Is JBI, SCA also considered an integration framework. What are all the integration framework available.
JBI and SCA fairly different technologies. I will comment on SCA. If by "integration framework" you mean a technology that assists in connecting services, then I would say, yes.
Fabric3 (an SCA runtime) uses those precise terms: http://docs.fabric3.org/
Related
I have read that Zeebe (https://zeebe.io/) from Camunda is created specifically for Microservices Orchestration. I know there is some difference related to performance.
My question is "Can I achieve the same thing using Camunda what I can do with Zeebe?"
I noticed that Camunda enterprise provides many features that are not provided in the free version or in Zeebe like BPMN deployment, History of previous workflows. I want to get those features for microservice orchestration. My guess is that I will not get if I use Zeebe.
These are multiple questions in one.
Yes, you can do Microservice orchestration with Camunda BPM. As you pointed out correctly, the difference is the architecture of the workflow engine itself, not the use cases you can leverage it for.
Yes, there is a Camunda BPM enterprise edition that has features that are not in the community edition, see: https://camunda.com/enterprise/
Zeebe will provide the same capabilities eventually. Given that it is relatively young it does not have all features of Camunda BPM on this end. But to relate to your example, Operate can show history instances but is also not free for commercial use. Zeebe is also provided as managed service: https://camunda.com/products/cloud/
Is it possible to integrate play framework with OSGI to create plugable components? Did someone try it?
If you mean "create Play modules with OSGi", then no, it's not supported
If you mean "deploy Play as an OSGi module" then no, it's not supported
And to be fair, there's no reason to push its support. You can read these thoughts from Spring founder on OSGi, as an example. OSGi would add extra complexity to Play, while the main aim of Play is to be a rapid development platform, simple to use, removing some Java conventions (like Sessions). It would kind of defeat the purpose.
If we're discussing Play 2 then it's definitely worth acknowledging that an important and integral part of Play now is Akka, which could be seen as an alternative to OSGi. Philosophically I think Akka has a lot in common with the core principles of Play and Scala (a functional, stateless, NIO approach), while OSGi is more aligned with the Java EE/Spring camp.
That's not to say that Akka and OSGi are wholly mutually-exclusive: Akka's documentation suggests you can deploy Akka as an OSGi bundle and create some mutant app which has Akka actors firing up via an OSGi bundle.
But to answer the question, no, Play doesn't do OSGi, but it very much does do Akka.
I am trying to design the standards and patterns for implementing portlets/web gadgets with the main goal of maximizing interoperability if those components were hosted in a Java app server framework or within an existing ASP.NET technology (SharePoint webparts), or a client side-only framework.
Is there any guidance anywhere of the parts of different portlet standards that are shared between most portal frameworks?
Is the best I can hope for is to adhere to the JSR 168 and 286 standards and hitch my wagon to Java?
What about WSRP?
What are the advantages/disadvantages of Seam over Spring? Why would I use Seam in lieu of Spring?
Is there anything that can be done in Seam that can't be done in Spring? Anything in Spring that can't be done in Seam?
What about stateful/stateless architecture? I am a Spring user, so I am biased, naturally.
Why Spring?
Cleaner code
Streamlined application configuration
Nice integration with popular open source products
First class AOP support
Enterprise-scale security: Acegi
Highly flexible MVC
Abstracted data access (JDBC is OK)
Enterprise Java without EJB
Testing is easy
Why Seam?
Merge Java EE 5 standards (EJB 3.0, JPA, JSF, Annotation) seamlessly
Stateful by design
Bijection
Integrated Ajax (ICEfaces and Ajax4JSF)
Business process integration (jBPM)
Business rules integration (Drools)
Workspace management
Deliver complete stack (from JBoss & RedHat)
Seam Text and EL enhancements
Probably will be a standard (JSR-299: Web Beans)
From Framework Deathmatch: Spring vs Seam. Thomas Wiradikusuma (Spring). Joshua Jackson (Seam). Java User Group Indonesia. JaMU 07.03. March 17, 2007 power point presentation here
although seam does have many advantages over spring, there is a magic word that really is worth paying attention to and this is PERFORMANCE!!! if you are not worried about performance issues I would go with seam. From the other hand if you want your application to be as fast as possible and your hardware is limited I would use spring. I am not saying that you can not develop fast applications with seam, but in order to do this you really need to know what you are doing. I have used both of them (i am not a guru in any of them) and what I found out is that although spring needs more effort to build what you want, at the end the result is more flexible and is performing better. I do not think that there is something that can be done in one framework that it can not be done in the other, saying that, remember that I am not an expert to any of those.
Seam will give you a pretty, ah, seamless, integration between the components that make up the seam stack. All very nice as long you keep within that stack, and within the seam model and foing things. It all starts to look a little less convincing as soon as you start doing something unusual, though.
If it's not too much of a generalisation, Seam is very "microsofty" in that regard. This isn't a bad thing, it's just a stylistic thing. Spring is more open-ended and takes more effort to get going, but it's ultimately more flexible, and a lot more open.
You can use Spring and Seam together - Spring for backend components, Seam for enhancement of web layer (JSF/GWT/Wicket) and other stuff. Seam offers a lot of Spring functionality (i.e. IoC container, transaction managment) - in your project you can decide - witch implementation to use.
More details on integrating Seam with Spring - "Seam in Action - free bonus chapter"
Let's compare the two.
What is common?
Both are open source, follow MVC architecture and has a servlet based front controller.
Advantages of Spring MVC
Extension of Struts.
View can be developed using JSP and HTML. You can also plugin other's like PHP or velocity.
Has large number of controllers predefined.
Integrated out of the box with Spring framework.
Advantages of Seam
Extension of JSF
View can be developed using JSF component library. There are large number of vendors to choose from.
Integrates JPA entities with Web layer
Annotation based validation
Integrates with EJB 3.0
Out the box jBPM support which provides process flow definitions.
Integrates with Drools where you can define web layer business rules.
Good community support.
Conclusion
Since Seam is built on JSF, it has large number of UI Component libraries to pick from. It reuses Java EE stack better. It has lot of interesting modules integrated beforehand.
Spring MVC is built on top of Struts and Spring, so it will reuse Spring framework stack far better than others. But the view is built using JSP, so we have to rely on JSP tag library vendors to build rich components.
Seam framework would be a better choice as Spring framework is anyway extensible enough to be leveraged by Seam.
I have been trying to understand a bit more about the wider picture of OSGi without reading thru the entire specification. As with so many things, the introduction to what OSGi actually is was probably written by someone who had been working on it for a decade and perhaps wasn't best placed to put themselves in the mindset of someone who knows nothing about it :-)
Looking at Felix's example DictionaryService, I don't really understand what is going on. Is OSGi a distinct instance of a JVM into which you load bundles which can then find each other?
Obviously it is not just this because other answers on StackOverflow are explicit that OSGi can solve the dependency problem of a distributed system containing modules deployed within distinct JVMs (plus the FAQ keeps talking about networks).
In this latter case, how does a component running in one JVM interact with another component in a separate JVM? Can the two components "use" each other as if they were running within the same JVM (i.e. via local method calls), and how does OSGi manage the marshalling of data across a network (do you have to use Serializable for example)?
Or does the component author have to use some other distinct mechanism (either provided by OSGi or written themselves) for communication between remote components?
Any help much appreciated!
Yes, OSGi only deals with bundles and services running on the same VM. However, one should note that it is a distinct feature of OSGi that it facilitates running multiple applications (in a controlled way and sharing common modules) on the same JVM at all.
When it comes to accessing services outside the clients JVM, there is currently no standardized solution. Paremus Infiniflow and the derived open-source project Newton use an SCA approach. The upcoming 4.2 release of the OSGi specs will address one side of the problem, namely how to use generic distribution software in such a way that it can bring remote services into the client's JVM.
As somebody mentioned R-OSGi, this approach also deals with the other side of the problem, being how to manage dependencies between distributed OSGi frameworks. Since R-OSGi is not generic distribution software but explicitly deals with the lifecycle issues and dependency management of OSGi bundles.
As far as I know, OSGi does not solve this problem out of the box. There are OSGi-bundles, for example Remote OSGi, which allow the programmer to distribute services across a network.
Not yet, i think it's being worked on for the next release.
But some companies have already implemented distributed osgi. One i'm aware of is Paremus' Infiniflow (http://www.paremus.com/products/products.html). At linkedin they are also working on this. More info here: Building Linkedin next gen architecture with osgi and here: Matt raible: building linkedin next gen architecture
Here's a summary of the changes for OSGI 4.2: Some thoughts on the OSGi R4.2 draft, There's a section on RFC-119 dealing with distributed OSGi.
AFAIK, bundles are running in the same JVM, but are not loaded using the same class loader (that why you can use two different versions of the same bundle at the same time).
To interact with components in another JVM, you must use a network protocol such as rmi.
The OSGi alliance is working on a standard for distributed OSGi:
http://www.osgi.org/download/osgi-4.2-early-draft2.pdf
There even is an early Apache implementation of this new standard:
http://cxf.apache.org/distributed-osgi.html
#Patriarch24
The accepted answer to this question would seem to indicate otherwise (unless I'm misreading it). Also, taken from the FAQ:
The OSGi Service Platform provides the functions to change the composition dynamically on the device of a variety of networks, without requiring a restart
(Emphasis my own). Although in the same FAQ it describes OSGi as in-VM.
Why am I so confused about this? Why is such a basic question about a decade-old technology not clear?
The original problem of OSGI was more related to distribution of code (and then configuration of bundle) than to distribution of execution.
People looking at distributed components are rather looking towards SCA
The "introduction" link is not really an intro, it is a FAQ entry. For more information, see http://www.osgi.org/About/WhatIsOSGi Not hard to find I would think.
Anyway, OSGi is an in-VM SOA. That is, the OSGi Framework is about what happens inside the VM, it provides a framework for structuring your application inside the VM so you can built it too a large extent from components. So the core has nothing to do with distribution, it is completely oblivious of who implements the services, it just provides a mechanism for modules to meet each other in a loosely coupled way.
That said, the µService model reifies the joints between the modules and it turns out that you can build support on top of the framework that provides distribution to the other components. In the last releases we specified some mechanisms that make this standardized in the core and provide a special service Remote Service Admin that can manage a distributed topology.
If you are looking for a distributed OSGi centric Cloud runtime - then the Paremus Service Fabric ( https://docs.paremus.com/display/SF16/Introduction ) provides these capabilities.
One or more Systems each consisting of a number of OSGi assemblies (Blueprint or Declarative Services) can be dynamically deployed and maintained across a population of OSGi runtime Frameworks (Knopflerfish, Felix or Equinox).
A light weight RSA remote framework is provided which provides Service discovery by default using DDS (a seriously good middleware messaging technology) - (thought ZooKeeper and other approach can be used). Currently supported re-moting protocols include RMI and Avro.
Regards
Richard