Introduction to Coherence

Coherence is a high-performance, distributed in memory data grid (IMDG) developed and supported by Oracle. It aims to provide high-speed data access and processing capabilities for large-scale, highly concurrent applications. Coherence supports multiple programming languages such as Java,. NET, and C++, and provides flexible deployment options, including single node, multi node, and cloud environments. Coherence was founded in 2000 by Tangosol Corporation, which was founded by Cameron Purdy, Steve Harris, and Gene Gleyzer. They later sold the company to Oracle in 2007. Coherence is one of Oracle's products, providing distributed data management and caching solutions as part of its cloud platform and application service portfolio. Coherence is suitable for enterprise level applications that require fast access and processing of large amounts of data. It can be used in various scenarios, such as real-time trading systems in the financial industry, billing systems in the telecommunications industry, and online shopping systems in e-commerce. Coherence also provides various functions, such as data cache, data distribution and replication, Transaction processing, query and calculation, which can meet different needs of applications. The advantages of Coherence are mainly reflected in the following aspects: 1. High performance: Coherence uses memory as the main storage medium, resulting in extremely fast data access speed. And improve the availability and reliability of data through data distribution and replication. 2. Scalability: Coherence supports horizontal scaling and can easily add new nodes to the cluster to handle larger data and request loads. 3. Reliability: Coherence provides data replication and fault recovery mechanisms, ensuring the reliability and high availability of data. When a node fails, Coherence can automatically migrate Data migration to other available nodes to ensure the normal operation of the system. 4. Flexibility: Coherence provides rich APIs and functions that can be customized and developed according to the needs of the application. It can also be integrated with other Oracle products and technologies, such as Oracle Database, WebLogic Server, etc. However, Coherence also has some drawbacks: 1. The Learning curve is steep: because Coherence is a complex distributed system, first-time users need to spend some time and energy to learn and understand its concept, architecture and use methods. 2. Requires a large amount of memory resources: Coherence stores data in memory, so for large-scale datasets, sufficient memory resources are needed to ensure high-performance operation. 3. High maintenance difficulty: Distributed systems themselves increase the complexity of deployment and maintenance, and developers who are not familiar with distributed systems may need to face some challenges. Coherence's technical principles mainly include data fragmentation and replication, consistent hash algorithm, distributed query and Transaction processing processing. It improves the availability and reliability of data by dividing it into multiple fragments and copying them to multiple nodes. The consistency hash algorithm is used to determine the distribution of data between nodes, ensuring load balancing and fault recovery of data. Distributed query and Transaction processing capabilities allow applications to manipulate data in a manner similar to a relational database. In terms of performance analysis, Coherence has excellent performance. Due to data being stored in memory and improved availability and reliability through data replication and distribution, Coherence can achieve extremely fast data access and processing speed. In addition, due to its ability to scale horizontally, the load can be distributed across multiple nodes to further improve the system's concurrent processing capability. The official website of Coherence is: https://www.oracle.com/middleware/technologies/coherence.html In summary, Coherence is a high-performance distributed memory data grid suitable for large-scale, highly concurrent enterprise applications. It has the advantages of high performance, scalability, and reliability, and can meet the data access and processing needs in different scenarios. However, Coherence also faces the shortcomings of steep Learning curve and high requirements for memory resources. By understanding its technical principles and performance analysis, the value and applicability of Coherence in practical projects can be better evaluated and applied.