Sean
Neville's Introduction to the Flex Message Service has a good
example of how to write a chat application in FDS.
Graeme Harker's Flex.NET
Blog -
Server Push pushing data to clients
Need some ideas.
I have been hunting around for info on a simple/clean method
to push data out to clients. Client could be a Java application or maybe an applet. Solution must easily go through firewalls
In either case I want the client to startup, register with the server
and start receiving data. Without further user intervention.
Whatever, scheme is used must be able to deal with network
disconnects.
I have looked at Pushlets, the article was 2 years old and I don't see
any recent postings on Pushlets. So maybe that is not the way to go.
I guess my other choice is JMS. SonicMQ?
Server Push using Netscape?
Or are there other options.
Many thanks for your feedback.
KDHave you considered J2ME.
J2ME and WAP Push can be complementary. but for WAP Push to work the devices or the browsers in the devices have to be WAP 1.2 complaint.
more details can be found at http://devforum.openwave.com
hope this helps.
williams -
Hi AnyOne!
I have a servlet, and a database . If a column in my table gets updated I
want all of my clients who are connected to it , to see the refreshed value
without click any refresh/Reload button on the browser. A kind of
Server-Push.
That is, If one client makes changes, then all of the other clients on the
web should get intimated.
How can I achieve this ?
thanks
vikas
I read the OP's message and imediately thought oh, cool, MVC candidate :-) If I wanna talk about MVC I would prefer Sun's Design Patterns group.
Kumar.
[email protected] wrote:
> "Mettu Kumar" <[email protected]> wrote in message
> news:[email protected]...
> > Ryan,
> >
> > I was not commenting on MVC pattern. I am talking about the problems
> > pushlets implementation could potentially cause.
>
> Mettu, we completly crossed paths my friend. I read the OP's message and
> imediately thought oh, cool, MVC candidate :-) Silly me! I understand what
> you are talking about now :-)
>
> > 1. If you are serving 10,000 clients, probably a given instance your
> server will
> > be serving 100 or 1000 of the them. but with pushlets you have 10, 000
> > conenctions open siumultaneously and your server is serving all the client
> 100%
> > of the time.
>
> No, you're right that isn't good.
>
> > Do you think this would scale? Imagine the number of threads on server.
> > 2. This could potentially bring down the web server you are using.
> >
>
> It would scale right up to the time the server came crashing down :-) Yes,
> if the server kept a single connection, thread of execution, open to every
> client while the client was running that would be not so hot indeed,
> especially if your clients increased exponentially. This is precisely why I
> like the callback method on each client, kind of a pain to implement though.
>
> >
> > Kumar.
> >
> > [email protected] wrote:
> >
> > > I wasn't referring to the article on pushlets you mentioned when I said
> the
> > > idea of MVC was a valid one, nor have I read the article as I respond
> but
> > > heres the idea I was describing which is based on the concept of MVC.
> It
> > > provides perfectly for the scenario the OP described IMO. I think, at
> least
> > > based on what I've seen, that the notion of MVC in the J2EE sector is
> used
> > > mostly as a means to seperate business logic from presentation logic.
> It
> > > doesn't allow for any mechanisms to notify the ``views" when data
> ``model"
> > > changes. This is no big deal I guess for most applications but it does
> > > break the MVC paradigm IMO. To aleiviate this problem we incorporate an
> > > observer pattern to notify each subscribing view when the model changes.
> > > There really isn't any difference in my mind between push and pull where
> > > pull is a standard RFC 2616 request and push is a simple callback to the
> > > object registered with the controller (servlet, jsp). If the server can
> > > handle a thousand or so concurrent requests why couldn't it handle a
> > > thousand concurrent callbacks. You could probably improve this by
> > > multi-threading the controller. Just some thoughts I would like to hear
> > > yours :-)
> > >
> > > ~Ryan
> > >
> > > "Mettu Kumar" <[email protected]> wrote in message
> > > news:[email protected]...
> > > > Ryan,
> > > >
> > > > Did you ever try to use to Pushlets serving thousands of clients?
> > > > Why did you think its a good design? If you feel its a good design,
> let
> > > us
> > > > know whats good about it.
> > > >
> > > > Kumar.
> > > >
> > > > [email protected] wrote:
> > > >
> > > > > "Mettu Kumar" <[email protected]> wrote in message
> > > > > news:[email protected]...
> > > > > > Vikas,
> > > > > >
> > > > > > There was a article about the same in java world a while back.
> > > > > > http://www.javaworld.com/javaworld/jw-03-2000/jw-03-pushlet.html
> > > > > >
> > > > > > But I believe this is bad design. I don't think using opened HTTP
> > > > > Connections
> > > > > > to do a real time operation is not a good Idea. What if you are
> > > serving
> > > > > couple
> > > > > > of hundred clients?
> > > > > >
> > > > > > Kumar.
> > > > > >
> > > > >
> > > > > It's a perfectly valid design. OP, check out MVC and the observer
> > > design
> > > > > pattern I think you'll find what you're looking for there.
> > > > >
> > > > > ~Ryan
> > > > >
> > > > > > Vikas Jolly wrote:
> > > > > >
> > > > > > > Hi AnyOne!
> > > > > > >
> > > > > > > I have a servlet, and a database . If a column in my table gets
> > > updated
> > > > > I
> > > > > > > want all of my clients who are connected to it , to see the
> > > refreshed
> > > > > value
> > > > > > > without click any refresh/Reload button on the browser. A kind
> of
> > > > > > > Server-Push.
> > > > > > > That is, If one client makes changes, then all of the other
> clients
> > > on
> > > > > the
> > > > > > > web should get intimated.
> > > > > > >
> > > > > > > How can I achieve this ?
> > > > > > >
> > > > > > > thanks
> > > > > > > vikas
> > > > > >
> > > >
> > > >
> >
-
How to use server push technology
I need to write a Chatroom by using Server-push technology. Who would like to offer some information about this technology for me? Thanks!!
Define "server-push" technology.client-pull is where the client pulls, via a specific request, information from the server.
Server-push is where the server pushes information to a client when that information becomes available. The client does not initiate the exchange. -
I read somewhere that Flex Data Services provides Server-Push
functionality. That is, the server starts a conversation with the
client. It's obvious that, In order to such thing ocurr, there has
to be a persistent connection between server and client.
I've being reading about Data Management Service to learn how
to implement this Server-Push and all I see is about a method
called Fill() that is thriggered from the client and syncronizes
it's data with the server. But it's not server-push
Does it really exist?Hi,
When you create a DataService and fill your collection. The
collection becomes managed. You don't have to call fill again if
there is any change in the data. Server pushs updates to clients
when the client's dataservice is using rtmp channel. It is a live
connection between the server and the client. For example,
you fill(collection, "hqsql", from products where price <
100). If one of the product's price increases, server push a
message to your collection to remove it. If a product's product's
price decrease, it will be added to the collection. The push is
happened based on your fill method.
William Chan -
Hi AnyOne!
I have a jsp, and a database . If a column in my table gets updated I
want all of my clients who are connected to it , to see the refreshed value
without click any refresh/Reload button on the browser. A kind of
Server-Push.
That is, If one client makes changes, then all of the other clients on the
web should get intimated.
How can I achieve this ?
thanks
vikas
Vikas,
There was a article about the same in java world a while back.
http://www.javaworld.com/javaworld/jw-03-2000/jw-03-pushlet.html
But I believe this is bad design. I don't think using opened HTTP Connections
to do a real time operation is not a good Idea. What if you are serving couple
of hundred clients?
Kumar.
Vikas Jolly wrote:
> Hi AnyOne!
>
> I have a jsp, and a database . If a column in my table gets updated I
> want all of my clients who are connected to it , to see the refreshed value
> without click any refresh/Reload button on the browser. A kind of
> Server-Push.
> That is, If one client makes changes, then all of the other clients on the
> web should get intimated.
>
> How can I achieve this ?
>
> thanks
> vikas
-
Implementing Server Push using LCDS 2.6
Hi All,
We have created an application where we are using polling to get certain constant updates. Now this polling is client polling wherein the client polls the server at regular intervals to get the fresh data for certain actions.
Now we wish to take this to another level and implement Server Data Push so that the client does not keep polling unnecessarily and the server notifies the client as and when the data gets updated with the server. For this we have the DataService Transaction class that needs to be implemented.
But there are a couple of questions that are in my mind regarding this technology. It would be great if someone could answer them.
My questions are:
1) Does the LCDS server know which client to push data to in case of multiple clients looking at the same data scenario. e.g. Two clients A and B are looking at the same data. A performs an action and that action needs some time to get completed at the server. Now in case we use Server Data Push, will the LCDS be intelligent enough to send the message on completion of the requested activity to only A and not B.
2) In order to push data to the client, the server will invoke some method which will return the desired data to te client. How do we keep the parameters registered with the server that this method would need while getting invoked. SInce, the call to the method will not be client initiated, how does the server know what parameters to be passed to the method in order to invoke it. How will this work in a multi-user looking at the same data/screen scenario.
The answers to these questions will really help us. In case anyone is well versed with this technology, please pitch in to give your inputs.
Many Thanks.
Regards,
ShallyHi,
As also, suggested by you, we were thinking of using an RTMP channel only for this since its a two way socket that establishes a communication channel between the client and the server and then helps keep messages moving to and fro.
We have successfully implemented RTMP channel and achieved the following functionalities.
1) A client initiated change which gets propagated to the server and then to all the clients.
2) Server push to all the clients.
Now our last step is to implement data push to a particular client. As told by you, we will use the client id but we have some doubts and questions regarding this since we do not have the code examples or anything that could help us in implementing the same.
I would therefore request you to kindly lead us on the following fronts:
1) Is the client id the one that is part of the request- response thread, I saw a client id being printed in the logs when a request is made and the response comes.
2) What code needs to be written on the server side to extract this client id once a call is made so that it can keep this client id with itself to push a message later on.
3) What methods or API are available to be used to push this message to a particular client? Do we need to call the fill method of a particular client using the client id parameter and inform the client that its requested job has been done.
For (3) is the Messaging(Publish and Subscribe model) the right way to go??
It would be great if you could provide us some code snippets just to give us an idea from where we can take it up ourselves.
Looking forward to hear from you.
Many Thanks,
Shally
Message was edited by: testing34 -
Server Push Intermittent message loss
We are using LCDS 2.6 and using the RTMP port for the server push. However, at times the notifications in between the server to clients goes missing. It works pretty good at times and after some time, it does not shows notification.
We are using DataTransactionServices for pushing the data from LCDS to the Flex clients.Hello,
We are still facing the intermittent issue with LCDS. Following steps has been done:
1. We tried different values in DataDestination property like autoSyncEnbaled , cache items and some other properties, but it did not work.
2. We analysed LCDS logs in log file and found that :
a. Java Code is pushing updated state to LCDS and message is also routing to client.
b. At client side UI is receiving old data from LCDS.
Do you have any idea, why is this happening?
Gaurav Shukla
Senior Technical Architect -ADCOE
HCL Technologies Ltd.
SEZ, Plot No. 3A, Sector 126, Noida 201301, U.P. (India)
Mob: +91-9899 89 9189
www.hcltech.com<http://www.hcltech.com>
www.hcl.com<http://www.hcl.com>
cid:[email protected] -
Server push with Javamail: idle() blocks
Hi,
today I tried to implement server push functionality in my mail application via Javamail.
I did this by calling the following method everytime Javamail creates a new Folder instance for me:
private void activateServerPush(Folder f) {
if (f instanceof IMAPFolder) {
final IMAPFolder ifo = (IMAPFolder) f;
ifo.addMessageCountListener(new MessageCountListener() {
@Override
public void messagesAdded(MessageCountEvent arg0) {
DebugPrinter.print(this, "messagesAdded event called");
clear(false, true); // Clear cache
onMessageCountChanged();
@Override
public void messagesRemoved(MessageCountEvent arg0) {
DebugPrinter.print(this, "messagesRemoved event called");
clear(false, true); // Clear cache
onMessageCountChanged();
MyThread thread = new MyThread() {
@Override
public void run() {
while (true) {
DebugPrinter.print(this, "Before idle");
try {
ifo.idle();
DebugPrinter.print(this, "After idle");
} catch (MessagingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
DebugPrinter.print(this, "After idle try");
// Start thread
ServletThread.EXECUTOR_SERVICE.submit(thread);
}Now, when I run the code above, I only get "Before idle" as output.
The rest won't be printed so it seems like idle() is blocking.
Also, the event listener messagesAdded(...) are not called. I tried this by sending an email to myself but nothing happens.
What's wrong?Hi Bill and thanks for your reply.
How does the idle command (line) look line in the debug output?
I simply did a full text search for the word "idle" (ignore case) of everything that got printed to console and only found this:
DEBUG: mail.imap.minidletime: 10
* CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT IDLE CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS AUTH=PLAIN AUTH=LOGIN
A2 OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT IDLE CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS] Logged in
Also, I noticed that the line "Before idle" (See source code in my initial posting here) gets printed but AFTER that line I can't find anything else that could refer to the idle command.
When I leave Apple Mail (my default native email client on my computer) open, the email that I sent gets correctly (instantly) pushed. -
*** [23000][2627][Microsoft][SQL Server Native Client 11.0][SQL Server]Violation of UNIQUE KEY constraint 'ClientPushMachine_G_AK'. Cannot insert duplicate key in object 'dbo.ClientPushMachine_G'. The duplicate key value is (16777412). : sp_CP_CheckNewAssignedMachine
CCCRT::RunSQLStoredProc - Failed to execute SQL cmd exec [sp_CP_CheckNewAssignedMachine] N'xxx', 1
CCRQueueRequest::GetRequestFromQueue - Failed to execute SQL cmd sp_CP_CheckNewAssignedMachine
I get the above issue and the one below at a client site; the error started with the error below then changed to the one reported above and back to the one below. Everything is working as it should but the issues
started when one of the admins at the data-centre incorrectly applied a gpo which affected a number of service accounts (sccm inclusive) and they expired....hence reporting in sccm got broke as well as this error in the ccm.log file appeared.
Remote client install still works but I believe this error affects new client discovered by sccm, so in other words devices discovered by sccm do not get the client installed automatically....but if all access and permissions are in place...pushing out the
client to the new discovered system works, it just not done automatically, which kinda defeats one the reasons for using sccm.
I have searched the breadth of the tinternet and I can only find two technet reference to the same error - one says to edit the stored procedure on the sql server which I don't think should be done... Like Jason said and I concur....its bad joo joos.
The second suggestion, said you should select all the options in the Client Push Installation properties, I have tried this but hasn't solved the problem.
I am planning to upgrade the site to the R2 CU3 before the end of the year but I would like to resolve this error before the upgrade.
The site is currently sccm 2012 sp1
Any idea?> Resolution? sil vous plait!
MerciHi ,
Please back up the database of the SCCM site. Then run the following query against the Site DB and see how it goes.
DELETE FROM System_SMS_Resident_ARR
WHERE ItemKey IN (
SELECT ItemKey FROM vSystem_SMS_Resident_ARR
GROUP BY ItemKey
HAVING COUNT(ItemKey) > 1
Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. -
Database Update and Client Pull
HI,
I want to develop a functionality in which whenever a data changes in the database table then i want to refresh the jsp page that displays the information.
Is there any easy way apart from using a client pull with a fixed interval limit? Something like a database trigger could be trapped and that information sent to the server??
Any opinions? A sample working code would be highly appreciated.
Thanks
AnuIf you already know SQL, writing your own JDBC driver that will create and access XML documents is easy
by John B. O'Donahue
As Java programmers, we have probably all used JDBC drivers. But until I received a project that was shipped without the commercial database it was built around, I had never thought of writing my own JDBC driver.
A major factor in my decision to attempt writing my own driver was that I was creating XML documents from my database tables anyway. It made sense to use the XML documents as my storage medium, and either replace the entire interface with a DOM interface, or write a JDBC driver to interface to the XML. Well, I hate ripping out code that works, and writing a JDBC driver looked like a lot of fun, so the decision was easy.
The main limitation of XML parsers is that they address the mechanics of the document, although the user is generally much more interested in content. The JDBC API, on the other hand, is geared toward handling data. A marriage of the two can give you the best of both worlds, particularly when you consider that a huge percentage of the XML on the Web was generated automatically from a database in the first place.
In this article, we'll be using the moreover.com news feeds as a real-world example of a practical use of XML. This example also shows off the advantages of a SQL-based approach. We really just want to scan for stories that interest the user, in much the same way as we scan newspaper headlines. A SQL query for headlines containing specific topics is a much more natural, content-oriented approach than a tree-parsing model, which is essentially document oriented.
http://www.devx.com/premier/mgznarch/Javapro/2001/01dec01/jo0112/jo0112-1.asp
====================
A read-only JDBC driver for Java that uses Comma Separated Value (CSV) files as database tables. Ideal for writing data import programs and conversion program.
http://sourceforge.net/projects/csvjdbc/
http://csvjdbc.sourceforge.net/
====================
http://www.amazon.com/exec/obidos/ASIN/1576101592/qid=1002215191/sr=1-10/ref=sr_1_7_10/107-9140627-3143754 -
Hi
I have a SCCM 2012 RTM installed in my network and before it was working fine and successfully installed clients by Client push method
Now I added another forest and successfully discovered all computers in the second forest able push client and successfully installed
Now my problem is , all client computer's in the first forest activity showing "active" and recieves updates from server without any issue. But I could not push the client installation to new computers on the first forest (active directory). While
monitor the ccmsetup.log file on each new computer the installation get stuck on BITS download
I am not saying , this is server configuration problem because when I push the client installation to the computers on second forest, the package downloaded successfully and client and SCEP installed successfully
I checked and double checked the boundary settings and DP and it was exactly same as the second boundary
I removed the boundary, boundary group and site system for the problematic computers and recreated everything as it is
But no luck still I am recieving the same status on the ccmsetup.log
please help me because I have been playing with this issue for the last one weekDear Mr Jason,
I have prepared a new laptop with windows 7 and SP1 and joined to domain
In sccm server manually run the AD system Discovery and after a while the new computer appeared on the corresponding collection
I initiated the client pushing on 6.00 PM evening and leave the laptop online (turned off computer sleep settings)
Today morning when I checked only 4 files in c:\Windows\ccmsetup folder and I checked the log.
Later I ran the same command
\\SCCMSERVER\XXX_Package\Client\ccmsetup.exe SMSSITECODE=XXX
SMSSLP=SCCMSERVER
Then
client and SCEP installed successfully within 20 minutes
How
can I find which policy or which settings block the client pushing? Do I need to check any other log file in server ?
Thanks -
Which tech can replace applet to implement server push model
We have implemented server push real-time datas to client with Applet+JSObject. but there is a thing we can not do well. When some users have intalled jre not same with our default, the applet run fail. So we are finding another tech to implement server push model.
Any suggestions!
client polling to emulate server push is cancelled.
Thanks very much!linuxhippy wrote:
well you can do it with polling - i have implemented such a system and it works very well.how many clients do your system support ?
polling period ?
what third-party libs ? -
WSUS server and client configuration issues
I just inherited WSUS from my predecessor (it was turned off because of a full disk) so I’m still learning how to use it. Turning it back on I changed where updates should come from, they were stored locally and now I’m pulling them down off of the Microsoft
Update location. What I’m seeing is that I have a bunch of computers that WSUS “sees” but are showing “Failed or Needed” status. Unless I visit each machine and manually do the updates this status does not change. Additionally I have some client computers
(Windows 7) that are not showing up as managed by WSUS. If I reading this right I’m running version Update Services 6.2.9200.16384 on Management Console 3.0 Version 6.2 (build 9200) on Windows Server 2012.
How can I force WSUS to automatically update the “Failed and Needed” devices?
How can I get those clients that are not being managed by WSUS to be managed?
Some of the things that I have done so far on the server and clients are:
Create a GPO (see attached for WSUS)
wuauclt
/detectnow
wuauclt /reportnow
wuauclt.exe /detectnow
gpupdate /force after
modifying the GPO
I even ran the SolarWinds WSUS diagnostic (as a non-administrator) and got this as the output:
# Solarwinds® Diagnostic Tool for the WSUS Agent # 1/23/2015
Machine state
User rights: User does not have administrative rights (Administrator rights are not available)
Update service status: Running
Background Intelligent Transfer service status:
Running
OS Version: Windows 8.1 Pro
Windows update agent version: 7.9.9600.17489 (WU Agent is OK)
Windows Update Agent configuration settings
Automatic Update: Enabled
Options: Automatically download and notify of installation
Use WSUS Server: Not found (There is no such key)
Windows Update Server: Not found (There is no such key)
Windows Update Status Server: Not found (There is no such key)
WSUS URLs are identical: Values are empty
WSUS Server Connectivity -- Connectivity check is impossible
So, my questions are:
What tool do I use to configure the client machine?
How do I get WSUS to update my clients?
Thanks
SamSteven,
I'm pretty sure that this is not the right forum to discuss this in but just so we can close this case.
On my computer I ran the command gpupdate /force I
then rebooted my computer to make sure that the group policy would be updated. The first screen shot is from my domain controller and the second is from my computer. As you can see the Domain Controller has the correct settings but the local machine doesn't.
Other parts of the DC GPO settings have worked so I'm somewhat comfortable that it is being propagated properly.
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