云计算在业务上的应用领域不断扩展，今天看到一篇对 Eris软件主管 Scott Morehouse的采访：

采访中，主要谈论了一下几点内容：（我将采访中几个重要问题转帖到这里）

给出关键字：SaaS, Collaborative environment, Multi-tenancy, Web-centric system, Security, Cloud

• How the cloud is enabling more collaboration around GIS data
• The cost and complexity in setting up on-site GIS solutions, vs. using cloud based or on-demand solutions
• The opportunity for “mashups” where users combine their on-site data with cloud-based data
• Opportunities created by Azure virtual machines and database instances

Robert: You’ve talked about the underpinnings moving from client/server to a web-based modality, and now leveraging cloud computing. How do you see cloud providing benefits for GIS?

Scott: There are a number of different dimensions that make cloud interesting to us and our users. First is the simple fact that information systems have been moving from a client/server pattern to a web-centered pattern. By that I mean that even intranet or internal systems within an organization are being built around a web programming pattern and around a web style of user interactions.

Building a web-style information system implies an easy-to-use, browser-based modality that is stateless and uses a certain programming pattern. It implies making the information available to devices like iPhones and tablets as well as to work stations. It implies a certain style of documentation and leveraging a community of people for a more collaborative environment.

People are very interested in building applications that work that way, because that’s the highest style of technology that they’re used to. Nobody works with command prompts anymore except for system administrators and developers.

Another trend is the complexity of building and managing a computing infrastructure for an organization or even for yourself. It’s really a difficult process to create the right infrastructure for hard drives, CPU cores, network connectivity, security, software patches, and so forth. So the notion of being able to grant or tie into a hosted infrastructure rather than having to build and maintain your own is very attractive to our users. They just want to turn a switch and get a new server that they can deploy a workload to.

A third thing is the ability to combine and mash up functionality and information that comes from other places. Users like to be able to take our case maps and data that others have created, and use them together in their own applications.

Robert: With SaaS applications, you want multi-tenancy and for each customer’s data set to be completely isolated. That’s sometimes true with GIS, but at other times you want to share and use community data. How does the cloud facilitate that?

Scott: The cloud facilitates the sharing of information in a couple of ways. One is that web-style system architecture makes information accessible through services. The notion that information is accessible through RESTful services or web-style interfaces really reduces the problems of getting at information. You’re not having to ETL data from one database to another or these types of things.

In that context, you have to be clear as to what information is private, what information is semi-private, and what information is public. I think there’s an implication that if information is easily accessible through a web-style interface, it also has to be public information. That’s not necessarily the case, and we can put security around information in that context.

I think the question of whether a system is based on a multi-tenant architecture or whether it’s based on having actual instances per user is kind of a fine point of implementation.

SQL Azure is multi-tenant, but there are individual database instances within that. Some people can own and control their own database container, but the system is optimized in such a way that it scales and has other attributes that multi-tenant applications give you. We see a combination of services that are implemented in a multi-tenant style and applications that are instance-per-organization style.

In the context of SharePoint, for example, there’s a role for both a multi-tenant approach, for sharing documents and collaborating on them, as well as for allowing people to rent their own SharePoint instance in a hosted or cloud environment.

Robert: Esri itself has a bit of a hybrid model, where you host your own servers but you also use Amazon and Windows Azure. Can you talk a little bit about your architecture and how you decide what to keep in house and what to host in the cloud?

Scott: Our fundamental architecture is web-centric, meaning that we’ve been working to expose maps and geographic information through open, web-accessible interfaces, primarily REST and JSON, but also SOAP and some other types. We’ve engineered our front end as clients to these services, so this web-centric system architecture can be deployed within an enterprise entirely, but it’s also well suited to running on the Internet. It’s also well suited to having elements of it, namely some of these services, actually hosted in a cloud infrastructure.

Since everything is a service, it really doesn’t matter whether the service is running on physical hardware that’s connected to your LAN or on virtual hardware that’s physically located in an Amazon or Azure data center. We just make practical decisions about which aspects of the system make sense to run in our customer’s data center, which services should run in the Azure cloud environment, and which ones should run in Amazon’s cloud. We look at requirements such as what functionality is most efficiently implemented in which infrastructure and which environments meet the security and access requirements.

Robert: How do you see other enterprises using hybrid models where they may keep a large number of servers and applications on site for the foreseeable future, but consume cloud services like those that Esri provides?

Scott: It’s not necessarily the case that to take advantage of cloud computing, you need to rewrite or move all of your applications from an enterprise-centric architecture to a cloud-centric architecture. It’s certainly possible to build on-premises enterprise applications that combine information coming from your enterprise systems with data feeds, information, and functionality that are coming through a subscription to a cloud service.

We’re seeing lots of mash up patterns where people combine geographic information from our hosted services with their enterprise information and even build their enterprise systems using on-premises web sites or thick-client applications.

http://datasearch.ruc.edu.cn/~boliangfeng/blog/?p=834