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I have started a crash course of IndexDB API. I have heard from the author that the API is a little bit confusing. Primarily, as we have been working with the promise pattern as this API doesn’t use this pattern. Secondary, there are different wrappers, one of them seems is from Github author’s personal library so I suppose he have created it.
However looking for a different flavor, I found this one: http://dexie.org/. Also supports the Promise pattern. See http://dexie.org/docs/Promise/Promise, http://dexie.org/docs/API-Reference#query-items . It seems “promising”.
Also I found that the IndexDB 2.0 API was created post the video time. It is already being supported since beginning of 2017. From a Mozilla developer, I found since Firefox 51 (Jan 2017) it is already there. And he wrote what’s the differences among 1 and 2 versions https://hacks.mozilla.org/2016/10/whats-new-in-indexeddb-2-0/
So my question is if at this point is better to use the wrapper libraries or to use the native IndexDB API in terms of cross-browsing and support and better practices?
It all depends on what you want to do with indexeddb -
If you are learning indexeddb for your interest or for knowledge then you should go for plain indexeddb. Learn and research as much you can, because it has too many apis and you will have to write code for every type of situation.
You want to use indexeddb in your project and dont have much time to explore indexeddb. You only want to do some database operations and release your project. In this case - you should go for indexedd library. This way you dont need to worry about indexeddb code . You will just write simple code using the library.
For instance : check out this article - https://dzone.com/articles/crud-operation-in-indexeddb-using-jsstore. How a library makes indexeddb so easy.
Hope this will help you.
I am sure after WebAssembly Post-MVP, asm.js will be deprecated. Even now, a few existing asm.js projects already start to use WebAssembly. JS engine (V8) also starts to comiple asm.js to WebAssembly, so even if old projects never migrate, end-users will still get partial advantages from WebAssembly.
My question is, what about native-client then? It is not implemented in JS engine so that can be a problem. Native-client seems to be deprecated even now. Will native-client be completely removed from Chrome in foreseeable future? I would love to see some reduction in binary size of Chrome.
Side questions:
After thread/gc/simd/exception are included in WebAssembly, is there still something native-client has but missing in WebAssembly (blocking migration)?
It took WebAssembly about 2 years just to reach MVP, what is the expected time for any one of the Post-MVP to get finalized?
It seems like WebAssembly group is tackling multiple Post-MVP features at once instead of one by one, won't that make it slower to finalize one of them?
Answering the side-questions only, because I no longer work on Native Client. Google's plans are its own to speak for, so I'll make this a wiki.
Update as of 2017/05/20 NaCl isn't in glibc. This was the original libc which was supported, and took quite a while to clean up and upstream. It was only ever supported by NaCl's GCC toolchain. There's still support for musl libc, which works with the more up-to-date LLVM-based NaCl and PNaCl toolchain.
Update as of 2017/05/30 the Chromium team announced the fate of PNaCl and tentative roadmap of WebAssembly features.
Here are some Native Client features which you haven't mentioned:
Out-of-process, which many consider a bug because it forces asynchronous communication. It allows guaranteed address space, which with 64-bit isn't much of an upside, and was critical to Native Client's double-sandbox design. WebAssembly doesn't have processes yet.
Has blocking to and from the JavaScript event loop, through postMessageAndAwaitResponse. Also seen as a bug by many.
Has many APIs through Pepper. Many mirror the web platform's APIs.
Can do memory protection through mprotect (though execute pages are limited).
POSIX signals can be handled.
Supports computed goto and other irreducible control flow.
Has some Just-in-Time code patching support.
Supports weaker than seq_cst atomics.
Has support for inline assembly, as long as it follows the NaCl validation rules.
Not all of these are in Portable Native Client, though. There's official documentation of differences.
There's no timeline for any of the post-MVP WebAssembly features. We don't want to rush anything, but we want to deliver one the most useful things first. It's a community group, so priorities are really driven by whoever gets involved. Implementations won't be able to tackle features all at once, but exploration parallelizes well.
Simple question, I want to know is Java free (especially for web development). Later on if I've build a large website, will the servers, databases cost me much like in .net for example?
Cheers.
Java is free. Check licences of frameworks you're using, but you shouldn't worry about that since most of them are free.
Servers (physical) will, of course, cost you.
There are free application servers like Glassfish and JBoss.
There are free databases like mySQL and PostgreSQL.
So, you can get away with everything being free except hardware and, possibly, hosting of your web app.
Yes and no - depending on how big your site gets, you may be required to invest more money into better servers/databases.
It's not really something that can just be answered, without looking into the future.
Update, as of 2021
Be sure to read the document prepared by pillars of the Java community, Java is Still Free. This document provides a short overview as well as a longer section with all the gory details.
Understand that Java is a set of specifications, not a product.
Java Language and Virtual Machine Specifications
JEPs and JSRs
Many vendors provide binaries or installers for an implementation of Java. Nowadays, all of those implementations are based largely or entirely on the OpenJDK project. Participants including Oracle, IBM, SAP, Apple, Azul Systems, and more have banded together to pool their best technologies for implementing Java as open-source free-of-cost.
The OpenJDK project provides only source-code. Various vendors build that source code to provide binaries or installers for you and me to conveniently put Java on our computers. Some of their distributions of Java are available free-of-cost, and some are commercial with paid support. Some are general-purpose JVMs, and some are special-purpose. Some are a basic JDK and some have bundled extras.
Here is a diagram I made to help you in choosing a vendor for a Java implementation.
And some considerations to think about when choosing a vendor.
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I need some resources that talk about how to design your software to be extensible, i.e. so that other people can write add-ons/plug-ins that adds functionality to it.
What do you recommend? Any books out there that discuss the subject?
I would prefer something that's short and to the point; a bit of theory and a bunch of concrete examples.
I'm not targeting a specific language, I want to be able to understand the core idea so that I can implement it in any language.
And for the same reason, I prefer not to do it using a framework that someone else built (unless the framework is not very high-level, i.e. doesn't hide too much), at the moment I only want to educate myself on the subject and experiment with various ways to implement it. Plus, a framework usually assumes user's knowledge about the subject.
UPDATE
I'm not asking about OOP or allowing my classes to be inherited. I'm talking about designing an application that will be deployed on a system, such that it can be extended by third-party add-ons AFTER its been deployed.
For example, Notepad++ has a plug-in architecture where you can place a .dll file in the plugins folder, and it adds functionality to the application that wasn't there, such as color-picking, or snippet insertion, or many other things (a wide range of functionality).
IF we're talking .NET, try Scripting .NET applications with VBScript over on CodeProject. Lots of concrete examples there.
Below are sites implementing various application extension techniques
ClearScript - Makes V8, VBScript and JScript available to .NET apps
CS-Script - The C# Script Engine
Plugin Architecture using C#
Opinio plugin architecture
Notes on the Eclipse Plug-in Architecture
Plug-in Architecture Framework for Beginners
Gecko plugin architecture
Fungimol plugin architecture
OSGI is a good practical example of a technical framework allowing to do what you are after.
The theory is here.
The (free!) book is there.
Extensibility and the ability to write plugin must deal with service lifecycle
adding / removing service/plugin on the spot
managing dependencies between services
managing states of services (declared, installed, started, stopped,...)
What is OSGI for ?
One of the main functions of a module is as a unit of deployment… something that we can either build or download and install to extend the functionality of our application.
You will find a good introduction here, on the central notion of service (which is related to your question, and which explain some problems around services, key component for extensibility).
Extract:
Why are services then so important if so many applications can be built without them? Well, services are the best known way to decouple software components from each other.
One of the most important aspects of services is that they significantly minimize class loading problems because they work with instances of objects, not with class names. Instances that are created by the provider, not the consumer. The reduction of the complexity is quite surprising
Not only do services minimize configuration, they also significantly reduce the number of shared packages.
Implement SOLID principles in your application.
1. Single responsibility principle: A class should have only a single responsibility (i.e. only one potential change in the software's specification should be able to affect the specification of the class
2.Open/closed principle: Software entities … should be open for extension, but closed for modification
3. Liskov substitution principle: Objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program
4. Interface segregation principle: Many client-specific interfaces are better than one general-purpose interface
5. Dependency inversion principle: One should Depend upon Abstractions. Do not depend upon concretions
Stackoverflow questions:
Example of Single Responsibility Principle
Is the Open/Closed Principle a good idea?
What is the Liskov Substitution Principle?
Interface Segregation Principle- Program to an interface
What is the Dependency Inversion Principle and why is it important?
You try to reach two competing goals:
The components of your software must expose a lot of themselves, so they can be reused
The components of your software must expose very little of themselves, so they can be reused
Explanation: To encourage code reuse, you should be able to extend existing classes and call their methods. This isn't possible when the methods are declared "private" and the classes are "final" (and can't be extended). So to meet this goal, everything should be public and accessible. No private data or methods.
When you release the second version of your software, you will find that many of the ideas of version 1 were plain wrong. You need to change many interfaces or your code, method names, delete methods, break the API. If you do this, many people will turn away. So in order to be able to evolve your software, the components must not expose anything that is not absolutely necessary - at the cost of code reuse.
Example: I wanted to observe the position of the cursor (caret) in an SWT StyledText. The caret is not meant to be extended. If you do it, you'll find that the code contains checks like "is this class in the package org.eclipse.swt" and a lot of methods are private and final and whatnot. I had to copy about 28 classes out of SWT into my project just to implement this feature because everything is locked down.
SWT is a nice framework to use and hell to extend.
Of course there is the famous Open Closed Principle - http://en.wikipedia.org/wiki/Open/closed_principle
Well it depends on the language.
In C/C++ I'm pretty sure there is a loadlibrary function that allows you to open a library at runtime and invoke it's exported functions. This is typically how it's done in C/C++.
In .NET, there is Reflection, which is offers similar (but more broad) to loadlibrary. There is also entire libraries built on Reflection like Managed Extension Framework, or Mono.Addins that does most of the heavy lifting for you already.
In Java, there is also Reflection. And there is the JPF (Java Plugin Framework) which is used in stuff like Eclipse IIRC.
Depending on what language you use I could recommend some tutorial/books. I hope this was helpful.
Plugin architecture is becoming very popular for its extensibility and thus flexibility.
For c++, Apache httpd server is actually plugin based, but a concept of module is used instead. Most of apache features are implemented as modules, like cache, rewrite, load balancing, and even threading model. It is a very modular software I ever saw.
And for java, Eclipse is definitely plugin based. The core of Eclipse is an OSGI module system which manage bundles, another concept for plugin. Bundle can provide extension points on which we can build modules with less efforts. The most intricate thing in OSGI is its dynamic characteristic, which means bundles can be installed or uninstalled at runtime. No stop-the-world syndrome any more!
Since I dont have enough rep points to leave a comment, I am posting this as an answer. SharpDevelop is an IDE for developing applications in C#/VB.NET/Boo. It has a pretty impressive architecture that allows itself to be extended in a number of ways - right from new menu items to development support for whole new languages.
It uses a bit of XML configuration to act as a glue layer between a core of the IDE and the plugin implementation. It handles locating, loading and versioning of plugins out of the box. Deploying new plugins is matter of simply copying in the new xml configuration file and the required assemblies (DLLs) and restarting the application. You can read more on this in the book "Dissecting a csharp application" by the original author(s) - Christian Holm, Mike Krüger, Bernhard Spuida of the application from here. The book doesnt seem to be available on that site, but i found a copy that might still be around here
Also found a related question here
Checkout "CAB" - Microsoft's Composition Application Building blocks Framework. I think they've got a "web version" of that too...
I have just started to develop a smart client application. These are two options I am considering.
Using Microsoft's System.AddIn namespace. Looks very promising, however it may be a little complex for our end solution.
Or the Smart Client - Composite UI Application Block from Microsoft
Recently, i have looked at taking components both the Composite UI Application Block and the System.AddIn namespace to build my own. Since source code is available for the CAB it is easy to extend. I think our end solution will be a light weight version of the CAB, definatly using the Unity Application Block
If you work with .Net, our research yielded two approaches: scripting and composition.
Scripting
You extend the functionality of what your classes can do by orchestrating them using scripts. That means exposing what is compiled in your favorite .Net language in a dynamic language.
Some options we found worth exploring:
IronPython
IronRuby
JavaScript: Jint, Jurassic and JavaScript .Net are good starting points.
Script.Net -> this one was the first one to call our attention.
Composition
If you start a project with .Net 4 or above, you must take a good look at the Managed Extensibility Framework (MEF). It allows you to extend the functionality of your apps in a plugin way.
The Managed Extensibility Framework (MEF) is a composition layer for
.NET that improves the flexibility, maintainability and testability of
large applications. MEF can be used for third-party plugin
extensibility, or it can bring the benefits of a loosely-coupled
plugin-like architecture to regular applications.
Managed Add-in Framework is also a good read.
MSDN: http://msdn.microsoft.com/en-us/library/dd460648.aspx
Codeplex: http://mef.codeplex.com/
Rather than re-inventing the wheel, use the frameworks in hand. Eclipse and Netbeans both support plugin based extensions. You have to work in Java though.
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In evaluating different systems integration strategies, I've come across some words of encouragement, but also some words of frustration over BizTalk Server.
What are some pros and cons to using BizTalk Server (both from a developer standpoint and a business user), and should companies also consider open source alternatives? What viable alternatives are out there?
EDIT: Jitterbit seems like an interesting choice. Open Source and seems to be nicely engineered. Anyone on here have any experience working with it?
BizTalk Server's key benefit is that it provides a lot of 'plumbing' around deployment, management, performance, and scalability. Through Visual Studio, it also provides a comprehensive framework for developing solutions, often with relatively little code.
The frustration and steep learning curve that others mention often comes from using BizTalk for the wrong purpose and from a misunderstanding about how to work with BizTalk and message-oriented systems in general. The learning curve is not as steep as most people suggest - the essential part of the underlying learning actually focuses on changing thinking from a procedural approach to a stateless message-based approach.
A drawback people often cite is cost. The sticker price can seem to be quite high; however, this is cheap in comparison to the amount you'd spend on developing and supporting features on your own.
Before you consider alternatives, or even consider BizTalk server, you should consider your organization's approach to integration and it's long term goals. BizTalk Server is great in cases where you want to integrate systems using a hub and spoke model where BizTalk orchestrates the activities of many applications.
There are other integration models too - one of the more popular ones is a distributed bus (don't confuse this with the term "Enterprise Service Bus" or ESB). You can also get BizTalk to work as a distributed bus and there are alternative solutions that provide more direct support. One of the alternate solutions is an open source solution called nServiceBus.
When considering whether to use a commercial product like BizTalk, verses something else (open source or developed in house), also consider maintenance and enhancements and the availability of the necessary skill-set in the marketplace.
I wrote some articles that go into more detail about the points I discussed here - here are the links:
Why BizTalk?
Top 10 BizTalk Mistakes
Extensibility Features in BizTalk Server
Open Source Integration with nServiceBus
My experience with BizTalk was basically a frustrating waste of time.
There are so many edge cases and weird little business logic tweaks you have to make when you are doing B2B data integration (which is probably the hardest part of any enterprise application) that you just need to roll your own solution.
How hard is it to parse data files and convert them to a different format? Not that hard. Unless you're trying to inject a bloated middleware system like Biztalk into the middle of it.
As a BizTalk consultant I have to agree at least partly with Eric Z Beard, there are a lot of edge cases that take up alot of time. But quite a few scenarios are handled extremly smooth as well, so it all depends IMO. But when you (Eric) call BizTalk bloated I have to disagree! We've found that the performance and reliability is excellent, it's flexible and comes with a lot of good adapters out of the box.
BizTalk needs to be used correctly,
I am a BizTalk developer and my experience with BizTalk is quite good.
Its reliable, performant, scalable, contains a lot of built in architectural patterns and build in components to make integration easy and fast, you get security, retries, secondary transports, validation, transformation etc... and what ever you dont have build in with BizTalk you can easily customized with .NET code, its basically a hard earned integration system and you get all this in one box.
BUT you need to know how to implement BizTalk correctly, not once I came across solutions that where implemented and often also architected incorrectly.
but the real benefit of BizTalk is that you can implement small solutions and scale up whilst most other integration systems from big vendors will only sell a whole integration pack which can cost much more.
BizTalk is considered the most complicated server from the house of Microsoft.
So any body saying BizTalk is not good dosent know BizTalk period.
We evaluated BizTalk at our company and were really disappointed.
We are using IBM WebSphere Transformation Extender (which has lots of (other) problems, too) and the mapping tool of BizTalk is a joke in comparison to WTX.
The graphical tool is not really usable for complex mappings (we have schemas with a few hundred fields in repeating groups) and if you do more than the usual "concat first name and last name to name" mappings, you will be tired of the graphical approach (for example the arguments of the functoids in the graphical mapper are not labeled and the order in which you connect fields to these arguments is important).
The XSLT-Mapper was usable but not really convincing, and even the microsoft rep told us to use a tool like XMLSpy for XSLT and load the resulting XSL file into BizTalk.
A third approach to mapping is to use C#-Code for the mapping, which was not acceptable for us as a general approach (we don't want to teach everyone C#).
In addition to the mapping tool we did not like the deployment in BizTalk. In order to deploy your process, you need to make lots of settings in different tools and places. We had hoped to find a mechanism like a WAR file for Java Web Applications in BizTalk, so that you can give one archive for your whole process solution to your administrator and he can deploy it.
We've been using BizTalk since version 2004, and now have a mix of versions 2006 R2 and 2004 running. I found that the learning curve was quite severe, and development time for solutions is not always quick. Those are definitely shortcomings. Where BizTalk really excels is in its fault tolerance, gauranteed delivery, and performance. You can rest assured that data will not get lost. Retry functionality and fault tolerance robustness is baked in so generally speaking if systems are down BizTalk will handle that and successful delivery will occur once systems come back on line. All these issues such as downtime, etc that are important in an integration scenario are handled by BizTalk.
Further, generally speaking when developing solutions BizTalk abstracts the communication protocols and data formats of the native systems by dealing with everything as xml, so when developing solutions, you typically don't have to wrote code specific to those systems, you use the BizTalk xml framework.
In the last year, we've implemented a java open source engine called Mirth for our HL7 routing. I found that for HL7 purposes, the HL7 adaptor for BizTalk is a challange to work with. Management dicated that we use Mirth for HL7 routing. Where BizTalk falls down in terms of learning curve, Mirth makes up. It is far easier to develop a solution. The problem with mirth is that it doesn't really have any gauranteed delivery. Most of the adaptors (except for hl7) have no retry functionality so if you wanted that you'd have to write your own. Second, Mirth can lose date if it goes down. I would call it very easy to use (although there is no documentation) but I'd be hard pressed to call it an enterprise solution. I'm going to check out jitterbit which was mentioned by someone else.
We used BizTalk for a couple of years, but gave it up for our own custom framework that allowed more flexibility.
There is always Sun's (now Oracle) OpenESB framework. Its generally speaking a smaller, lighter version of Biztalk but with roughly all the same features.
You do get to write more code with it, though.
Its Open Source as well.
In the OSS space (though I've never used them as a BizTalk replacement personally - this is anecdotal) you can use one of the Java/J2EE Messaging engines such as OpenMQ (which is the Sun enterprise one rebadged and without support). If you need Orchestration / Choreography (i.e. SOA/ESB pieces) on top of this, you could look into something like Apache Mule
My experience with BizTalk and doing B2B integrations is that most organizations do not truly do schema first design or fully understand xml standards for that matter. Most tend to weave objects and hope they materialize into meaninful schemas. In an enterprise environment, this is backwards.
BizTalk does have a learning curve, but once you get it you are rewarded with durability, performance, true scalability, and extensibility. Like most have said though, it best to make sure it meets your needs and contort your needs to BizTalk.
In the past I have worked with BizTalk 2004 through 2009, and another product called webMethods.
I have no direct experience with JitterBit, but I have heard very good things from coworkers.
I came across Apatar (unable to post url, but Google finds it) while looking for a solution cheaper than BizTalk. I have yet to try this out.
My last company had many problems with BizTalk being too complex and ridged, but I can’t help but think this was mainly down to the implementation the consultant did.