I want to make database queries in my Jersey REST webapp. The ideal situation would be to find a way where the database connection is initialised once at the first app run. Afterwards I only get the instance of DAOFactory object in my REST class and make the queries in the methods. I am using mysql connector. Is there a way to find a way to do it in Jersey? In JSF it was possible - I just used an application-scoped bean when I run the code. Moreover it would be good if I could access the ServletContext object inside this method cause I would like to use it's getResourceAsStream() method to read the database connection parameters from WEB-INF/dao.properties file. But the 'only once per app initialisation' is the crucial part here.
Related
I have this SpringBoot server app using PostgreSQL database if it's up and sending error response if it's down. So my app is running regardless the database connection.
I would very much like to test it (jUnit / mockmvc).
My question is very simple, yet I did not find the answer online:
how does one simulate a database connection loss in SpringBoot?
If anyone wants, I can supply code (project is up at https://github.com/k-wasilewski/workshop/)
Have you thought of Testcontainers? You can spin up your docker image through a Junit test and make your spring boot use that as your database.
Since you use junit, you can start/stop this container at will.
This will generate a test which creates the condition you are looking for and write code as to what to expect when the database is down.
Here are some links to get started,
Testcontainers and Junit4 with Testcontainers quickstart - https://www.testcontainers.org/quickstart/junit_4_quickstart/
Spring boot documentation - Use Testcontainers for integration testing
https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-testcontainers
Testcontainer github link example for springboot app
https://github.com/testcontainers/testcontainers-java/tree/master/examples/spring-boot
Testcontainer - Generic container javadoc. You can find methods for start/stop
container here. call from your Junit.
https://javadoc.io/static/org.testcontainers/testcontainers/1.12.4/org/testcontainers/containers/GenericContainer.html
You can implement your own Datasource based on DelegatingDataSource and then let it throw exceptions instead of delegating when ever you want to.
I've done this before by creating a Spring Boot test configuration class that created the DataSource and wrapped it in a Java proxy. The proxy simply passed method calls down to the underlying DataSource, until a certain flag was set. Once the flag was set, then any method called on the proxy would throw an exception without calling the underlying DataSource. Essentially, this allowed me to "bring the database down" or "up" simply by flipping the flag.
In OSB Layer when the endpoint uri is changed, I need to alert the core group that the endpoint has changed and to review it. I tried SLA Alert rules but it does not have options for it. My question is, the endpoint uri should be saved somewhere in the underlying database. If so what is the schema and the table name to query it.
URI or in fact any other part of OSB artifact is not stored in relational database but rather kept in memory in it's original XML structure. It can be only accessed thru dedicated session management API. Interfaces you will need to use are part o com.bea.wli.sb.management.configuration and com.bea.wli.sb.management.query packages. Unfortunately it is not as straightforward as it sounds, in short, to extract URI information you will need to:
Create session instance(SessionManagementMBean)
Obtain ALSBConfigurationMBean instance that operates on SessionManagementMBean
Create Query object instance(BusinessServiceQuery) an run it on ALSBConfigurationMBean to get ref object to osb artifact of your interest
Invoke getServiceDefinition on your ref object to get XML service
definition
Extract URI from XML service definition with XPath
Downside of this approach is that you are basically pooling configuration each time you want to check if anything has changed.
More information including JAVA/WLST examples can be found in Oracle Fusion Middleware Java API Reference for Oracle Service Bus
There is also a good blog post describing OSB customization with WLST ALSB/OSB customization using WLST
The information about services and all its properties can be obtained via Java API. The API documentation contains sample code, so you can get it up and running quite quickly, see the Querying resources paragraph when following the given link.
We use the API to read the service (both proxy and business) configuration and for simple management.
As long as you only read the properties you do not need to handle management sessions. Once you change the values, you need to start a session and activate it once you are done -- a very similar approach to Service bus console.
I am coding a MVC 5 internet application, and am wishing to use Hangfire for recurring tasks.
How can I setup Hangfire to use SQL Server storage without specifying this in the Startup.Auth ConfigureAuth(IAppBuilder app) function.
Here is a resource link for SQL Server configuration: http://docs.hangfire.io/en/latest/configuration/using-sql-server.html
This resource states that:
If you want to use Hangfire outside of web application, where OWIN
Startup class is not applicable, create an instance of the
SqlServerStorage manually and pass it to the JobStorage.Current static
property. Parameters are the same.
The example code is as follows:
JobStorage.Current = new SqlServerStorage("connection string or its name");
I have tried the following code (with my own connection string), yet the dashboard is not available. I have called the code above from a controller function.
Is there something that I have not done correct? How can I setup Hangfire to use SQL Server storage without using the Startup.Auth class?
Thanks in advance.
I think this is your problem:
I have called the code above from a controller function.
You should be setting this up once on application startup - either in the Configuration method of an OWIN Startup class (followed by an app.UseHangFireServer();), or in the Application_Start method of your Global.asax.cs if you really don't want to use OWIN. Either way, the line you're looking for is right there in the documentation you reference:
Hangfire.GlobalConfiguration.Configuration.UseSqlServerStorage(#"connection string or connection string name");
HOWEVER, as far as I know, if you want to use the dashboard you must configure that part via OWIN along with an authorization filter. See http://docs.hangfire.io/en/latest/configuration/using-dashboard.html
So really, I don't know if any downside of using the OWIN configuration for all of this. It's the more modern platform, and since you mention this is for an MVC5 app it's unlikely that you have legacy concerns.
We need to get certain information from PortletRequest in our Portal application. We do that using a utility method inside our Portlet Application. In this Utility method we access FacesContext.getCurrentInstance().getRequest() to get the PortletRequest. We access this Utility method in our DAO layer. We do not have access to request parameter here.
It works sometimes, but at times it gives me NullPointerException. I found a similar thread which explains about this. They have mentioned, if it is part of the same request, then you should get the Context. For me, it is part of the same request, but I'm not getting the context. Can you please help me.
If you are getting a null FaceContext from FacesContext.getCurrentInstance() then no FacesContext has been constructed for this Thread/Request.
Are the failing requests coming through a non-faces entry point? Such as an Event or Resource portlet request? If so there will be no FacesContext created.
Rather than relying on static methods and thread local storage to access data in you DAO you should consider extracting what you need from the PortletRequest, and passing it down your stack. It is bad practice to mix presentation layer artefacts such as the FaceContext or a PortletRequest with your DAO layer.
If your application is deployed in separate WAR/JAR files, it is likely that different classloaders are used. I had a similar problem, when I tried to access the FacesContext inside an hibernate HAR archive on JBOSS5. I came up with a successfull solution using reflection API. Take a look at this.
If you bundle your whole application into one EAR, you might be able to force the use of one classloader for the whole ear, but AFAIK that is application server specific.
Regards
I am using a SQL Server for ASP.Net session state. However, I am only able to retrieve the connection string at runtime and for that reason cannot store it in the web.config file. Usually it would be in:
<sessionState
mode="SQLServer"
sqlConnectionString="data source=127.0.0.1;user id=<username>;password=<strongpassword>"
cookieless="false"
timeout="20"
/>
How can I set that connection string at runtime? (i.e. after the web app spins up.)
Have you looked at doing it in the Application_Start event in Global.asax? This seems like the logical place to set something like that.
From MSDN's documentation:
Called when the first resource (such
as a page) in an ASP.NET application
is requested. The Application_Start
method is called only one time during
the life cycle of an application. You
can use this method to perform startup
tasks such as loading data into the
cache and initializing static values.
You should set only static data during
application start. Do not set any
instance data because it will be
available only to the first instance
of the HttpApplication class that is
created.
I would think you can set that string somewhere within System.Web.SessionState, hopefully that will help you get to the right place. Sorry I can't give a better answer, I'm still trying to figure it out myself. If I do, I'll let you know. GL