How to read IMS data

In today’s data-driven world, efficiently analyzing data is a critical skill that can provide valuable insights and improve decision-making processes. One type of data structure commonly used in mainframe environments is IMS (Information Management System) data. IMS, developed by IBM, is a hierarchical database management system that organizes data in a tree-like structure. In this article, we will explore the basics of reading IMS data and understand some key concepts associated with it.

Understanding IMS Data Structure:

IMS data is organized in a hierarchical structure, with records grouped into segments. Each segment contains one or more fields that store specific data. The hierarchy starts with a root segment, which branches out into child segments and further extends into more levels of segments, creating a tree-like structure. This hierarchical layout helps in organizing and accessing data efficiently.

Navigating through the Hierarchy:

To efficiently read IMS data, it is essential to understand how to navigate through the hierarchy. IMS provides a set of pointers or codes that indicate the relationship between segments. One such pointer is the SSA (Segment Search Argument), which identifies a specific segment within the hierarchy. By using the SSA, you can easily locate the desired segment or move up or down within the hierarchy.

Reading Segment Data:

Once you have located the desired segment, you can read the data stored within it. IMS segments are composed of fields that store specific information such as names, addresses, or any other relevant data. Each field has a name, length, and type associated with it. By identifying the field names and their corresponding offsets within the segment, you can read the data present in those fields.

Data Relationships:

IMS data is known for its hierarchical relationships among segments. These relationships can be of three types: parent-child, linked, or sequential. In a parent-child relationship, a parent segment is associated with one or more child segments. Linked relationships connect segments that share a common key, providing easy access between them. Sequential relationships are similar to linked relationships but are used when the order of the segments is significant.

Indexing:

To improve the efficiency of data retrieval, IMS uses indexing techniques. Indexing involves creating an index structure that allows you to quickly access specific segments based on a key value. By using indexes, you can bypass the need to traverse the entire hierarchy, resulting in faster data retrieval.

Access Methods:

IMS supports various access methods to retrieve data from its hierarchical structure. One commonly used access method is the Dynamic Sequential (DSECT) access method, which allows sequential access to segments based on a specific criterion. Another method is the Hierarchical Direct (HDAM) access, which provides direct access to a segment based on a unique key. By understanding these access methods, you can choose the most appropriate one based on your specific requirements.

Tools and Languages:

Several programming languages and tools are available to read and manipulate IMS data. These include COBOL, PL/I, Assembler, and IMS tools like IMS DB/DC and IMS TM. Depending on your familiarity and requirements, you can choose the suitable tool or language to effectively read IMS data.

In conclusion, understanding how to read IMS data is crucial for efficiently analyzing information stored in this hierarchical database management system. By comprehending the data structure, navigating the hierarchy, and using appropriate tools and languages, you can effectively access and extract valuable insights from IMS data. With the increasing reliance on data analytics, mastering the skills to read IMS data can prove to be an invaluable asset in today’s rapidly evolving technological landscape.