1# commonlibrary<a name="EN-US_TOPIC_0000001092539399"></a> 2 3 4## Introduction<a name="section11660541593"></a> 5 6The **commonlibrary** subsystem provides common enhanced APIs for development in C, C++ and JS. 7 8**c_utils** 9 10- Enhanced APIs for operations related to files, paths, and strings 11- APIs related to the read-write lock, semaphore, timer, thread, and thread pool 12- APIs related to the security data container and data serialization 13- Error codes for each subsystem 14- Safe functions in C 15 16**ets_utils** 17 18- JSAPIs for operation of URI, URL and xml 19- JSAPIs for character encoder and decoder 20- JSAPIs for operation of process 21- Multithreading ability in JS 22 23**utils_lite** 24 25- Hardware Abstraction Layer (HAL) APIs for performing operations on standard files 26- APIs for internal functions, such as the timer 27 28## Directory Structure<a name="section17271017133915"></a> 29 30``` 31/commonlibrary 32 ├── c_utils # Enhanced basic C/C++ library for developers 33 ├── ets_utils # Enhanced basic JS library for developers 34 └── utils_lite # Basic tools for liteOS, including C and JS. 35``` 36 37## Repositories Involved<a name="section1249817110914"></a> 38 39**commonlibrary subsystem** 40 41[commonlibrary\_c\_utils](https://gitee.com/openharmony/commonlibrary_c_utils) 42 43[commonlibrary\_ets\_utils](https://gitee.com/openharmony/commonlibrary_ets_utils) 44 45[commonlibrary\_utils\_lite](https://gitee.com/openharmony/commonlibrary_utils_lite) 46