I am working on a c++/cli program that which records live video (I use OpenCV). Now I need to facilitate it with broadcast support where other people can watch it by using their web browser. As you know videos are sequence of images so I need the web page to get the new "frame" grabbed from the web cam and display it in web page in speed of 5 times in every 1 second (5fps). For this, in order to allow others to access the web page, I need a web server (running in localhost is OK because connected machines can access it).
I am not up to web technologies so I have only used Apache Tomcat and Microsoft default server.But in both, you have to setup the server, upload the files to it and much more. But there are some programs like this and this where they do not require such servers where you need to install and setup but still does the job. I think they are using embedded web servers.
So, are there are any servers like that which matches to my requirements? Please note my program is in c++/cli and I need to distribute the server with it as well, just like the above 2 programs do.
Edit
Please note that I mentioned C++ / CLI just to give you a clear understanding about my system and not because I am seeking for a server with CGI script support or I m seeking for a server built with c++. If at least JavaScript can run there that is enough because I can update using it.
Related
I need the VPS services for hosting my ASP.NET project.
However, it's not just asp.net hosting, I also need SQL Server, RabbitMq and either my running conrole app or my windows service.
So I read the suggestions to use Amazon Web Services as they provide first year for free.
However when I registered I found that I don't have a clue of where I am:
I don't see the option of creating a virtual machine with Windows
I don't see the option of setting up SQL Server on such the machine
and so on.
So I was wondering whether I'm in the right place?
Please advise if AWS can provide me with what I need or I came to the wrong place?
AWS can provide all that you listed, but you'll need to do some learning on your end.
Basically you create an EC2 instance, and then use RDP to remote into it, and you can install software and configure it to your hearts content - just like it was any other physical server.
If you want to use SQL Server, you'll have the choice of installing it directly on the instance using your own license, or using their 'hosted' version of SQL Server call RDS. You'll need to read about it and decide which option is better for your project - there is no single right way.
Lastly, I will point out that although the 'free-tier' is nice, except for a really small application (i.e. small db on a low traffic website), you may find out the 'free-tier' does not quite give you all the power you need to run a busy application. I would not base your decision on wether or not you should use AWS on how much 'free' stuff you can get. The free-tier is nice for learning, but plan on spending some money for a truly robust solution.
I have a Raspberry PI that is tightly coupled with a device that I want to control.
The desired setup I want to have would look something like this:
The physical device with interactive hardware controls on the device (speaker, mic, buttons)
A Raspberry PI coupled to the device
On the PI:
A daemon app that reacts to changes from the hardware
A Webinterface that shows the current state of the device and allows to configure the device
The system should somehow be able to update itself with new software when it becomes available (apg-get or some other mechnism).
For the Webinterface I am going to use a rails app, which is not a problem as such. What is not clear to me is the event-driven software that is talking to the hardware through gpio. Firstly, I would prefer to do this using ruby, so that I don't have a big technology gap when developing the solution.
How can I ensure that both apps start up and run in the background when the raspberry PI starts
How do I notify the webapp of an event (e.g. a button was pressed).
I wonder if it makes sense that the two pieces of software have a shared database to communicate.
How to best setup some auto-update-mechanism for both pieces of software without requiring the user to take any actions.
Apps
This will be dependent on the operating system
If you install a lightweight version of Linux, you might be able to create some runtime applications or something. I've never done anything like this; but I know from Windows you can create startup programs -- likewise, you should be able to do something similar in Linux
BTW you wouldn't "run" the Rails app - you'll fire up the server to capture any requests. You'd basically run your app locally in "production" mode - allowing you to send requests, either through localhost, or setup a pseudo domain in the HOSTS file of your box
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Web App
The web app itself is RESTful, meaning (I believe), it will only act upon having requests sent to it. Because this works over the HTTP protocol, it essentially means you'll need some sort of (web) service to send requests to the web app:
Representational state transfer (REST) is a way to create, read,
update or delete information on a server using simple HTTP calls
Although I've never done this myself, I would use the ruby app on your PI to send HTTP requests to your Rails app. This will certainly add a level of complexity, but will ensure you an interface the two types of data-transfer
The difference you have is Rails / any other web app will only act on request. "Native" applications will run as long as the operating system is operating; meaning you can "listen" for updates from the hardware etc.
What I would do is split the functionality:
Hardware input > send to service
Service > sends to Rails
Rails > sends response to service
Service > processes response
This may seem inefficient, but I think it's the best way to capture local-based input from your hardware. You'll have to use a localhost rails app, running with something like nginx or some other efficient server
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Database
it would only make sense if they shared the data. You should remember that a database is different than a datatable. A database stores many tables, and is generally meant for a single purpose; whilst a datatable stores a single type of data.
From what you've written, I would recommend using two databases running on the same db server. This will give you the ability to create as many tables as you want for these databases - giving you scope to add as many different pieces of data you wish to each. Sharing data can be done using an API or a web service
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Updating
Rails app will not need to be "updated" - you'll just need to deploy a fresh version. The beauty of Internet-centric software :)
In terms of your Rasberry-PI "on-board" software update - I don't have much experience with this, so can only recommend
I'm planning on writing a control panel for Minecraft in Rails but I don't have much experience with Java at all, Minecraft seems to have some standard remote connection and query tools, but most conventional panels don't seem to use them. For example with McMyAdmin, I have disabled remote connectiona and the query, but it still seems to be able to communicate with the server after restarting it after I've edited the server configs to disable the settings.
What I'm asking is if anyone knows how McMyAdmin communicates with the Minecraft server, it comes with a plugin, but I've deleted that as well and it still seems to be able to communicate with the server, I know McMyAdmin is written in .NET and I believe it uses Mono as it's server, as it's cross platform.
If anybody could shed some light on this I'd be ever so greatful, just trying to get my head around the communication.
McMyAdmin uses the plugin to open a socket that it can interact with(Not sure which features are provided using this plugin). The rest of the features are just from the Process instance that it creates. It also just edits the config files for a few things as well or runs commands using the input stream of the process.
I'm a hobby programmer trying to build a client/server application suite, using Delphi XE.
I write stand-alone applications occasionally, for my personal use. The problem is I don't know ANYTHING when it comes to networking / multi-tier. I am willing to learn though.
I looked for ways to do this and DataSnap and IntraWeb jump out as the most likely candidates for the job. But, before I start using one or the other, I would like to know a few info I wasn't able to find on the web:
If I build an IW stand-alone app and deploy it on my site (as server) will I be able to connect to it/retrieve data with a client application? I need to do that within my Delphi written app, without using a browser and without using HTML (I know very little HTML and I'm not eager to learn). I know IntraWeb isn't meant for this, but will it work?
If I go with DataSnap and build a server app, will I be able to deploy it to my website? Or do I have to make a computer on the network the server?
In case anyone wants to know, I want to connect 5 computers(from different cities), to exchange information between them, if at all possible using ADO, as I'm very familiar with it.
Intraweb is a server based tool for building web sites, accessed via a browser. It is not "proper" multi-tier, and it sounds like it isn't what you need.
DataSnap is designed to do what you want I think. First, the ADO part would be on the server, and you would define an interface that the server offers to do tasks. Then your clients would call that interface over the internet to get data or do those tasks etc.
As for whether they will work on your web server, that depends on what your server is, and the access that is provided to it. A web server is just a PC, but typical hosting is fairly restricted to running "scripted" languages on that server, which reside in the hosting directory. A Delphi server would be a running executable (usually a Windows Service), listening on a port, and needs much more access to the computer than typical. You would need at least a virtual Windows server with administrator access to the desktop to allow it to work. In the first instance though, you could happily run the server on a DSL line or similar and make it work just fine. You can worry about hosting it on the net when you have customers paying for it.
The situation is simple. I've created a complex Delphi application which uses several different techniques. The main application is a WIN32 module but a few parts are developed as .NET assemblies. It also communicates with a web service or retrieves data from a specific website. It keeps most of it's user-data inside an MS Access database with some additional settings inside the Registry. In-memory, all data is converted inside an XML document, which is occasionally saved to disk as backup in case the system crashes. (Thus allowing the user to recover his data.) There's also some data in XML files for read-only purposes. The application also executes other applications and wants for those to finish. All in al, it's a pretty complex application.
We don't support Citrix with this application, although a few users do use this application on a Citrix server. (Basically, it allows those users to be more mobile.) But even though we keep telling them that we don't support Citrix, those customers are trying to push us to help them with some occasional problems that they tend to have.
The main problem seems to be an occasional random exception that seems to pop up on Citrix systems. Never at the same location and often it looks related to some memory problems. We've p[lenty of error reports already and there are just too many different errors. So I know solving all those will be complex.
So I would like to go a bit more generic and just want to know about the possible issues a Delphi (2007) can have when it's run on a Citrix system. Especially when this application is not designed to be Citrix-aware in any way. We don't want to support Citrix officially but it would be nice if we can help those customers. Not that they're going to pay us more, but still...
So does anyone know some common issues a Delphi application can have on a Citrix system?
Does anyone know about common issues with Citrix in general?
Is there some Silver Bullet or Golden Hammer solution somewhere for Citrix problems?
Btw. My knowledge about Citrix is limited to this Wikipedia entry and this website... And a bit I've Googled...
There were some issues in the past with Published Delphi Applications on Citrix having no icon in the taskbar. I think this was resolved by the MainFormOnTaskbar (available in D2007 and higher). Apart from that there's not much difference between Terminal Server and Citrix (from the Application's perspective), the most important things you need to account for are:
Users are NEVER administrator on a Terminal or Citrix Server, so they no rights in the Local Machine part of the registry, the C drive, Program Folder and so on.
It must be possible for multiple users on the same system to start your application concurrently.
Certain folders such as the Windows folder are redirected to prevent possible application issues, this is also means that API's like GetWindowsFolder do not return the real windows folder but the redirected one. Note that this behaviour can be disabled by setting a particular flag in the PE header (see delphi-and-terminal-server-aware).
Sometimes multiple servers are used in a farm which means your application can run on any of these servers, the user is redirected to the least busy server at login (load balancing). Thefore do not use any local database to store things.
If you use an external database or middleware or application server note that multiple users will connect with the same computername and ip address (certain Citrix versions can use Virtual IP addresses to address this).
Many of our customers use our Delphi applications on Citrix. Generally speaking, it works fine. We had printing problems with older versions of Delphi, but this was fixed in a more recent version of Delphi (certainly more recent than Delphi 2007). However, because you are now running under terminal services, there are certain things which will not work, with or without Citrix. For example, you cannot make a local connection to older versions of InterBase, which use a named pipe without the GLOBAL modifier. Using DoubleBuffered would also be a really bad idea. And so on. My suggestion is to look for advice concerning Win32 apps and Terminal Services, rather than looking for advice on Delphi and Citrix in particular. The one issue which is particular to Citrix that I'm aware of is that you can't count on having a C drive available. Hopefully you haven't hard-coded any drive letters into your code, but if you have you can get in trouble.
Generally speaking, your application needs to be compatible with MS Terminal Services in order to work with XenApp. My understanding is that .NET applications are Terminal Services-compatible, and so by extension should also work in a Citrix environment. Obviously, as you're suffering some problems, it's not quite that simple, however.
There's a testing and verification kit available from http://community.citrix.com/citrixready that you may find helpful. I would imagine the Test Kit and Virtual Lab tools will be of most use to you. The kit is free to use, but requires sign-up.
Security can be an issue. If sensitive folders are not "sandboxed" (See Remko's discussion about redirection), the user can break out of your app and run things that they shouldn't. You should probe your app to see what happens when they "shell out" of your app. Common attack points are CHM Help, any content that uses IE to display HTML, and File Open/Save dialogs.
ex: If you show .chm help, the user can right-click within a help topic, View Source. That typically opens Notepad. From there, they can navigate the directory structure. If they are not properly contained, they may be able to do some mischief.
ex: If they normally don't have a way to run Internet Explorer, and your app has a clickable URL in the about box or a "visit our web site" in the Help menu, voila! they have access to the web browser. If unrestrained, they can open a command shell by navigating to the windows directory.