The redesign of the administrator console for the Streams 4.0Â release allows streams users to quickly determine problems areas in the domain. They can act rapidly to resolve these issues, as well as perform general tasks like creating instances, and monitoring streams objects. This article is a follow-up to the “Navigating in the Domain Console” article and explains how to create and manage instances in the domain.
To follow along yourself and try out the instance management functionality in the domain console, log in to your domain console. The default url is:
If you have forgotten the url for your streams domain console, you can always retrieve it by issuing this streamtool command:
streamtool geturl -d <domain_name>
Once logged in you will see the domain monitoring view of the console. At the top of the console is a status navigation control with all of the various streams objects represented. Hover over the “Instances” button (mine currently displays zero instances in the domain) and a dialog appears:
The table on the left above displays all of the instances in the domain. No instances have been created in this domain. To the right of the table, several options are listed. Since no instances have been created the only option available is “Manage Instances”.
Select this option to display the Instance Management page. The domain monitoring page is now hidden, and the new page slides into view.
The buttons at the top of the instance management page (from left to right) are used to add an instance, remove an instance, edit an instance’s properties and to start or stop an instance. Let’s make our first instance!
Adding an Instance to the Domain
Click on the “+” button to launch this dialog:
Name your instance and select the Number of Standby Services for High Availability, then click the “Next” button. To create a truly highly available instance, select at least 2 standby services.
The next screen shows two tabs – the first can be used to automatically assign resources for the instance and the second is to manually assign resources to the instance based on resource name or IP address. Use the first if you would like the streams infrastructure to assign a resource based on resource availability within the domain.
I’m going to assign 1 resource to this instance. This resource does not have a tag associated with it and I will not constrain this resource only to this instance. Below is what my screen looks like right before I click the “Add” button. Notice how the information at the bottom shows that I currently have 0 resources assigned to this instance.
Once I click the “Add” button at the right of the top row, the status at the bottom changes. I also checked the “Start the instance” button so the instance will be started as soon as it has been created:
Now click the “Finish” button. The instance will be created, and after a short time the instance will be started. Your table will contain the name of the instance you just created, along with a symbol indicating the status of the instance.
The popups at the right bottom of the screen relay status information during instance creation and start. While the instance is starting some detailed information about the instance will be displayed in the middle of the page.
Editing an Instance
With the first instance you created selected in the table (denoted by the light blue background) the buttons at the top are now active. From here the instance can be removed, it’s properties edited, or it can be stopped. For the instance I just created I’d like to add some more standby services. I click the “Edit” button (the one that looks like a pencil) and the “Add Instance” dialog opens. All of the original characteristics of the instance can be modified using this dialog other than the instance name. I will modify the number of standby services to 3 by selecting “Other: Number of backups” and entering the number “3”. Clicking “Next” and then “Finish” updates my instance.
Modifying Instance Properties
Now let’s look at all the properties of the instance we created and change a value of a property.
With the instance selected in the left table, click on the “Show Details” link next to the word “Properties” in the middle column:
All of the instance’s properties will be displayed in a tree format, depending on what the property relates to. Browse through the properties to get an idea of which properties are available to modify. Once a property has been selected an information area is displayed below the selected property which explains what the property represents and also the meaning of the symbols. I selected the view –> initialJvmSize property. The image below shows the information about this property:
Let’s modify the value of this property. Double click in the right column of the “initialJvmSize” row to make the field editable and modify the value. Since the minimum value is 512 by default, I’d like to allocate a higher initial value for this property and will set it to 1024. Once I enter the value of “1024” and tab away from the row I’m editing, the value is updated as is the information area below. It now reads: The pending value of 1024 will take affect after the instance is restarted.
Note: Modifying a property on an instance that is stopped will always take effect immediately.
Adding an Application Environment Variable
The last thing to discuss about the instance management page is setting, removing and modifying application environment variables for an instance. Currently we have no variables set for this instance. Click the “Add a variable …” link under the “Application Environment Variables”‘ section for our lone instance. This dialog appears which I’ve added my variable name and value to.
After I click the “OK” button, the “Application Environment Variables” area is refreshed and informs me that one is set for this instance. If I wish to remove that variable, I can click the “Remove a variable … ” link. A dialog would appear allowing me to select the variable to remove.
To edit the value of an Application Environment variable, click the “Show Details” link. Once the table appears with the variables, I clicked in the right part of the row where the value of my variable is so I can edit it. The image below shows the row being edited:
The instance management page is used to create instances, start and stop them, edit their properties and add application environment variables to an instance.
This page is useful if many instances are being created at once, or modifications are necessary for an instance. Another way to create an instance is available in the “Domain Tree” from the domain monitor page.
To navigate back to the Domain monitor page, click the “Close” button on the Instance Management page.
Once you are back at the domain monitor page, hover over the left most button (the one with the three horizontal lines) to the left of “RESOURCES”. The domain tree appears. In the picture below I have selected the “Instances” node and the available options for instances appear. To create a new instance, select the “Make Instance” link.
This article focused on creating and managing instances and how to navigate to the instance management page. Other articles will discuss managing resources and assigning and viewing permissions of streams objects. Please feel free to leave feedback on the usefulness of the instance management page, as well as suggestions on improving this page or requests for additional functionality.