How would I implement a system that will keep 20 applications running on a closed network to stay synchronized whilst performing various tasks?
Each application will be identical, on an identical machine. These machines will have a socket connection to the master application that will issue TCP commands to the units such as Play:"Video1.mp4". It is vital that these videos are played at the same time and keep time with each other.
The only difference between each unit is that the window will be offset on the desktop, so that each one has a different view port on the application - as this will be used in a multi-projector set up.
any solutions/ideas would be greatly appreciated.
I did it some years ago. 5 computers running 5 instances of the same flash app. Evey app was displaying a "slice" of the same huge app and everything needed to be synchronized at fractions of seconds precision.
I used a simple Python script (running on a 6th machine) that was sending OSC messages on the local network. the flash apps were listening through FLOSC to this packets, and were sending to the Python script message about their status.
The stuff was running at the Withney Museum (NY) and at Palais de Tokyo (Paris), so I'm quite confident about the solution :) I hope it helps you
You have to keep tracking and latest updated data in your master application. you have to broadcast your newly updated data to all connected client to deliver updated data. after any update from any client you have to send updated data to all connected clients.
In FMS remote shared object is used to maintain data centrally across the network connected application via FMS. when any client is sending any updated OnSync Event is fired to all client application and data is sync with FMS Remote Shared Object. So this kind of Flow you have to develop for proper synchronization of data across network.
you can also use the RPC system to sync data between all connected application to the Master application. in that you have to init RPC to the client to Master application to send data update and Master application send RPC to all other client which are connected to the Master application.
Related
We'd like our PHP based environment to auto scale up and down based on load.
Our users send emails that get queued in postfix queues on the machine, and we also have other short running tasks in the background (e.g. creating PDFs).
Is there any way we can tell the scaling thing to wait until the mail spool is empty and any currently running jobs have finished?
I'd rather stay away from worker environments for now to make migrating to AWS easier/more similar to our existing setup.
Thanks in advance.
how to prevent automatic repeat http request from client machine to tomcat server?
i have a problem in my live web applicaton working through local LAN.when a network failure occur sometimes multiple insertion take place in my mysql data base.
Any one know about these type of issues?
my application use tomcat as web sever and centos as interface
I have a spark 1.2.1 cluster set up in standalone mode with a master and a few slaves. I then let my data scientists enjoy the cluster's power.
All is working fine. However, the dedicated server that my data scientists used to submit spark jobs have its spark.local.dir filled up gradually.
Given that this machine is sitting outside of the cluster, not a master, nor a worker/slave, I wouldn't think that the local spark.local.dir is used in any way by spark. (And why would it? It only shows the logs.)
I could not find a good doc detailing this part of information. Does anybody have an idea?
Not enough information about your setup to be sure, but I am guessing that the jobs are launched in client mode where the driver would be on your client node.
From the spark docs:
In client mode, the driver is launched in the same process as the client that submits the application. In cluster mode, however, the driver is launched from one of the Worker processes inside the cluster, and the client process exits as soon as it fulfills its responsibility of submitting the application without waiting for the application to finish.
I am guessing that in client mode the driver (on your client machine) of the application needs plenty of scratch space to manage the other workers in that case.
My company has Desktop application developed in vb.net using devexpress controls. Back End database is MySQL.
Company is in retailing and have 2 retail stores in in same city. Both stores always stay busy and customers are always in waiting at the counter. Basically, it is desktop based CRM application which has lot of modules inside it apart from invoice/Receipt module, it has other modules like Delivery module, installation module, Service/Repair module, Account Receivable module and many other modules used by various back office departments of the company. Other resources/hardware such as Barcode Printer, Receipt Printer, and Barcode scanner are connected to the CRM on Desktop PC.
Currently, there are around 55 clients always connected to server and using application.
Problem:
Till couple of weeks back, company had no issue using this desktop application and single MySQL server as all clients were connected via LAN or WLAN.
Now situation has changed, and new requirement has raised: Company has planned to open new stores at very far distance. Such stores cannot be connected to current central database via LAN or WLAN. Each new branch would have around 20-30 clients, say “Branch Clients”
Also, there would be field executive who will be working from their laptop. Say “Remote Clients”. They will just have 3G internet connection on their laptop.
Thought 1: Install desktop application at all branch PCs, and connect them to central MySQL database server over the internet.
Not possible: Connection over the internet would be very slow for fetching such huge data. Data is really huge For, e.g. if client opens “Customer Master”, then there would be more than 600,000 rows which takes lot of bandwidth and time to open over the internet. And there are many more such modules which loads lot of data.
Also, in case of losing internet connection, clients would not able to operate the application. Customer waiting in line to make receipt would go crazy if they have to wait for long.
Thought 2: Install new MySQL server at branch store, all the desktop PCs then would be connected to that local branch server. And then that local branch server would be connected to central server via MySQL replication option.
Not possible: Since MySQL replication has limitation of only one way replication, we cannot implement this structure. Application requires to move data from central server to branch server and from Branch to Central in real-time. Also, MySQL replication engineering has limitation to replicate only with one server only. In that case, we cannot replicate with multiple branch stores. There is an option of cluster server, but company cannot afford licensing cost.
Thought 3: Somebody suggested me that I should transfer entire desktop application into Web Application and get cloud server for database.
Not possible: I think looking at current requirement (fast access), environment (retail store-pos) and hardware (printers, scanners) connected to client - it is not advisable to have web application and cloud database server. Also in the event of no internet, entire store would go down.
Thought 4: Somebody suggested me that I should move from MySQL server to MSSQL and keep desktop application as it is. MSSQL has capability to sync with multiple servers in real-time over the internet. It has no limitation like MySQL’s one way replication and only one replication connection.
I guess, to make faster and constant database connection, installing local branch server is highly required. But I don’t know how those different branch servers could be connected to central server.
My Questions:
• What is the best way to resolve above issues in given condition and successfully fulfill the company’s requirement? Faster and constant connection to database server. And also real-time updates between all branches and central server. If internet connection is down, then delay in real-time update is acceptable but clients should not be affected from work.
• Would migration from MySQL to MSSQL resolve the issue? Because data migration is not issue as there are many tools available which converts the database from one platform to other. But issue is - application is very huge having hundreds of query written for MySQL. I guess I have to change those all queries also, because queries are not same for MySQL and MSSQL. Do I have to change all the queries or just the few percentage queries? Or if there is any tool available which convert queries from MySQL to MSSQL query.
• In general, how such small-medium retail store company have their infrastructure and application setup? Let me know some ideas.
I am using phonegap to make iphone and android apps. I need to be able to store data on a mysql database on my server as well as use my websocket server.
How can I go about doing this as the app will be running on local html and javascript files which cant run ajax/websocket requests on external servers?
So let me convert my comments into an answer.
You need a client-server architecture, where the clients will be all your end devices. The server in this case needs to be a globally reachable host somewhere (Amazon cloud, perhaps?).
Your device will send updates to the backend server that has a connection to your database, using ajax calls. These updates will be stored on the server.
All your other clients need to periodically poll the same backend server using ajax, and will get the updates sent from your primary device.