SOW Maintenance

Applications that store topics in the SOW must consider the ongoing storage needs and file management for the SOW.

There are two aspects to SOW maintenance:

1. Ensuring that the host system has enough capacity to efficiently store and manage the topics in the SOW. Capacity planning guidelines are discussed in the Capacity Planning section in the operations section of this guide.

2. Setting and implementing a data retention policy for the contents of each topic in the SOW.

The data retention policy for a topic in the SOW is determined by the needs of your application.

Consider the following questions:

• Does the topic have a data set that tends to stay at a consistent size? If so, there may be no need to explicitly manage data retention. Many AMPS applications have topics that fall into this category.

  For example, an application that uses a SOW topic to track the current price of a specific set of ticker symbols has little need to set a data retention policy. The SOW will always contain the same number of records (one for each ticker symbol), and those records will always contain data of a consistent size. The application may choose to remove a record when a symbol is removed from the set, but otherwise rely on publishers to keep the data current.

• Is the data only valid for a specific period of time after the data is published? If so, SOW expiration may be a good way to manage the SOW.

  For example, an application that needs to ensure that quotes are removed from the system after 10 minutes from the time the quote is published could use SOW expiration to remove records after 10 minutes.

• Is the data valid until a certain condition becomes true? If so, having the application remove records from the SOW or using AMPS actions may be a good way to manage the SOW.

  For example, an application that needs to clear the state of the SOW every 24 hours during a maintenance window could use an action to remove those records. An application that can determine when a record is no longer needed can remove the record immediately, which means that the topic only contains data that the application needs at any given time.

Regardless of the approach an application takes, 60East recommends that every application that uses a SOW consider capacity and explicitly consider the data retention needs of each topic and the application.