Emulex是融合网络解决方案领域的全球领导者,致力于为数据中心内的服务器、网络和存储设备提供企业级连接。
软件定义:软件是用户与硬件之间的接口界面。用户主要是通过软件与计算机进行交流。软件是计算机系统设计的重要依据。为了方便用户,为了使计算机系统具有较高的总体效用,在设计计算机系统时,必须全局考虑软件与硬件的结合,以及用户的要求和软件的要求。
数据库软件定义:用于数据管理的软件系统,具有信息存储、检索、修改、共享和保护的功能。目前流行的数据库软件有Access、Sybase、SQL server、ORACLE、Foxpro等,它们都属于关系型数据库软件。
软件和硬件是什么意思
硬件就是看的见的东西:比如:显示器,硬盘,键盘,之类的
软件就是机器上装的程序:比如:QQ,一些聊天工具,作图工具电脑及其内部的所有组件,都是我们能够实实在在地看到的东西或设备,如显示器,鼠标,键盘,机箱,机箱里面的CPU,主板,硬盘等,我们把这些设备都叫做硬件.一个电脑系统中只有硬件是不够的,因为它不能为我们做任何事情,只有在电脑系统中添加了相应的软件后,电脑才能发挥它巨大的作用,才能实现我们所要求的目的.所谓软件,就是安装或存储在电脑中的程序,有时这些软件也存储在外存储器上,如光盘或软盘上.我们所知道的软件有:幸福之家,Windows98等.
以通过一些例子,进一步理解软件,硬件的概念.比如:我们经常使用的音乐磁带,就这盒磁带本身来说,它是一个硬件,用来播放磁带的录音机也是一个硬件,而存储在磁带上的音乐就是软件.
软件可分为系统软件和应用软件,像Windows98这样的软件(也叫操作系统)就是系统软件,而像"幸福之家"这样的软件就是应用软件.
通过了解软件,硬件的概念,我们也就知道了它们之间的关系,那就是,硬件和软件是相互依存的,硬件为软件提供了物质基础,即软件离开了相应硬件支持,是无法发挥其作用的,而硬件只有有了软件的支持,才能使硬件有了用武之地.但是,并不是有了某种硬件就能运行所有的软件,也不是有了某个软件就能在所有的硬件上运行,这就是电脑中很普遍的兼容性问题.
平台化管理软件的定义?是什么意思?
软件功能落在不同的模块上,需要什么功能增加什么模块即可,所有模块均在一个平台上开发运行!模块间无缝衔接!
用友软件里面有个容差的概念,请问是什么意思
单笔容差:录入,默认为.06。修改税额超过容差时,系统提示超出容差范围,取消修改,恢复原税额。
整单容差:录入,默认为.36。保存单据超过合计容差时,系统提示,返回单据。
提示:
税额变动时,根据(无税金额×税率-税额)是否大于设置的容差数值进行判断。大于时,提示“输入的税额变化超过容差”;小于时,不需要提示。
单笔容差根据表体无税金额、税额、税率计算;整单容差根据无税金额合计、税额合计、表头税率计算。
若单据表体存在多种税率,则系统不进行整单容差控制。
软件开发是个什么概念?
1、软件开发是根据用户要求建造出软件系统或者系统中的软件部分的过程。
2、软件开发是一项包括需求捕捉、需求分析、设计、实现和测试的系统工程。
3、软件一般是用某种程序设计语言来实现的。通常采用软件开发工具可以进行开发。
4、软件分为系统软件和应用软件,并不只是包括可以在计算机上运行的程序,与这些程序相关的文件一般也被认为是软件的一部分。
5、软件设计思路和方法的一般过程,包括设计软件的功能和实现的算法和方法、软件的总体结构设计和模块设计、编程和调试、程序联调和测试以及编写、提交程序。
6、常见的软件开发语言:JAVA、C/C++/php/JSP/ASP/POWERBUILDER/DELPHI/.NET/C#/vb/等。与应用最关键的需要用到数据库,常见数据库:MySQL/SQLSERVER/ORACLE等。
什么是软件定义网络
话说最近网络虚拟化(Networking Virtualization,NV)和SDN真实热得发烫,先谈一下我个人的理解和看法。由于没有实际玩过相应的产品,所以也只是停留在理论阶段,而且尚在学习中,有些地方难以理解甚至理解错误,因此,特地来和大家交流一下。
早在2009年就出现了SDN(Software Defined Networking)的概念,但最近才开始被众人所关注,主要还是因为Google跳出来表态其内部数据中心所有网络都开始采用OpenFlow进行控制,将OpenFlow从原本仅是学术性的东西瞬间推到了商用领域。第二个劲爆的消息就是VMWare大手笔12.6个亿$收掉了网络虚拟化公司Nicira。
SDN只是一个理念,归根结底,她是要实现可编程网络,将原本封闭的网络设备控制面(Control Plane)完全拿到“盒子”外边,由集中的控制器来管理,而该控制器是完全开放的,因此你可以定义任何想实现的机制和协议。比如你不喜欢交换机/路由器自身所内置的TCP协议,希望通过编程的方式对其进行修改,甚至去掉它,完全由另一个控制协议取代也是可以的。正是因为这种开放性,使得网络的发展空间变为无限可能,换句话说,只有你想不到,没有你做不到。
那SDN为什么会和NV扯上关系呢?其实他们之间并没有因果关系,SDN不是为实现网络虚拟化而设计的,但正式因为SDN架构的先进性,使得网络虚拟化的任务也得以实现。很多人(包括我自己)在最初接触SDN的时候,甚至认为她就是NV,但实际上SDN的目光要远大得多,用句数学术语来说就是“NV包含于SDN,SDN包含NV”。
再来看看NV,为什么NV会如此火爆,归根结底还是因为云计算的崛起。服务器/存储虚拟化为云计算提供了基础架构支撑,也已经有成熟的产品和解决方案,但你会发现一个问题,即便如此,虚拟机的迁移依然不够灵活,例如VMWare vMotion可以做到VM在线迁移,EMC VPLEX可以做到双活站点,但虚拟机的网络(地址、策略、安全、VLAN、ACL等等)依然死死地与物理设备耦合在一起,即便虚拟机从一个子网成功地迁移到另一个子网,但你依然需要改变其IP地址,而这一过程,必然会有停机。另外,很多策略通常也是基于地址的,地址改了,策略有得改,所以依然是手动活,繁杂且易出错。所以说,要实现Full VM Migration,即不需要更改任何现有配置,把逻辑对象(比如IP地址)与物理网络设备去耦(decouple)才行。这是一个举例,总而言之,目的就是实现VM Migration Anywhere within the DataCenter non-disruptively,尤其是在云这样的多租户(Multi-tanency)环境里,为每一个租户提供完整的网络视图,实现真正的敏捷商务模型,才能吸引更多人投身于云计算。
SDN不是网络虚拟化的唯一做法,Network overly(mac in mac, ip in ip)的方式也是现在很多公司实际在使用的,比如Microsoft NVGRE、Cisco/VMWare VXLAN、Cisco OTV、Nicira STT等。事实上overly network似乎已经成为NV实现的标准做法,SDN模型下的NV实现目前更多的是在学术、研究领域。新技术总是伴随大量的竞争者,都想在此分一杯羹,甚至最后成为标准。好戏才刚刚上演,相信会越发精彩。
个人觉得这是一个非常有意思的话题,希望和大家交流心得,互相学习.
NV的目标就是如何呈现一个完全的网络给云环境中的每一个租户,租户可能会要求使用任何其希望使用的IP地址段,任何拓扑,当然更不希望在迁移至公共云的情况下需要更改其原本的IP地址,因为这意味着停机。所以,客户希望有一个安全且完全隔离的网络环境,保证不会与其他租户产生冲突。既然vMotion之类的功能能够让虚拟机在云中自由在线漂移,那网络是否也能随之漂移呢?这里简单介绍下微软的Hyper-v networking virtualization,到不是因为技术有多先进,只不过他的实现细节比较公开,而其它公司的具体做法相对封闭,难以举例。
其实微软的思路很简单,就是将原本虚拟机的二层Frame通过NVGRE再次封装到 IP packet中进行传输,使得交换机能够通过识别NVGRE的Key字段来判断数据包的最终目的地。这其实就是一个Network Overlay的做法,它将虚拟网络与物理网络进行了分离。试想,公司A和公司B都迁移到公有云且就那么巧,他们的一些虚拟机连接到了同一个物理交换机上,现在的问题是,他们各自的虚拟机原本使用的私有IP段是一样的,如果没有VLAN就会导致IP冲突。但现在看来,这已经不是问题,因为虚拟机之间的通信都要通过NVGRE的封装,而新的IP包在物理网络上传输时是走物理地址空间的,而物理地址空间是由云服务提供者所独占的,因此不存在IP冲突的情况。
总结一下就是,这里的网络虚拟化可以认为是IP地址虚拟化,将虚拟网络的IP与物理网络完全分离,这样做就可以避免IP冲突,跨子网在线迁移虚拟机的问题,微软的要求是:虚拟机可以在数据中心中任意移动,而客户不会有任何感觉,这种移动能力带来了极大的灵活性。
Software-defined networking (SDN) is an approach to computer networking which evolved from work done at UC Berkeley and Stanford University around 2008.[1] SDN allows network administrators to manage network services throughabstraction of lower level functionality. This is done by decoupling the system that makes decisions about where traffic is sent (the control plane) from the underlying systems that forwards traffic to the selected destination (the data plane). The inventors and vendors of these systems claim that this simplifies networking.[2]
SDN requires some method for the control plane to communicate with the data plane. One such mechanism, OpenFlow, is often misunderstood to be equivalent to SDN, but other mechanisms could also fit into the concept. The Open Networking Foundation was founded to promote SDN and OpenFlow, marketing the use of the term cloud computing before it became popular.
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One application of SDN is the infrastructure as a service (IaaS).
This extension means that SDN virtual networking combined with virtual compute (VMs) and virtual storage can emulate elastic resource allocation as if each such enterprise application was written like a Google or Facebook application. In the vast majority of these applications resource allocation is statically mapped in inter process communication (IPC). However if such mapping can be expanded or reduced to large (many cores) or small VMs the behavior would be much like one of the purpose built large Internet applications.
Other uses in the consolidated data-center include consolidation of spare capacity stranded in static partition of racks to pods. Pooling these spare capacities results in significant reduction of computing resources. Pooling the active resources increases average utilization.
The use of SDN distributed and global edge control also includes the ability to balance load on lots of links leading from the racks to the switching spine of the data-center. Without SDN this task is done using traditional link-state updates that update all locations upon change in any location. Distributed global SDN measurements may extend the cap on the scale of physical clusters. Other data-center uses being listed are distributed application load balancing, distributed fire-walls, and similar adaptations to original networking functions that arise from dynamic, any location or rack allocation of compute resources.
Other uses of SDN in enterprise or carrier managed network services (MNS) address the traditional and geo-distributed campus network. These environments were always challenged by the complexities of moves-adds-changes, mergers & acquisitions, and movement of users. Based on SDN principles, it expected that these identity and policy management challenges could be addressed using global definitions and decoupled from the physical interfaces of the network infrastructure. In place infrastructure on the other hand of potentially thousands of switches and routers can remain intact.
It has been noted that this "overlay" approach raises a high likelihood of inefficiency and low performance by ignoring the characteristics of the underlying infrastructure. Hence, carriers have identified the gaps in overlays and asked for them to be filled by SDN solutions that take traffic, topology, and equipment into account.[7]
SDN deployment models[edit]
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Symmetric vs asymmetric
In an asymmetric model, SDN global information is centralized as much as possible, and edge driving is distributed as much as possible. The considerations behind such an approach are clear, centralization makes global consolidation a lot easier, and distribution lowers SDN traffic aggregation-encapsulation pressures. This model however raises questions regarding the exact relationships between these very different types of SDN elements as far as coherency, scale-out simplicity, and multi-location high-availability, questions which do not come up when using traditional AS based networking models. In a Symmetrically distributed SDN model an effort is applied to increase global information distribution ability, and SDN aggregation performance ability so that the SDN elements are basically one type of component. A group of such elements can form an SDN overlay as long as there is network reachability among any subset.
Floodless vs flood-based
In a flood-based model, a significant amount of the global information sharing is achieved using well known broadcast and multicast mechanisms. This can help make SDN models more Symmetric and it leverages existing transparent bridging principles encapsulated dynamically in order to achieve global awareness and identity learning. One of the downsides of this approach is that as more locations are added, the load per location increases, which degrades scalability. In a FloodLess model, all forwarding is based on global exact match, which is typically achieved using Distributed Hashing and Distributed Caching of SDN lookup tables.
Host-based vs Network-centric
In a host-based model an assumption is made regarding use of SDN in data-centers with lots of virtual machines moving to enable elasticity. Under this assumption the SDN encapsulation processing is already done at the host HyperVisor on behalf of the local virtual machines. This design reduces SDN edge traffic pressures and uses "free" processing based on each host spare core capacity. In a NetworkCentric design a clearer demarcation is made between network edge and end points. Such an SDN edge is associated with the access of Top of Rack device and outside the host endpoints. This is a more traditional approach to networking that does not count on end-points to perform any routing function.
Some of the lines between these design models may not be completely sharp. For example in data-centers using compute fabrics "Big" hosts with lots of CPU cards perform also some of the TopOfRack access functions and can concentrate SDN Edge functions on behalf of all the CPU cards in a chassis. This would be both HostBased and NetworkCentric design. There may also be dependency between these design variants, for example a HostBased implementation will typically mandate an Asymmetric centralized Lookup or Orchestration service to help organize a large distribution. Symmetric and FloodLess implementation model would typically mandate in-network SDN aggregation to enable lookup distribution to a reasonable amount of Edge points. Such concentration relies on local OpenFlow interfaces in order to sustain traffic encapsulation pressures.[5] [6]
MAYA软件中刷权重是什么意思啊,麻烦解释下这个概念
就拿肌肉来吧,权重说白了也就是肌肉随着骨骼动的时候不发生扭曲、拉扯.或者说是让肌肉随着你自己的意思跟着骨骼运动弯曲.
蒙皮过后,肌肉权重就按系统自动分配到了每节骨骼上,这里就需要你来调试了,比如说人的胳膊,在刷权重之前,肘关节弯曲的时候会很,,乱七八糟的.通过刷权重来使符合自然的人体运动规律,恩,应该就是这个意思吧,多做做就明白了.
这是多年来我自己对权重的一点理解,不足之处多见谅.
软件语言??是什么意思?
软件语言(Software Language)是用于书写计算机软件的语言。它主要包括需求定义语言、功能性语言、设计性语言、程序设计语言以及文档语言等。
需求定义语言用以书写软件需求定义,软件需求定义是软件功能需求和非功能需求的定义性描述。软件功能需求刻画“做什么”,软件非功能需求刻画诸如功能性限制、设计限制、环境描述、数据预通信规程以及项目管理等。需求定义语言经历了从非形式的自然语言到半形式化语言以及形式化语言的发展,迄今半形式化的需求定义语言已经有很大的发展,已逐步用于软件工程的实践。
设计性语言用以书写软件设计规约。软件设计规约是软件设计的严格而完整的陈述。一方面,它是软件功能规约的算法性细化,刻画了软件“如何做”的内部算法;另一方面,它又是软件实现的依据从。从细化程度来看,有总体设计规约与详细设计规约之分。前者刻画设计的总计框架;后者刻画详尽细节。
实现性语言,即一般的程序设计语言,用于计算机程序、处理对象和规则的描述。程序设计语言有高级语言和低级语言之分。
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