?Hong Cai

Dr.Hong Cai is CTO of Cloud Computing at ZTE Cloud&IT Business Unit.He works with different teams to define the roadmap for the ZTE Cloud&IT product family.Before joining ZTE in 2012，he worked at IBM for nearly 15 years.There，he focused on cloud computing and service computing.He is also very active in academia，serving on the editorial boards of IJWSR，IJCAC and IEEE Transactions on Service Computing.He has served approximately 20 IEEE international conferences as workshop chair or program committee member.He has published more than 50 journal or conferencepapers and co-authored thebook Services Computing.He has filed more than 10 patents and given numerous keynote speeches and public talks at conferences and universities.In 1997，he received his PhD degreefrom Tsinghua University，China.

I n the last five years，great progresshas been made in cloud computing，especially in virtualization，standardization，and automation.This has resulted in numerous cloud services，such as Infrastructure as a Service，Platform as a Service，and Software as a Service.Many cloud technologies have matured and have been commercialized.However，issues such as information security，mobility，energy efficiency，and infrastructure optimization are becoming more serious.The key causes of these issues are increased scale of data centers，convergence of IT and CT，increased user concern about information security，and increased opex instead of capex.

For this special issue of ZTECommunications，researchers fromindustry and academia were called to submit articles detailing the latest progress on cloud computing.

The first paper，“Software-Defined Data Center，”by Ali et al.，gives an overview of key technologies and standardization of SDDC as well as challenges associated with it.The paper points out that a unified control plane allows rich resource abstractions to enable orchestration purpose fit systems and/or providing programmable infrastructures to enable dynamic optimization in response to business requirements.”

In their paper“Computation Partitioning in Mobile Cloud Computing:A Survey，”Yang et al.address the issue of computation partitioning in mobile cloud.This involves partitioning the execution of applications between the mobile side and cloud side so that the execution cost is minimized.The authors survey computation partitioningin mobilecloud computing.

In the paper“MapReduce in the Cloud:Data Location Aware VM Scheduling，”Nguyen el al.see thechallenge of MapReduce efficiency in the cloud and develop a distributed cache systemand virtual machine scheduler.They show that their prototype can improveperformance significantly when running different applications.

The paper“Preventing Data Leakage in a Cloud Environment，”by Cang et al.，dealswith the customer information security and avoidance of unauthorized data access in practical multiparty clouds.The authors survey techniques for preventing dataleakages，and thesetechniquescan beused in threetrust models.

In the next paper，“CPPL:A New Chunk-Based Proportional-Power Layout with Fast Recovery，”by Yin et al，the authors suggest that the size and number of data centers and cloud storage systems are dramatically increasing，and this，in turn，is dramatically increasing energy consumption and disk failures in emerging facilities.The authors propose a new chunk-based power-proportional layout called CPPL to addresstheseproblems.

In the last paper，“Virtualization of Network and Service Functions:Impact on ICT Transformation and Standardization，”Khasnabish et al.review trends in the virtualization of network/service functions.They also discuss standardization of and required management and orchestration of thesefunctions.

In thisspecial issue，it isour intention toinformthereader of state-of-the-art research and technology on current cloud computing topics and bring to attention of thecloud computingcommunity problemsthat must beinvestigated.

This special issue would not be possible without the help provided by many.We would like to thank all the authors for their contributions and all reviewers for their efforts and dedication.We also want to thank the editorial office of ZTE Communications for their support.