I am familiar with the Concept of amazon SWF . I can see many SDK in different languages to use SWF services. Also, amazon Flow Framework is a set of library to implement distributed applications . Currently this Flow Framework is available in Java and Ruby . Then how can we write distributed applications using SWF in other languages like python , php etc. Does this mean amazon provides the framework in Java and Ruby only , rest of the languages have other vendor's libraries ? Please explain .
You are right that AWS currently only provides high-level frameworks for Ruby and Java ("Flow" frameworks). Low-level access to SWF is available in most (all?) official SDKs though: boto2/3 for Python, go-sdk, etc.
When using SWF, you'll find yourself implementing mainly two types of programs: "activity workers" and "deciders" (http://docs.aws.amazon.com/amazonswf/latest/developerguide/swf-dev-actors.html).
Using the Flow framework is not mandatory, but it helps implementing deciders by providing high-level abstractions for describing synchronisation points, defining which tasks can be run in parallel, retries, etc. There are also non-official libraries (I'm personally maintaining one for my company, "simpleflow").
If you want to use other languages for deciders, I recommend you try to use an existing framework first, then see if you want to implement this yourself (it's not trivial from my experience).
If you want to implement activities in other languages, I recommend you start using the Flow framework end-to-end, and then you can either 1/ fork and use your favorite language as a subprocess of Ruby/Java Flow workers, or 2/ mimic the serialisation logic of the Flow framework and implement workers directly yourself with low-level APIs (which is simple: poll for an activity, do work, then respond to SWF with the result).
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I have written a UI in Electron and I would like to connect it with my C++ code. However, I will be selling this product and so I would like to know if this makes it easier for people to crack my C++ code? Obviously I know compiled C++ can be cracked anyway, but does this affect it in any way?
Additionally, what is the best way to go about this while preserving maximum possible security?
Thanks.
EDIT: How about this? Is it possible to use c++ as back-end for Electron.js?
EDIT2: To clarify, my Electron app will be showing the status of operations being performed in the C++ program. As such, I will need to send lists, dictionaries, strings etc. from C++ to JS which will then render it. Additionally, buttons on my Electron app need to trigger actions in the C++ code, such as stopping or starting certain parts of the program.
I have written a UI in Electron and I would like to connect it with my C++ code ...
I would like to know if this makes it easier for people to crack my C++ code?
Using electron does not make any meaningful difference for protecting the C++ source code. (Your intellectual property)
The Javascript code running in electron will be very easy to reverse engineer though, which gives users a head start on experimenting with your C++ binary. Using minification and obfuscation tools can at least make that harder.
For the C++ side, connecting C++ to Electron can be done in at least these two ways:
By dynamically linking to a shared library (Node.js C++ Addons)
In this case your C++ API would be functions that get exported by the shared library. There are many tools to inspect shared libraries (DLLs) and view these functions.
By communicating with another process using some sort of Inter-process communication.
In this case your API would depend on the IPC method used. If it was TCP/UDP messages you could use Wireshark to inspect the packets between the processes. There are ways to inspect messages going over any type of IPC.
Either way, your application must be delivered to the end-user with a compiled binary. Preventing reverse engineering of the binary itself is impossible if you actually give the binary to your users.
You should also expect that a savvy end-user will have access to other tools that can inspect the API and implement third-party code that talks to that API.
Additionally, what is the best way to go about this while preserving maximum possible security?
By "maximum possible security", I will assume you are referring to preventing unauthorized use of the C++ code with other applications.
You would need a licensing system that can authenticate the application that is using your C++ binary's API. Explaining what that would be exactly is probably too large of an answer for a Stack Overflow, and you will have to do some research on how licensing systems are implemented.
It may be theoretically impossible to develop a perfect licensing system though. Look at the gaming industry, it takes just a matter of days to for the licensing software become circumvented for every new game that is released. The only software architecture that cracks haven't completely conquered are cloud-based applications, which don't actually deliver compiled code with their business logic to the end-user's computer.
How does AppDynamics and similar problems retrieve data from apps ? I read somewhere here on SO that it is based on bytecode injection, but is there some official or reliable source to this information ?
Data retrieval by APM tools is done in several ways, each one with its pros and cons
Bytecode injection (for both Java and .NET) is one technique, which is somewhat intrusive but allows you to get data from places the application owner (or even 3rd party frameworks) did not intend to allow.
Native function interception is similar to bytecode injection, but allows you to intercept unmanaged code
Application plugins - some applications (e.g. Apache, IIS) give access to monitoring and application information via a well-documented APIs and plugin architecture
Network sniffing allows you to see all the communication to/from the monitored machine
OS specific un/documented APIs - just like application plugins, but for the Windows/*nix
Disclaimer : I work for Correlsense, provider of APM software SharePath, which uses all of the above methods to give you complete end-to-end transaction visibility.
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I want some examples. I always get confused, so with some examples I might be able to figure it out better.
Also: Is Eclipse an API or IDE?
An IDE is an integrated development environment - a suped-up text editor with additional support for developing (such as forms designers, resource editors, etc), compiling and debugging applications. e.g Eclipse, Visual Studio.
A Library is a chunk of code that you can call from your own code, to help you do things more quickly/easily. For example, a Bitmap Processing library will provide facilities for loading and manipulating bitmap images, saving you having to write all that code for yourself. Typically a library will only offer one area of functionality (processing images or operating on zip files)
An API (application programming interface) is a term meaning the functions/methods in a library that you can call to ask it to do things for you - the interface to the library.
An SDK (software development kit) is a library or group of libraries (often with extra tool applications, data files and sample code) that aid you in developing code that uses a particular system (e.g. extension code for using features of an operating system (Windows SDK), drawing 3D graphics via a particular system (DirectX SDK), writing add-ins to extend other applications (Office SDK), or writing code to make a device like an Arduino or a mobile phone do what you want). An SDK will still usually have a single focus.
A toolkit is like an SDK - it's a group of tools (and often code libraries) that you can use to make it easier to access a device or system... Though perhaps with more focus on providing tools and applications than on just code libraries.
A framework is a big library or group of libraries that provides many services (rather than perhaps only one focussed ability as most libraries/SDKs do). For example, .NET provides an application framework - it makes it easier to use most (if not all) of the disparate services you need (e.g. Windows, graphics, printing, communications, etc) to write a vast range of applications - so one "library" provides support for pretty much everything you need to do. Often a framework supplies a complete base on which you build your own code, rather than you building an application that consumes library code to do parts of its work.
There are of course many examples in the wild that won't exactly match these descriptions though.
The Car Analogy
IDE: The MS Office of Programming. It's where you type your code, plus some added features to make you a happier programmer. (e.g. Eclipse, Netbeans). Car body: It's what you really touch, see and work on.
Library: A library is a collection of functions, often grouped into multiple program files, but packaged into a single archive file. This contains programs created by other folks, so that you don't have to reinvent the wheel. (e.g. junit.jar, log4j.jar). A library generally has a key role, but does all of its work behind the scenes, it doesn't have a GUI. Car's engine.
API: The library publisher's documentation. This is how you should use my library. (e.g. log4j API, junit API). Car's user manual - yes, cars do come with one too!
Kits
What is a kit? It's a collection of many related items that work together to provide a specific service. When someone says medicine kit, you get everything you need for an emergency: plasters, aspirin, gauze and antiseptic, etc.
SDK: McDonald's Happy Meal. You have everything you need (and don't need) boxed neatly: main course, drink, dessert and a bonus toy. An SDK is a bunch of different software components assembled into a package, such that they're "ready-for-action" right out of the box. It often includes multiple libraries and can, but may not necessarily include plugins, API documentation, even an IDE itself. (e.g. iOS Development Kit).
Toolkit: GUI. GUI. GUI. When you hear 'toolkit' in a programming context, it will often refer to a set of libraries intended for GUI development. Since toolkits are UI-centric, they often come with plugins (or standalone IDE's) that provide screen-painting utilities. (e.g. GWT)
Framework: While not the prevalent notion, a framework can be viewed as a kit. It also has a library (or a collection of libraries that work together) that provides a specific coding structure & pattern (thus the word, framework). (e.g. Spring Framework)
Consider Android Development:
IDE: Eclipse etc..
Library: android.app.Activity library (Class with all code)
API: Interface basically all functions with which we call
SDK: The Android SDK provides you the API libraries and developer tools necessary to build, test, and debug apps for Android
(----tools - DDMS,Emulator ----platforms - Android OS versions, ----platform-tools - ADB, ----API docs)
ToolKit: Could be ADT Bundle
Framework: Big library but more of architecture-oriented
In other words...
IDE
Even notepad is an IDE (not notepad.exe) - Software you write/compile code with is an IDE.
Library
A bunch of code which simplifies functions/methods for quick use.
API
A programming interface for functions/configuration which you work with, its usage is often documented.
SDK
Extras and/or for development/testing purposes.
ToolKit
Tiny apps for quick use, often GUIs.
GUI
Apps with a graphical interface, requires no knowledge of programming unlike APIs.
Framework
Bunch of APIs/huge Library/Snippets wrapped in a namespace/or encapsulated from outer scope for compact handling without conflicts with other code.
MVC
A design pattern separated in Models, Views and Controllers for huge applications. They are not dependent on each other and can be changed/improved/replaced without to take care of other code.
Example:
Car (Model) The object that is being
presented.
Example in IT: A HTML form.
Camera (View) Something that is able to see the object(car).
Example in IT: Browser that renders a website with the form.
Driver (Controller) Someone who drives that car.
Example in IT: Functions which handle form data that's being submitted.
Snippets
Small codes of only a few lines, may not be even complete but worth for a quick share.
Plug-ins
Exclusive functions for specified frameworks/APIs/libraries only.
Add-ons
Additional modules or services for specific GUIs.
SDK represents to software development kit, and IDE represents to integrated development environment. The IDE is the software or the program is used to write, compile, run, and debug such as Xcode. The SDK is the underlying engine of the IDE, includes all the platform's libraries an app needs to access. It's more basic than an IDE because it doesn't usually have graphical tools.
I'm currently starting to integrate "Delphi Web Script" in my application basically only as a scripting engine (interfacing with functions, classes, etc.); awesome software for the standard delphi open source quality in my opinion, but just for curiosity,
What's exactly the "web part" of the project?
How is intended to be used?
It was used somewhere with some success commercially?
Thanks!
As ain said, the original use was for PHP-like, ASP-like server-side web-page generation, but it was also capable of general purpose use, which is what I used it for. And as I did not use the "web" side of DWScript, most of the "web-oriented" features haven't been ported over (only the HTML Filter was ported actually).
The Web functionality is still available in the SourceForge repository, if someone wants to tackle the port. Though, they may be outdated beyond simple renamed methods and classes, as since DWSII, the script engine has gained various features. For instance, it is now capable of multiple thread-safe executions of a single compiled script, while the old codebase is built around the limitation that a compiled script can be executed by only one thread at a time.
On the other hand, there are some new features that could simplify the porting, the simple WebServer demo recently added uses RTTI to expose TWebResponse & TWebRequest f.i. (was manually exposed in DWSII). On the down side, that's only possible with recent Delphi versions.
AFAIK the main focus of the original author of this scripting engine was to make it possible to embed Pascal scripts into HTML pages, just like ie PHP does it. Hence the name "Delphi Web Script". While the focus of the current maintainer, Eric Grange, is on using it as a general purpose scripting engine, it should still be possible to use it for web purposes as well - for that you use the "filters" feature of the library. Check out the dwsHtmlFilter unit for HTML filter.
Are there any important features in Rails or Django which do not exist in the other framework?
Is there anything important missing - for an enterprise web app - in either one?
This question is not intended to be argumentative - I am trying to make an informed technology decison for an upcoming project. Two of the concerns I have, with regard to choosing one of these frameworks, are:
Integration with external systems (Java, .Net, SAP, etc)
Reporting - would there be any difficulties producing sophisticated reports/charts (financial) using either framework. This would require multi-table joins, custom sorting, pagination (w/ajax) and printing for different devices.
Django on Jython is running nicely so Java integration shouldn't be a problem.
In terms of integration in general don't forget that Django is also Python so you have the massive support of the standard library plus all the other mature well supported Python projects out there. Integrating 3rd party Python code into Django projects is usually trivial.
At the risk of getting evangelical I would list the following Django killer features:
The admin
The documentation
Python ;-)
Django also has GeoDjango. The NY Times chose Django over Ruby for their Represent project for easy mapping support:
"We built Represent with Django, the Python web framework. Although we do most of our work with Ruby on Rails, we chose Django for this project so we could use GeoDjango, an add-on that supports geometry fields and extends the ORM to allow spatial queries."
My experience/opinion is that Rails is much more flexible and has a more diverse ecosystem and is developing faster while Django is more stable, slower changing, better documented.
Rails has a huge advantage for integration with other systems via JRuby. You can give rails access to the entire Java ecosystem and run it on the JVM.
Django might be able to take advantage of .Net via IronPython (I don't know anything about this other than that IronPython exists - while IronRuby is only on the way but not here yet)