主题目录

• Creating a Distributed Cache Cluster

  Creating a Distributed Cache Cluster

  Content Type
  Exercise

  Duration
  20m

  Level
  Intermediate

  See how InterSystems IRIS® data platform scales for user volume by using distributed caching across application servers and leveraging the Enterprise Cache Protocol (ECP). In this exercise, you will configure ECP on several InterSystems IRIS instances, then test the distributed cache cluster.

  Learning Objectives

  • Configure an instance as a data server and enable the ECP service, configure connection options, and create a database. The data server contains a namespace and database where data is stored.
  • Configure two more instances as application servers, enable ECP, and connect to the remote database on the data server.

  Prerequisites

  None
• Start the Exercise

  Start the Exercise

  For this exercise, InterSystems IRIS instances in the VM were deployed using Docker and are connected in a Docker network. In real deployments, the instances are probably deployed on separate network-connected systems to scale for user volume. For demonstration purposes, this exercise uses a single operating system and a Docker network.

  Launch the VM to get started:

  •  You must be logged in to launch an InterSystems IRIS instance.

    • Log in with your existing account.
    • Don't have an InterSystems account? Create a new account.
  • Set up your VM

    1. Once your VM has launched, click the URL in the launcher to open it in a new window.
    2. If needed, log in to the VM using the credentials provided in the launcher.
    3. Click the Fit to Window icon in the toolbar at the top to enlarge the default display for your VM. This also ensures your full screen is visible and nothing is cut off.

    Note:

    You can also recreate this ECP setup on your own system using your own InterSystems IRIS instances and network, adapting the instructions for your own system. For example, you will need to use your own server IP addresses and ports.
  • Enable the ECP service

    Enable the ECP service on the InterSystems IRIS instance that will act as the ECP data server.

    1. Open the Management Portal for the iris-data-server instance in your browser by opening Google Chrome and following the link in the bookmark bar.
    2. Log in to the Management Portal using these credentials:
       • Username: tech
       • Password: demo7
    3. Go to the Services page (System Administration > Security > Services).
    4. Select %Service_ECP. On the Edit Service page, select Service Enabled and click Save.

    You have now enabled ECP on your data server instance. There are just a few more steps to finish the setup for the data server and the two application servers.

  • Configure the data server

    On the system that will be your data server, you will increase the number of allowed application servers from the default of one, then create a new database for your application servers to connect to.

    1. In the Management Portal for iris-data-server, go to the ECP Settings page (System Administration > Configuration > Connectivity > ECP Settings).
    2. In the section This System as an ECP Data Server, set the maximum number of application servers to 2 and click Save.
    3. Restart the instance:
    1. Open a Terminal session by clicking the Terminal icon in the left navigation bar.
    2. Run docker stop iris-data-server.
    3. Run docker start iris-data-server.
    4. Once the instance has restarted, create a new database:
       1. In the data server Management Portal, go to the Local Databases page (System Administration > Configuration > System Configuration > Local Databases).
       2. Click Create New Database.
       3. Enter ECPDB as the name for the new database.
       4. Enter /usr/irissys/mgr/ECPDB as the database directory.
       5. Click Next, then Finish.

    You have created your new database, and your data server is ready. In the next sections, you will set up the two application servers and configure them to communicate with the data server.

  • Configure the application servers

    Next, you will set up your other two instances as application servers, defining an ECP connection to the data server from each.

    Note:

    If you are following along on your own system, you need your InterSystems IRIS instances to be network-connected.

    1. Log in to the Management Portal of an application server and go to the ECP Settings page (System Administration > Configuration > Connectivity > ECP Settings).
    2. Click Data Servers, then Add Server.
    3. Fill in the required information:
       • Server Name: data-server
       • Host DNS Name or IP Address: iris-data-server
       • IP Port: 1972
    4. Click Save.
       Your data server now appears in the list.
    5. Click Change Status on the new entry in the list. Change the status to Normal, then click Save.
    6. Repeat steps 1-5 on the second application server.
  • Create namespaces and remote databases

    Now that you have configured your application servers to connect to your data server, you will create a namespace on each application server. Instead of containing a local database, it will be mapped to a remote database—namely, the ECPDB database on the data server that you created in the previous task.

    1. In the Management Portal of an application server, go to the Namespaces page (System Administration > Configuration > System Configuration > Namespaces).
    2. Click Create New Namespace.
    3. Enter ECPDB as the name of the namespace.
    4. Select Remote Database as the default database for globals in this namespace, then click Create New Database. This opens the Create Remote Database window.
    5. Fill in the required information:
       • Remote Server: Use the drop-down menu to select the server name you gave the data server in the previous task.
       • Remote Directory: Select the directory containing the ECPDB database on the data server.
       • Database Name: Enter a name; this can be the same as its name on the data server (ECPDB in this example) or something else.
    6. Click Finish. The window closes, and you are returned to the New Namespace page.
    7. Select Remote Database as the default database for routines in this namespace. You should now be able to select the new database you just created from the Select an existing database for Routines drop-down menu.
    8. Clear the Enable namespace for interoperability productions checkbox.
    9. Click Save. The new namespace now appears on the list.
    10. Repeat steps 1-9 on your second application server.

    Setup is now complete; you have successfully created a cluster with one data server and two application servers. In the next task, you will test the connections to make sure all three instances are communicating correctly.

  • Test the setup

    Now that you have enabled the ECP service and set up two application servers with namespaces pointing to the database on the data server, let's do a quick test to make sure that the three systems are communicating with each other. To accomplish this, you will set a simple global on one application server, then read and change it on the second application server.

    1. Open an Ubuntu terminal using the icon in the left navigation bar.
    2. Open the InterSystems Terminal for an application server using this command:

       docker exec -it iris-app-1 iris terminal iris

    3. On one application server, open the InterSystems Terminal and change to the namespace that you created in the previous task. In this example, the namespace is ECPDB, so you would enter:
       Begin code.

       USER>set $namespace = "ECPDB"
       ECPDB>

       End code.
    4. Create a global by giving it a value:

       ECPDB> set ^MyGlobal = "My Value"

    5. Leave the InterSystems Terminal with the command halt.
    6. Open the InterSystems Terminal for the second application server, using this command:

       docker exec -it iris-app-2 iris terminal iris

    7. Change to the ECPDB namespace:

       USER>set $namespace = "ECPDB"
       ECPDB>

    8. Write the value of the global: Begin code.

       ECPDB> write ^MyGlobal
       My Value

       End code.

    By accessing the same global variable from both application servers, you can see that they are communicating properly with the data server. When you used an application server to create a global variable, the global was created on the remote database on the data server. The second application server was able to read the variable because it has access to the same remote database.

    The mechanism is the same regardless of whether a single Terminal user manually sets and reads a global, or hundreds of application users execute thousands of database operations per second through a dozen application servers. ECP ensures that the data is kept in sync and guarantees transactional consistency for all users’ interactions with the system.

• What's next?

  What's next?

  In this exercise, you used many default settings; in a production system, you may want to configure server or security settings differently.

  To learn more about using distributed caching and ECP with InterSystems IRIS, see the following resources:

  • Read about automated deployment methods for clusters (documentation, 2m).
  • Learn more about creating a data server and setting available options (documentation, 2m).
  • See how to use a mirrored pair within a cached cluster (documentation, 5m).
  • Learn more about deployment options (learning path, 3h 30m).

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