I have a bunch of Java code which was written using the Hibernate framework, originally destined to have a front end written using JSPs. However, the requirements for the front end have changed, and we've decided that a desktop client (which will be written in .NET) is a better match for our users.
I don't really want to waste the code that's already been written - can anybody suggest a good set of tools for writing a document-based web services interface that we will be able to access from .NET?
Thanks,
Jim
If you truly want a document based service interface (rather than an RPC style web service architecture), your best bet is going to be creating a SOAP based web service interface.
A quick glance at the Java site shows that the Metro stack might help a bit:
Java Web Services at a Glance
We're developing an application with the exact architecture you describe for a finance application. We reviewed several different options, and have finally landed on using compressed CSV over HTTP.
CSV was chosen since the vast majority of data was going to be displayed in a grid on the front end, we had very large result sets >250k rows on a regular basis, and it compresses really really well.
We also looked at using:
ICE, but declined on that due to licensing costs and the need to reinvent so much.
Google's protocol buffers via servlets, but declined on that due to lack of C# support (as of last fall).
Compressed XML using WOX, but declined on that due to lock-in to a small thesis project for support and XML being too verbose.
The industry supports a couple of different options as well:
SOAP, but that has its own well documented issues.
IIOP, J-Integra has a product called Espresso which will allow you to do RMI from a front end.
I'd personally use some lightweight RPC protocol, be it XML-RPC or a homegrown one. SOAP, IMO, is way too fat and is not as interoperable as it's supposed to be. The simpler the better.
We have a quite large application using a Java RMI server and IIOP.NET for interoperability. We have used IIOP.NET with the Sun RMI and the Bea Weblogic (now Oracle) without major issues.
Related
I am working on an existing system written using .NET 2.0 remoting to integrate a number of embedded clients to a central server. Due to a number of issues, it has become desirable to rewrite the server in Java. Updating the clients is not really viable at this point; there are many of them and they are geographically scattered, so an update would be potentially expensive. To this end, I was wondering what solutions are available to implement a Java server that would be compatible with the existing over-the-wire protocol?
I am aware of JNBridgePro, but it is unfortunately too expensive for our current budget. I also have the CD from the book Microsoft® .NET and J2EE Interoperability Toolkit (Microsoft Press), which has a copy of a piece of software called "ja.net" from Intrinsyc Software that promises to fulfill this function, but in order to use it you need to obtain a licence from Intrinsyc and their web site is not responding (perhaps they have gone out of business since the book was published?).
Are there any others I'm not aware of?
No, no such thing (except custom commercial solutions).
However, if you are up to an in-house solution, you can:
Write your own .NET remoting adapter, which sits between the .NET clients and the Java server.
The .NET adapter translates the requests to something known by the Java server (maybe a web service interface, via SOAP) and the same for the responses.
So, the .NET adapter would be something like a pass-through and mapping component, with no actual logic. This way all logic can be in the Java server (which seems to be what you want).
It could take some time to do it, but it depends directly on the number of clients you have and on the number of types of requests and responses.
Our frontend is simple Jetty (might be replaced with Tomcat later on) server. Through servlets, we are providing a public HTTP API (more or less RESTful) to expose our product functionality.
In the backend, we have a Java process which does several kind of maintenance tasks. While the backend process usually does it own tasks when it's time, now and then, the frontend needs to wake-up the backend to execute a certain task in the background.
Which (N)IO library would be ideal for this task? I found Netty, Grizzly, kryonet and plain RMI. For now, I am inclined to say Netty, it seems simple to use and it is probably very reliable.
Does any of you have experience in this kind of setups? What would your choice be?
thanks!
Try to translate this document which answer to your question.
http://blog.xebia.fr/2011/11/09/java-nio-et-framework-web-haute-performance/
This society, as french famous Java EE experts, did a lot of poc of NIO servers in the context of a french challenge sponsored by VmWare (USI2011). It was about building a simple quizz app that can handle a load of 1 million connected users.
They won that challenge with great results.
Their implementation was Netty + Gemfire and they only replaced the CachedThreadPool by a MemoryAwareThreadPool.
Netty seems to offer great performances, and is well documented.
They also considered Deft, inspired by Tornado (python/facebook) but it's still a bit immature for them
Edit: here's the translated link provided in the comments
My preference is Netty. It's simple yet flexible. Very fast and the community around Netty is awesome.
The company I work for is currently evaluating CoralReactor. It is a commercial software but it has the easiest API I have ever seen for Java NIO. My personal opinion is that Netty makes things too complicated, especially if you want to go garbage-free and single-threaded, which are a requirement for many companies from the finance, advertisement and game industry.
I would decouple them by using JMS, just have some (set of) control queues your backend sits there listening on and you're done. No need to write a custom nio api here.
One sample provider is hornetq. This can be run as an in process jms broker as well, it uses Netty under the covers.
We have what I think is a fairly typical client/server architecture, with a frontend written in .NET, displaying data sent from a backend written in Java.
Currently, we use a custom message-based framework for transmitting data snapshots and updates down to clients. This might be upgraded; although the basic java service/.net client setup is set in stone, we want to look at replacements for the message framework, for example WPF MVVM (with an eye on Sliverlight), with databindings to java web-services, or perhaps Coherence.
I was wondering what experiences others have had with this and other approaches (obviously there's no golden bullet for all situations...).
Our requirements are that the clients can show large, frequently updating and editable datasets, primarily in grids.
Update
I've accepted that REST/SOAP is the standard way to do it, but I'd still be interested to hear any other approaches, especially from a performance point of view.
Web services is the most common choice:
RESTful service - more flexible, no strictly defined schema
SOAP service - rigid schema, less flexible
Checkout protobuf, which is a good platform agnostic protocol.
Does anyone have a real-world experience in building such a project? I'd like to move away questions about "is it good idea or not", but focus on possible solutions. I see one simple way - HTTP GET/POST + xml/json - and one more elegant - AJAX/DWR. As for the first one - I understand that it is possible, but needs quite a lot coding. As for second way - is it possible to use Java DWR engine with PHP front-end? Is DWR language-independent for client side (as it uses just JavaScript)?
Would it be a problem, that client page was generated by one web server (for example, apache+php) and served on server-side by another (for example, tomcat)? I suspect, that Tomcat will complain about sessions. Can this problem be fixed with allowing cross-domain AJAX?
Thank you in advance.
Denis.
If what you want to do is (as I suspect) to use PHP to assemble your web pages while the "business logic" is written in Java, I would suggest using PHP/Java Bridge (LGPL and MIT licenses)
Both Java and PHP are server-side technologies. Your "front-end" will be written using HTML, CSS, and JavaScript - although you could certainly use PHP (or JSP) templates to render portions of the front-end.
If you are using PHP as the "front-end", then you would need it to act as a proxy, passing requests back to the Java web server.
I've worked on a project that uses a Java 'backend' and a mod_perl 'frontend'. For the naysayers, this is because the Java is providing service/API facilities, it's not and shouldn't be involved in dealing with UI, be they HTML, WAP, SMTP, SOAP, etc.
For historical reasons the mod_perl talks XML-RPC. It's not a route I'd recommend at this stage. Java, Perl and PHP can quite happily handle far more JSON type transactions due to lower encoding/decoding overhead. Also, in a mod_perl (though not PHP) environment it's possible to run JSON-RPC easily over a persistent connection, reducing the overhead even further.
There are plenty of benefits to this approach, including separate upgrades to the various UIs, stability of the service layer, and distinct responsibilities for each layer.
Downsides include delays getting service improvements live, more complicated development, staging and test environments, a taller barrier to entry for new developers, more documentation and management.
For the "Java front to back" guys, this is a similar type approach to using an OSGi container, only using more domain suitable languages; Java for heavy lifting, scripts for more fluid, text based interfaces.
I am not sure exactly what I am asking....The guys that do the software development for the company I work for write everything in VB. I am currently the Web developer for this company and I specialize in Flex apps. I am thinking about expanding into their area. But I do not want to do VB, I don't mean to bash on VB but the coding syntax is not for me. So I am wondering if Java can integrate with VB? Also not sure if it matters but I think everything they do is procedural, and I will be doing OOP.
Thanks.
There are lots of integration opportunities, but before examining them, if I were you I would re-examine the question itself.
It should be exceptional to introduce a new language into an established project. The desires or aesthetic preference or skillset of a single developer is not a good enough justification to do so. Introducing a new language into a project should be a strategic decision for the project, not a backhanded one.
If you do choose to expand the core languages used to develop the system,
COM interop
is possible with JACOB. I believe IBM has a bridge as well.(Check alphaworks)
Java-.NET bridging
is possible via JNBridge and other bridges. This makes sense only if VB.NET is in use.
SOAP, XML document exchange, REST
suitable over a services boundary. It requires TCP or HTTP or some network protocol.
common data stores
can serve as a rendezvous point. Both Java and VB can read and update data in SQL Server, Oracle, MSMQ, MQSeries, and so on. Even a filesystem can be an integration point.
Think of data format as related to, but ideally independent of, the integration mechanism. What I mean is: You can use an XML document for integration, whether it is stored in a database, or sent over a REST interface, or stored in a filesystem, or put/get on a queue. You can use a comma-separated file over any of those mechanisms as well.
Potentially they could expose a service layer via soap or something simpler? Also you could always work against the same database with different languages however unless most of the logic is in stored procedures (not necessarily recommending this approach) then you end up with repeated code.
Not really. Java uses CORBA for interop, and VB uses COM for interop. You may be able to make a bridge using JNI, but I understand that can be quite the pain.
I haven't done this by I believe you have the following options:
Use the Java-COM bridge, as VB uses COM. This library was already mentioned here several times
If you are using VB.net, you probably use hessian, As it has both Java and C# implementations.
You could bridge the two using a C/C++ adapter to map JNI calls with COM. But that would be horrible. I hope there is a better solution, but my understanding is that it is pretty hard to integrate .NET code and Java as both vendors (Sun and Microsoft) don't have any incentive to streamline that kind of development.