Is StatementBuilder for external use? - spring-data-jdbc

I was implementing a project with spring-data-jdbc and I found the Statement Builder API. I could this API be used for building native sql repositories?

At this point the StatementBuilder API is considered internal and use outside Spring Data is not encouraged, because it might undergo breaking changes without the normal cycle of deprecation.
That said it is a pretty isolated piece of code with a friendly OSS license so in many cases it might be an acceptable risk to use it with the fallback plan to clone it into an own package should it change in a way that is not useable for you.

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Convert Resuable ErrorHandling flow in to connector/component in Mule4

I'm Using Mule 4.2.2 Runtime. We use the errorHandling generated by APIKIT and we customized it according to customer requirement's, which is quite standard across all the upcoming api's.
Thinking to convert this as a connector so that it will appear as component/connector in palette to reuse across all the api's instead copy paste everytime.
Like RestConnect for API specification which will automatically convert in to connector as soon as published in Exchange ( https://help.mulesoft.com/s/article/How-to-generate-a-connector-for-a-REST-API-for-Mule-3-x-and-4-x).
Do we have any option like above publishing mule common flow which will convert to component/connector?
If not, which one is the best way suits in my scenario
1) using SDK
https://dzone.com/articles/mulesoft-custom-connector-using-mule-sdk-for-mule (or)
2) creating jar as mentioned in this page
[https://www.linkedin.com/pulse/flow-reusability-mule-4-nagaraju-kshathriya][2]
Please suggest which one is best and easy way in this case? Thanks in advance.
Using the Mule SDK (1) is useful to create a connector or module in Java. Your questions wasn't fully clear about what do want to encapsulate in a connector. I understand that you want is to share parts of a flow as a connector in the palette, which is different. The XML SDK seems to be more inline with that. You will need to make some changes to encapsulate the flow elements, as described in the documentation. That's actually very similar to how REST connect works.
The method described in (2) is for importing XML flows from a JAR file, but the method described by that link is actually incorrect for Mule 4. The right way to implement sharing flows through a library is the one described at https://help.mulesoft.com/s/article/How-to-add-a-call-to-an-external-flow-in-Mule-4. Note that this method doesn't create a connector that can be used from Anypoint Studio palette.
From personal experience - use common flow, put it to repository and include it as dependency to pom file. Even better solution - include is as flow to the Domain app and use it alone with your shared https connector.
I wrote a lot of Java based custom components. I liked them a lot and was proud of them. But transition from Mule3 to Mule4 killed most of them. Even in Mule4 Mulesoft makes changes periodically which make components incompatible with runtime.

Test endpoints compliance against openapi contract in Spring Boot Rest

I am looking for a nice way to write tests to make sure that enpoints in Spring Boot Rest (ver. 2.1.9) application follows the contract in openapi contract.
In the project I moved recently there is following workflow: architects write contract openapi.yml and developers have to implement endpoint to compliance the contract. Unfortunately a lot of differences happen and this test have to catch such situation and it is not possible to change this :(
I was thinking about the solution to generate openapi.yml from current ednpoints and compares it somehow but wonder if there is some out of the box solution.
I was thinking about the solution to generate openapi.yml from current ednpoints and compares it somehow but wonder if there is some out of the box solution.
In a general case, even the generated spec may not match the actual app behavior because some things can't be expressed with Open API. However, it still could be helpful as a starting point.
Open API provides a way to specify examples, that could be used to verify the contract. But the actual schemas might be a better source of expectations.
I want to note two tools that can generate and execute test cases based only on the input Open API spec:
Schemathesis uses both examples and schemas and doesn't require configuration by default. It utilizes property-based testing and verifies properties defined in the tested schema - response codes, schemas, and headers. It supports Open API 2 & 3.
Dredd focuses more on examples and provides several automatic expectations. It supports only Open API 2, and the third version is experimental.
Both provide a CLI and could be extended with various hooks to fit the desired workflow.
I'd suggest passing the contracts (as a spec you mentioned) to Schemathesis and it will verify if all schemas and examples are handled correctly by your app.

Lightweight Real-time Ajax, WebSocket, or Similar for Scala

Our requirements for a real-time web framework include:
lightweight framework
scala support on server side
flexible on communication mechanism : may be Ajax, Server Sent Event or WebSocket.
relatively little changes required to client html.
E.g. using the WebSockets js library is fine
introducing significant compile time/server side page processing is not. E.g. Play routing annotations are not acceptable
must have working examples for both:
web clients
server to server communications
fully functional build. Preferably sbt, but maven maybe acceptable
I have evaluated the following frameworks: and each one of them has one or more drawbacks that make usage within our application less than desirable.
Play: somewhat heavy, but more importantly it introduces custom annotations/processing into the html page. We need VANILLA html pages.
Spray: closer to the mark. But although I found a number of example applications, the actor-based communication is not working in those examples. The SimpleServer example has a built-in "cases" counter (from SimpleClient) that do not work as given: they could certainly be made to work .. eventually..
atmosphere: lacking examples
jetty, netty: lacked fully functional examples buildable within sbt or maven
socko : The markdown essentially stipulates using eclipse/scala-IDE for running tests/doing development. That is a non-starter for us (IJ shop). It was unclear how to run examples and/or start their servers from sbt / command line.
I ended up writing a fair amount of custom code wrapped around Netty. After it is in better shape I may drop it on GitHub.
http://xitrum-framework.github.io/ is actively developed and contains SocksJs support. It is rather lightweight, you can directly annotate routes on actors and they become exposed on the web.

Suitable frameworks for ERP like application

I want to create a production management system to be used by a small manufacturing firm. The system will allow to document different stages in manufacturing of equipment. The requirements are as follows:
1.Non browser based interface.Need something like Swing or AWT based.While i understand the convenience of implementing a browser based solution,the business owner insists on a non browser interface
2.Accessed from multiple systems.These systems will allow CRUD operations on the central system (Thin Client?)
3.The application will not have more than 3 concurrent users.
I need some advice regarding what would be a good path for this kind of application.Currently, i'm thinking of using Griffon with RMI. However, i don't have much development experience.Read a bit about Apache River (Jini) too.Would it be a good idea to use Griffon with RMI?
Please provide some advice. Thanks.
EDIT:after some reading, i've decided to use more mainstream frameworks.So, Griffon is not an option. How about Jini(Apache River) or OSGI (Apache Felix)?
Hmm how is that a project which recently moved out of the incubation phase be considered mainstream vs a project that's been used in production for more than 3 years now? Anyway, Apache River gives you access to Jini technology and nothing more; meaning you can't achieve item #1 of your list with River alone. River may use RMI for accessing remote resources, however you can use RMI directly, or try out DRMI, Kryonet, Hessian/Burlap, Spring's HTTP Invoker, Protocol Buffers, Avro/Thrift, REST, SOAP, ZMQ and many more.
Even if you choose one of these options and/or River you still have to define the following things
application structure (file structure and runtime behavior)
build setup
dependency management
testing profiles
packaging
deployment strategies
These things and more are what Griffon brings to the table. As you may have noticed the framework allows you to build up applications by adding plugins, reducing thew amount of time you must allot for hunting down dependencies, setting up bootstrap mechanism and getting things done. On the subject of remoting technologies have a look at the different options Griffon has to offer http://artifacts.griffon-framework.org/tags/plugin/remoting
Even more, you can also combine OpenDolphin (http://open-dolphin.org/dolphin_website/Home.html) with Griffon. There's even an example application found at the opendolhpin repository showing a full client-server application (build with Griffon, Grails and OpenDolphin) https://github.com/canoo/open-dolphin/tree/master/dolphin-griffon-crud
With what seems to be your current understanding of the problem, I would not recommend OSGI, especially for a small manufacturing firm (Possible maintenance issues, depending on the "personel").
The main reason why I wouldn't advocate JINI or OSGI in your case is because of what you said
However, i don't have much development experience.
JINI (Apache River) is a viable option as long as you fully understand the concepts of LookupService and service registrations, etc. There's tons of RMI going on here with possible firewall implications...
OSGI is not difficult but you may have issues deciding how to structure your applications as well as interacting with services, etc.
Try to stick to the simplest approach that you can handle for the implementation (Flexible design in mind): Make it work and then improve it.
There are simple Web Services options such as Spring Remoting (over http/https for example), unless Spring introduces too many concepts and headaches for your app.

Should I build a REST backend for GWT application

I am planning a new application and have been experimenting with GWT as a possible frontend. The design question I am facing is this.
Should I use
Option A: GWT-RPC and build the app quickly
Option B: Build a REST backend using Spring MVC 3.0 with all the great #Controller, #Service, #Repository annotations and build a client side library to talk to the backend using the GWT overlay features and the GWT Request builder?
I am interested in all the pros and cons and people experiences with this type of design?
Ask yourself the question: "Will I need to reuse the server-side interface with a non-GWT front-end?"
If the answer is "no, I'll just have a GWT client": You can use GWT-RPC, and take advantage of the fact that you can use your Java objects both on the server and the client-side. This can also make the communication a bit more efficient, at least when used with <inherits name="com.google.gwt.user.RemoteServiceObfuscateTypeNames" />, which shortens the type names to small numeric values. You'll also get the advantage of better error handling (using Exceptions), type safety, etc.
If the answer is "yes, I'll make my service accessible for multiple kinds of front-ends": You can use REST with JSON (or XML), which can also be understood by non-GWT clients. In addition to switching clients, this would also allow you to switch to a different server implementation (maybe non-Java) in the future more easily. The disadvantage is, that you'll probably have to write wrappers (JavaScript Overlay Types) or transformation code on the GWT client side to build nice Java objects from the JSON objects. You'll have to be especially careful when you deploy a new version of the service, which brings us back to the lack of type safety.
The third option of course would be to build both. I'd choose this option, if the public REST interface should be different from the GWT-RPC interface anyway - maybe providing just a subset of easy to use services.
You can do both if use also use the RestyGWT project. It will make calling REST based JSON resources as easy as using GWT-RPC. Plus you can typically reuse the same request response DTOs from the server side on the client side.
We ran into the same issue when we created the Spiffy UI Framework. We chose REST and I would never go back. I'd even say GWT-RPC is a GWT Anti-pattern.
REST is a good idea even if you never intend to expose your REST endpoints. Creating a REST API will make your UI faster, your API better, and your entire application more maintainable.
I would say build a REST backend. In my last project we started by developing using GWT-RPC for the first few months, we wanted fast bootstrapping. Later on, when we needed the REST API, it was so expensive to do the refactoring we ended up with two backend APIs (REST and RPC)
If you build a proper REST backend, and a deserialization infra on the client side (to transform the json\xml to GWT Java objects) then the benefit of the RPC is almost nothing.
Another sometimes forgotten advantage of the REST approach is that it's more natural to the browser running the client, RPC is a propitiatory protocol, where all the requests are using POST. You can benefit from client side caching when reading resources in the standard way.
Answering ams comments:
Regarding the RPC protocol, last time I "sniffed" it using firebug it didn't look like json, so I don't know about that. Though, even if it is json based, it still uses only the HTTP POST method to communicate with the server, so my point here about caching is still valid, the browser won't cache POST requests.
Regarding the retrospective and what could have done better, writing the RPC service in a resource oriented architecture could lead later to easier porting to REST. remember that in REST one usually exposes resources with the basic CRUD operations, if you focus on that approach when writing the RPC service then you should be fine.
The REST architectural style promotes inspectable messages (which aids debugging and security), API evolution, multiple platforms, simple interfaces, failure recovery, high scalability, and (optionally) extensible systems via code on demand. It trades per-interaction performance for overall network efficiency. It reduces the server's control over consistent application behavior.
The "RPC style" (as we speak of it in opposition to REST) promotes platform uniformity, interface variability, code generation (and thereby the ability to pretend the network doesn't exist, but see the Fallacies), and customized interactions. It trades overall network efficiency for high per-interaction performance. It increases the server's control over consistent application behavior.
If your application desires the former qualities, use the REST style. If it desires the latter, use the RPC style.
If you're planning on using using Hibernate/JPA on the server-side and sending the resulting POJO's with relational data in them to the client (ie. an Employee object with a collection of Phones), definitely go with the REST implementation.
I started my GWT project a month ago using GWT RPC. All was well until I tried to serialize an object from the underlying db with a One-To-Many relationship in it. And got the dreaded:
com.google.gwt.user.client.rpc.SerializationException: Type 'org.hibernate.collection.PersistentList' was not included in the set of types which can be serialized by this SerializationPolicy
If you encounter this and want to stay with GWT RPC you will have to use something like:
GWT Request Factory (www.gwtproject.org/doc/latest/DevGuideRequestFactory.html) - which forces you to write 3+ classes/interfaces per POJO you want to share with the client. OUCH!
Gilead (sourceforge.net/projects/gilead/) - which appears to a dead project.
I'm now using RestyGWT. The switch was fairly painless and my POJO's serialize without issue.
I would say that this depends on the scope of your total application. If your backend should be used by other clients, needs to be extendable etc. then create a separate module using REST. If the backend is to be used by only this client, then go for the GWT-RPC solution.

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