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To help illustrate how to configure auto update, here s a simple configuration example:

By default, the set and get accessors have the same accessibility as the indexer or property of which they are a part. For example, if the property is declared public, then by default the get and set accessors are also public. It is possible, however, to give set or get its own access modifier, such as private. In all cases, the access modifier for an accessor must be more restrictive then the access specification of its property or indexer. There are a number of reasons why you may want to restrict the accessibility of an accessor. For example, you might want to let anyone obtain the value of a property, but allow only members of its class to set the property. To do this, declare the set accessor as private. For example, here is a property called MyProp that has its set accessor specified as private.

More generally the polarization is elliptical. Elliptical polarization results when the electric field oscillation has two orthogonal linear components linked by a constant phase relation, as shown in Figure 28.6. The loss of a device exhibiting PDL may take maximum and minimum values when the incident light is elliptically polarized.

This is the iterator for MyClass. Notice that it implicitly implements the GetEnumerator( ) method defined by IEnumerable. Now, look at the body of the method. It contains a foreach loop that returns the elements in chrs. It does this through the use of a yield return statement. The yield return statement returns the next object in the collection, which in this case is the next character in chrs. This feature enables mc (a MyClass object) to be used within the foreach loop inside Main( ). The term yield is a contextual keyword in the C# language. This means that it has special meaning only inside an iterator block. Outside of an iterator, yield can be used like any other identifier. One important point to understand is that an iterator does not need to be backed by an array or other type of collection. It simply must return the next element in a group of elements. This means the elements can be dynamically constructed using an algorithm. For example, here is a version of the previous program that returns all uppercase letters in the alphabet. Instead of using an array, it generates the letters using a for loop.

The identi cation and diagnosis of failures is the starting point for meeting rehabilitation objectives and drafting a comprehensive code of practice for design. The author has carried out in-depth studies of such causes and their prevention from many independent sources. Only ve major sources are listed here: 1. According to Jean Louis Briaud of Texas A&M, a great number of bridges continue to fail due to ood, collision, and overload. Bridges with narrow waterway openings and erodible soils are most susceptible to bridge collapse. Other frequent principal causes are design, detailing, construction, and material defects.

Detecting a fault and locating it are two different things. Automatic monitoring is excellent for detecting faults and usually can provide sufficient localization to initiate

as RIP or OSPF. Some routing protocols, such as EIGRP, use autonomous systems, which group networks under a single administrative control. Administrative distance is used by a Cisco router to choose among multiple routing protocols to put a destination in the routing table. The routing protocol with the lowest administrative distance with a path to the destination is placed in the routing table. There are two types of routing protocols: static and dynamic. When choosing a dynamic routing protocol, you should consider routing metrics, how routing information is shared, convergence time, how routing information is processed, and routing overhead. Routing metrics define the method used to calculate a cost to a destination. For instance, RIP uses hop count. Distance vector protocols use broadcasts to share routing information and don t verify whether neighbors receive routing updates. They use the Bellman-Ford algorithm to process updates, which requires very little CPU processing and memory: They receive an update, increment the metrics, compare the results to the routing table, and update the routing table if necessary. Link state protocols use the SPF algorithm to build the routing table, providing a loop-free topology. They use multicasts to share routing information incrementally and verify that neighbors received this information. Link state protocols support classless routing and allow you to summarize networking information in your routing table. The main downside of these protocols is that they require more CPU cycles and memory to process and store routing information. They are also prone to flapping route problems. Hybrid protocols are based on the simplicity of a distance vector protocol but borrow from many features of link state protocols to make them more efficient and scalable. RIPv2, EIGRP, and BGP are examples of hybrid protocols. Distance vector protocols have problems with convergence and routing loops. Convergence is the amount of time it takes for all of the routers in the network to understand the current topology. Triggered updates can be used to speed up convergence. A routing loop is basically a disagreement about how to reach a particular network. Counting to infinity is resolved by placing a hop count limit to prevent packets from circling around the loop forever. Split horizon is used to prevent the creation of small routing loops: It prevents a router from advertising a route out the same interface from which the route was learned. Route poisoning, poison reverse, and hold-down timers are used to prevent large routing loops. A route is poisoned if a network connected to a router goes down. Poison reverse has a router advertise a poisoned route out all interfaces, including the interface from which it was learned. Hold-down timers keep the poisoned route in the routing table to ensure the poisoned route is propagated to all routers before any (worse) alternative paths are chosen.

Ethernet is the most widely used local area networking topology in the world. Its popularity is due to the fact that Ethernet delivers fast, reliable connectivity that is inexpensive and easy to install and maintain. Ethernet commonly is used to connect individual desktops to the site LAN. The original Ethernet specification was written in the early 1980s by a consortium composed of Digital Equipment Corporation, Intel Corporation, and Xerox. It specified a 10 Mbps data rate on a coaxial cable bus topology, and a contention resolution process called Carrier-Sense Multiple Access with Collision Detection, which is often abbreviated CSMA/CD. The CSMA/CD process allows any station to transmit on the network if no other station already is transmitting. In the event that two or more stations begin transmitting simultaneously (the likelihood of which depends on network load), there will be a collision. Both transmitting stations will detect that a collision has occurred, cease their transmission, and wait some specified amount of time before attempting to transmit again. A few years later the Ethernet specification was adopted by the IEEE (Institute of Electrical and Electronic Engineers) and rewritten as the IEEE 802.3 standard. The original Ethernet frame format was modified by the IEEE in the 802.3 specification, with the result that 802.3 is very similar but not the same as Ethernet. Ethernet and IEEE 802.3 are very similar local area network protocols providing connectivity at 10 Mbps media speed. Initially designed for use on coaxial cable, Ethernet/802.3 also is used on UTP (unshielded twisted-pair), STP (shielded twistedpair), and optical fiber. The frame formats for Ethernet and IEEE 802.3 are virtually identical (Figure 14.1), which allows both to coexist on the same network. Subtle differences prohibit interoperability, however. Though often wired in a physical star configuration, Ethernet/IEEE 802.3 is a logical bus, and all devices share the same transmission media (Figure 14.2). Only one device can transmit at a time. The media access method, as mentioned previously, is CSMA/CD: Each device must wait for the media to become quiet before transmitting, and must listen for other devices that might transmit at the same time. In the event of a collision, both devices will back off a certain period of time and try again. Modern Ethernet networks are wired in a physical star topology using the 10Base-T standard, as shown in Figure 14.3. The term 10Base-T refers to 10

To prevent this behavior, install the SQL instance using Mixed Mode Authentication. TIP: When building a database server (such as SQL for our deployment), set it up with two RAID configurations: one with RAID 1 (a two-drive mirror) for the operating system and the other with three or more drives using RAID 5 (striping with parity) for the database. This allows the OS and the SQL database to run on separate disk spindles, thus providing optimal performance, maximum uptime, and recovery capabilities. Citrix XenApp supports the following versions of Microsoft SQL Server for the farm s data store: SQL Server 2000 with Service Pack 3a: MDAC 2.8, Windows Server 2003 with Service Pack 1 SQL Server 2005: MDAC 2.8, Windows Server 2003 with Service Pack 1 SQL Server 2005: MDAC 2.8, Windows Server 2003 x64