Expert System Shells and Products in .NET

Creator PDF-417 2d barcode in .NET Expert System Shells and Products

SIP is a protocol for controlling multimedia sessions in an IP Network. In this chapter we only cover basic SIP functionality. We begin this section with the introduction of an important SIP component, the SIP-speci c identi er, and then give an overview of how session control is performed on the basis of SIP identi er and a dedicated SIP infrastructure. We continue with an overview of the SIP protocol structure. The SIP protocol itself only transports session descriptions. It does not understand them. We therefore also look at the language for describing multimedia sessions, the Session Description Protocol (SDP). We close this section by describing a number of example SIP ows.

To peek inside .dll files, you just need to know the exact structure they use to organize their content. The following script reveals all the hidden information stored in a PE-compliant .dll file. It uses a COM object I developed to decipher the PE-DLL-file format (see Figure 4-9). You ll find full source code on the companion CD. Just make sure you install the COM object on the companion CD before you launch the script: \install\ dll\setup.exe.

If we want to intercept imported functions, we have several options. We can change addresses in the IAT of our target module so that they point to our hook functions. This method will allow us to monitor the use of a function of interest only within a certain module. If we want to monitor every use of a function, regardless of the module that is accessing it, we can modify the function code itself to redirect somewhere else temporarily during execution.

sub CheckFolder(folderobj) determine folder size important: always turn off error handling! on error resume next size = folderobj.size check for access violation errors if not err.Number=0 then size=-1 err.clear end if turn error handling back on: on error goto 0 add entry: folderspecs(counter,0) = size folderspecs(counter,1) = folderobj.path increment counter: counter = counter + 1 check all subfolders this is the basis of recursive calling important! Always turn off error handling to handle access violation errors: on error resume next for each subfolder in folderobj.subfolders check each subfolder individually by calling myself CheckFolder subfolder next turn error handling back on: err.clear on error goto 0 end sub Sub SortInfo for x = 0 to counter-1 for y = x+1 to counter-2 if folderspecs(x,0)<folderspecs(y,0) then wrong order Switch! temp = folderspecs(x,0) folderspecs(x,0)=folderspecs(y,0) folderspecs(y,0)=temp temp = folderspecs(x,1) folderspecs(x,1)=folderspecs(y,1) folderspecs(y,1)=temp

This will be displayed in a style something like the following:

For benchmarking, Computerworld offers a very straightforward definition: "Benchmarking is a measurement tool used to gauge a company's operating performance against that of competitors to identify best practices and make improvements. Examples within corporate IT include measuring the costs of supporting a data center or network infrastructure." But then they address e-commerce benchmarking as a separate entity: "E-commerce benchmarking is used to help companies compare the costs and performance of their online operations with those of other companies." In the Computerworld article defining e-commerce benchmarking, Mark Czarnecki, president of The Benchmarking Network, Inc., says, "All the concepts and principles of e-commerce are still not set," making benchmarks very difficult: Normally, there's a set of "anchors" that companies can rely on when they do benchmarking a defined measure of performance, such as transactions per second or monthly sales, Czarnecki says. "Defining it means there's some kind of stable business process. [With e-commerce], there's not a stable business process," he adds. The top priority for electronic businesses is turning a profit, says Jim Sample, a consultant at Reston, Va.-based benchmarking service provider Compass America Inc. "The drive toward profitability then trickles back to having to put in some traditional measurement system," he says.

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Section 6.4 contained an example illustrating how the hiding of previously submitted data in subsequently generated dynamic form pages can preserve client state. That scheme works in part, but it is only really useful if you are working through a fixed sequence of forms, all of which must be completed in a specific order. There are many other situations where it is useful to maintain some representation of client state, even though the client is going to be moving around, following different links to various parts of your web site. Consider for instance a web site where you want to include advertisements in the banner portion of the pages that you return, most of these pages being essentially static information. Your client will be following arbitrary links amongst your pages, but you would still like to save client state if simply something like a record of the advertisements that the client has already seen, so that you can show other products. But you don t have any forms, and there are no form submission actions that you could rely on to return hidden field data. Persistent state client side cookies are the basis of an alternative mechanism for preserving state. Cookies are:

The probability that the channel is idle for a time slot is 1 pb . The probability that the channel is neither idle nor successful for a time slot is [1 (1 pb ) ps ] = pb ps . Let TE(L), Ts , and Tc denote the time to transmit the average payload, the average time required to transmit a PCA packet successfully, and the average time that the PCA channel has a collision, respectively. The fraction of PCA periods in a superframe, denoted by FPCA , is given by FPCA = NPCA . NSF (12.36)

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