IPTV training course description A current hot topic in recent years has been the provision of multimedia services over IP networks aka triple or quadruple play. This course investigates the characteristics of video transmission and then studies the impact on IP networks. What will you learn Use Wireshark to analyse and troubleshoot TV streams. Describe techniques, which can be used in IP to provide low uniform delay. Evaluate IPTV technologies. Design data networks, which will support IPTV. IPTV training course details Who will benefit: Anyone working with IPTV. Prerequisites: TCP/IP Foundation for engineers Intro to data communications & networking. Duration 3 days IPTV training course contents What is IPTV? What is IP? What is TV? Pixels, frames, colour, digital modulation, digital video broadcasting. SDTV, HDTV, 4K. IPTV architectures, Contribution, distribution, delivery. IPTV standards. Hands on Base IP connectivity, VLC. IPTV protocol stacks IP, TCP, UDP, RTP. IPv6. HTTP. Bandwidth requirements. Hands on IPTV bandwidth calculations. Video codecs What is a CODEC, pictures and audio, digitisation, sampling, quantisation, encoding, compressing. MPEG, bit rates, resolution. I, B, P frames, GOP. MPEG 2, MPEG 4, H.264, H.265, VP9, AV1. Hands on Analysing MPEG frames. IP issues Quality vs. bandwidth. Bandwidth, delay, latency, jitter, signalling. Routers. Hands on Analysing jitter and other performance issues. IPTV performance and QoS IP DSCP field, queuing strategies; FIFO, WFQ, custom, priority, RED. Differentiated services, Diffserv. 802.1Q. Traffic shaping. QoE. Hands on best effort versus prioritisation. UDP versus TCP Reliable, unreliable, connection oriented, connectionless. Broadcasts, multicasts and unicasts. TCP flow control, TCP and performance. Hands on TCP window sizes. RTP RTP, ports, mixers, translators, RTCP, SMPTE, FEC. Hands on RTP analysis with Wireshark. Multicasting Multicasting compared to unicasting and broadcasting, when to use and when not to use multicasting. IGMP, PIM-SM, SSM. MLD. Hands on Analysing multicast streams. OTT TV HTTP, HTTPS, Chunked HTTP. Adaptive streaming. HTML5. DASH vs HLS. Hands on Analysing HTTP streams. Security Firewalls, TLS, DRM, watermarking. Encryption. Geolocation. VPNs. IPTV architecture and other protocols Content providers, Service providers, delivery networks, home networks. Caching, Service discovery. RTSP. SAP, SDP. DHCP, DNS, NTP Hands on Fixing the network.
Definitive Ethernet switching course description A hands on comprehensive look at Ethernet switches with extensive coverage of VLANs. The course focuses on the technology and not any one manufacturers product enabling delegates to configure switches from any manufacturer. What will you learn Configure and troubleshoot switches using: Console port telnet HTTP TFTP Configure and troubleshoot switch features such as: Duplex/speed Port based MAC security Spanning Tree Link aggregation Tagged ports Configure and troubleshoot VLANs. Definitive Ethernet switching course details Who will benefit: Technical staff. Prerequisites: Intro to data communications & networking. Duration 3 days Definitive Ethernet switching course contents What is Ethernet? LANs, network cards and cables, CSMA/CD, Ethernet frames, Ethernet evolution, 802.3. Hands on: ping, Ethernet speeds, CSMA/CD. Ethernet layer 2 Layer 2 functions, NICs, MAC addresses, unicasts, multicasts and broadcasts, frame formats. Hands on: Configuring NICs, Analysing MAC addresses with Wireshark IP and Ethernet Relationship Hands on: ARP. What is a switch? Switches connect multiple devices, switches versus hubs, simultaneous conversations, switches work at layer 2, the forwarding database, how the forwarding database is built, broadcast and collision domains Hands on: Difference between hubs and switches. Switch configuration Switch configuration Managed/unmanaged switches, configuration methods, reasons to configure switches. Console ports, HyperTerminal (and alternatives). Hands on: Using the console port to troubleshoot and configure switches. Switches in more detail Latency, forwarding mechanisms, switch fabrics. Hands on: Using telnet and HTTP to switches. Ethernet extensions Auto negotiation, Power over Ethernet. Hands on:Configuring and troubleshooting switch ports: Speed, duplex and security. Redundant links Loops, broadcast storms, STP, BPDU format, STP convergence. Hands on: Tracking blocked ports. STP convergence. Backbone links Architectures, link aggregation, LACP, load sharing, resilience. Hands on: fail over times. VLANs Virtual versus physical LANs, Why have VLANs? Broadcast domains, Creating VLANs, Assigning ports to VLANs. Hands on: Analysing the effect of VLANs on traffic. Enterprise VLANs VLANS are internal, multiple VLANs, Load balancing, Default VLAN, VLAN registration protocols: VTP, GVRP, MVRP. Hands on: VLANs on multiple switches. Tagging/Trunking Reason for tagging, terminology, tagging process, 802.1Q, Tag format, VLAN stacking. Hands on: Configuring and troubleshooting tags. STP variants RSTP, Common STP, Multiple STP, PVST, ring alternatives. Hands on: RSTP. Inter VLANs Layer 3 switching, IP addressing rules, Interconnecting VLANs. Hands on: Routing between VLANs. Troubleshooting Ethernet Methods, tools, locating faults, layer 1 issues, layer 2 issues Hands on: Fixing the network.
LINX 1 training course description An intensive hands on IP foundation leading to LINX Accredited Internet Technician stage 1. The course focuses on all parts of TCP/IP including layers 4 to 7 on end stations as well as layer 3 on routers. The TCP/IP protocols are also studied to enable delegates to be able to troubleshoot TCP/IP using Wireshark. Hands on sessions are used to reinforce the theory rather than teach specific manufacturer equipment. A multiple choice exam, leading to the LAIT I certification, is available after the course. The exam consists of 40 questions and lasts 1.5 hours. What will you learn Use ping, traceroute and other tools to diagnose faults on a network. Configure IP on PCs and routers. Plan IP addresses and subnets. Analyse IP and TCP packets using an analyser. Troubleshoot TCP/IP. LINX 1 training course details Who will benefit: Network engineers. Prerequisites: None. Duration 5 days LINX 1 training course contents What is TCP/IP? TCP and IP are protocols, 7 layer model, network layers, hardware/software layers, internetworking, protocols, What is IP? What is TCP? The internet, The IAB, RFCs. Ping and Wireshark Host configuration, IP addresses, subnet masks, default gateways, ping. Hands on Base configuration. Testing with ping. Analysing packets with Wireshark. Switches and Wireshark Switches versus hubs, layer 2 forwarding table, flooding, broadcasts. Hands on Building a switched based network. Configuring network devices Configuration options, console port, putty, telnet. Hands on Configuring switches, telnet. IP IP packet format, protocol field, TTL, DiffServ, fragments, ICMP. Hands on IP packet analysis. IP addressing 32 bits, dotted decimal, rules, networks, role of subnet masks, simple subnetting, prefix notation. Broadcasts, special use addresses. Hands on Planning and implementing addressing. IP and the lower layers ARP, media not supporting ARP. Hands on ARP. Routing What are routers? What routers do, default gateways, routing and addressing, routing tables, ways to update routing tables. Hands on Building a routed network, traceroute. Routing protocols IGPs and EGPs, RIP, RIPv2, Why not to use RIP, OSPF, OSPF metrics, convergence, distance vector protocols, link state protocols. Hands on OSPF, analysing routing tables, loopbacks. Network simulators Network simulators, EVE-NG, GNS3, CML. Hands on Using EVE-NG. Subnetting Subnetting to the bit level, ranges, how prefixes are used. Hands on Subnetting. VLANS and IP addressing What are VLANs, tagging, 802.1Q, Inter VLAN routing. Hands on Inter VLAN routing. TCP and UDP Layer 4, port numbers, client ports, broadcasts multicasts and layer 4, UDP header, TCP header, connections, ACK, sliding windows, options, connection states. Sockets. Hands on Analysing TCP packets. IPv4 address configuration Private addresses, NAT, NAPT, dynamic addressing, DHCP, link local addresses. Hands on DHCP, NAT. IPv6 What is IPv6, 128 bit addresses, address formats, IPv6 address allocation, header format, migration, dual stack, tunnelling, NAT64, DNS64. Hands on IPv6 setup troubleshooting. IPv6 address configuration Static addressing, EUI-64 addresses, IPv6 address order, SLAAC, DHCPv6. Hands on SLAAC. Applications Clients, servers, HTTP, Email, resource sharing, VoIP, video, terminal emulation, remote desktop. Network management and SNMP. Hands on Servers, TFTP, VoIP packet analysis. DNS Names and addresses, hosts file, how DNS works. FQDNs, DNS client configuration. Hands on Troubleshooting DNS. Security Firewalls, firewall architectures, DMZ, how firewalls work, proxy servers, filtering, ACLs, IDS, VPNs, authentication, encryption, tunnels, secure protocols. Hands on Firewalls, SSH Troubleshooting Methods, tools. Using the 7 layer model. Troubleshooting toolkits. Hands on Fixing the network.
Network fundamentals training course description An intensive hands on IP foundation leading to LINX Accredited Internet Technician stage 1. The course focuses on all parts of TCP/IP including layers 4 to 7 on end stations as well as layer 3 on routers. The TCP/IP protocols are also studied to enable delegates to be able to troubleshoot TCP/IP using Wireshark. Hands on sessions are used to reinforce the theory rather than teach specific manufacturer equipment. A multiple choice exam, leading to the LAIT I certification, is available after the course. The exam consists of 40 questions and lasts 1.5 hours. What will you learn Use ping, traceroute and other tools to diagnose faults on a network. Configure IP on PCs and routers. Plan IP addresses and subnets. Analyse IP and TCP packets using an analyser. Troubleshoot TCP/IP. Network fundamentals training course details Who will benefit: Network engineers. Prerequisites: None Duration 5 days Network fundamentals training course contents What is TCP/IP? TCP and IP are protocols, 7 layer model, network layers, hardware/software layers, internetworking, protocols, What is IP? What is TCP? The internet, The IAB, RFCs. Ping and Wireshark Host configuration, IP addresses, subnet masks, default gateways, ping. Hands on Base configuration. Testing with ping. Analysing packets with Wireshark. Switches and Wireshark Switches versus hubs, layer 2 forwarding table, flooding, broadcasts. Hands on Building a switched based network. Configuring network devices Configuration options, console port, putty, telnet. Hands on Configuring switches, telnet. IP IP packet format, protocol field, TTL, DiffServ, fragments, ICMP. Hands on IP packet analysis. IP addressing 32 bits, dotted decimal, rules, networks, role of subnet masks, simple subnetting, prefix notation. Broadcasts, special use addresses. Hands on Planning and implementing addressing. IP and the lower layers ARP, media not supporting ARP. Hands on ARP. Routing What are routers? What routers do, default gateways, routing and addressing, routing tables, ways to update routing tables. Hands on Building a routed network, traceroute. Routing protocols IGPs and EGPs, RIP, RIPv2, Why not to use RIP, OSPF, OSPF metrics, convergence, distance vector protocols, link state protocols. Hands on OSPF, analysing routing tables, loopbacks. Network simulators Network simulators, EVE-NG, GNS3, CML. Hands on Using EVE-NG. Subnetting Subnetting to the bit level, ranges, how prefixes are used. Hands on Subnetting. VLANS and IP addressing What are VLANs, tagging, 802.1Q, Inter VLAN routing. Hands on Inter VLAN routing. TCP and UDP Layer 4, port numbers, client ports, broadcasts multicasts and layer 4, UDP header, TCP header, connections, ACK, sliding windows, options, connection states. Sockets. Hands on Analysing TCP packets. IPv4 address configuration Private addresses, NAT, NAPT, dynamic addressing, DHCP, link local addresses. Hands on DHCP, NAT. IPv6 What is IPv6, 128 bit addresses, address formats, IPv6 address allocation, header format, migration, dual stack, tunnelling, NAT64, DNS64. Hands on IPv6 setup troubleshooting. IPv6 address configuration Static addressing, EUI-64 addresses, IPv6 address order, SLAAC, DHCPv6. Hands on SLAAC. Applications Clients, servers, HTTP, Email, resource sharing, VoIP, video, terminal emulation, remote desktop. Network management and SNMP. Hands on Servers, TFTP, VoIP packet analysis. DNS Names and addresses, hosts file, how DNS works. FQDNs, DNS client configuration. Hands on Troubleshooting DNS. Security Firewalls, firewall architectures, DMZ, how firewalls work, proxy servers, filtering, ACLs, IDS, VPNs, authentication, encryption, tunnels, secure protocols. Hands on Firewalls, SSH Troubleshooting Methods, tools. Using the 7 layer model. Troubleshooting toolkits. Hands on Fixing the network.
TCP/IP training course description An intensive hands on IP foundation leading to LINX Accredited Internet Technician stage 1. The course focuses on all parts of TCP/IP including layers 4 to 7 on end stations as well as layer 3 on routers. The TCP/IP protocols are also studied to enable delegates to be able to troubleshoot TCP/IP using Wireshark. Hands on sessions are used to reinforce the theory rather than teach specific manufacturer equipment. A multiple choice exam, leading to the LAIT I certification, is available after the course. The exam consists of 40 questions and lasts 1.5 hours. What will you learn Use ping, traceroute and other tools to diagnose faults on a network. Configure IP on PCs and routers. Plan IP addresses and subnets. Analyse IP and TCP packets using an analyser. Troubleshoot TCP/IP. TCP/IP training course details Who will benefit: Network engineers. Prerequisites: None Duration 5 days TCP/IP training course contents What is TCP/IP? TCP and IP are protocols, 7 layer model, network layers, hardware/software layers, internetworking, protocols, What is IP? What is TCP? The internet, The IAB, RFCs. Ping and Wireshark Host configuration, IP addresses, subnet masks, default gateways, ping. Hands on Base configuration. Testing with ping. Analysing packets with Wireshark. Switches and Wireshark Switches versus hubs, layer 2 forwarding table, flooding, broadcasts. Hands on Building a switched based network. Configuring network devices Configuration options, console port, putty, telnet. Hands on Configuring switches, telnet. IP IP packet format, protocol field, TTL, DiffServ, fragments, ICMP. Hands on IP packet analysis. IP addressing 32 bits, dotted decimal, rules, networks, role of subnet masks, simple subnetting, prefix notation. Broadcasts, special use addresses. Hands on Planning and implementing addressing. IP and the lower layers ARP, media not supporting ARP. Hands on ARP. Routing What are routers? What routers do, default gateways, routing and addressing, routing tables, ways to update routing tables. Hands on Building a routed network, traceroute. Routing protocols IGPs and EGPs, RIP, RIPv2, Why not to use RIP, OSPF, OSPF metrics, convergence, distance vector protocols, link state protocols. Hands on OSPF, analysing routing tables, loopbacks. Network simulators Network simulators, EVE-NG, GNS3, CML. Hands on Using EVE-NG. Subnetting Subnetting to the bit level, ranges, how prefixes are used. Hands on Subnetting. VLANS and IP addressing What are VLANs, tagging, 802.1Q, Inter VLAN routing. Hands on Inter VLAN routing. TCP and UDP Layer 4, port numbers, client ports, broadcasts multicasts and layer 4, UDP header, TCP header, connections, ACK, sliding windows, options, connection states. Sockets. Hands on Analysing TCP packets. IPv4 address configuration Private addresses, NAT, NAPT, dynamic addressing, DHCP, link local addresses. Hands on DHCP, NAT. IPv6 What is IPv6, 128 bit addresses, address formats, IPv6 address allocation, header format, migration, dual stack, tunnelling, NAT64, DNS64. Hands on IPv6 setup troubleshooting. IPv6 address configuration Static addressing, EUI-64 addresses, IPv6 address order, SLAAC, DHCPv6. Hands on SLAAC. Applications Clients, servers, HTTP, Email, resource sharing, VoIP, video, terminal emulation, remote desktop. Network management and SNMP. Hands on Servers, TFTP, VoIP packet analysis. DNS Names and addresses, hosts file, how DNS works. FQDNs, DNS client configuration. Hands on Troubleshooting DNS. Security Firewalls, firewall architectures, DMZ, how firewalls work, proxy servers, filtering, ACLs, IDS, VPNs, authentication, encryption, tunnels, secure protocols. Hands on Firewalls, SSH Troubleshooting Methods, tools. Using the 7 layer model. Troubleshooting toolkits. Hands on Fixing the network.
SAFe® Product Owner / Product Manager: In-House Training Develop the skillsets needed to guide the delivery of value in a Lean Enterprise by becoming a SAFe® 5.0 Product Owner / Product Manager (POPM). During this course, attendees gain an in-depth understanding of how to effectively perform their role in the Agile Release Train (ART) as it delivers value through Program Increments. Attendees explore how to apply Lean thinking to decompose Epics into Features and Stories, refine Features and Stories, manage Program and Team backlogs, and plan and execute Iterations and Program Increments. Attendees also discover how the Continuous Delivery Pipeline and DevOps culture contribute to the relentless improvement of the ART. What you will Learn To perform the role of a SAFe® Product Owner / Product Manager, attendees should be able to: Articulate the Product Owner and Product Manager roles Connect SAFe® Lean-Agile principles and values to the PO / PM roles Decompose Epics into Features and decompose Features into Stories Manage Program and Team backlogs Collaborate with Agile teams in estimating and forecasting work Represent customer needs in Program Increment Planning Execute the Program Increment and deliver continuous value Becoming a Product Owner / Product Manager in the SAFe® enterprise Preparing for PI Planning Leading PI Planning Executing Iterations Executing the Program Increment Becoming a Certified SAFe® Product Owner / Product Manager
ADO.NET training course description This ADO.net training course is designed to enable developers to use the toolset provided with.NET for data access including ADO.net objects, data controls, designers and interoperability with earlier ADO objects. The course is applicable for those using C# or VB.NET with ADO.NET What will you learn Retrieve and manipulate data using Microsoft's ADO.NET library. Work with the ADO.NET object model. Update data, including handling stored procedures, parameters, and return value. Search, sort and filter data. Leverage the power of XML. ADO.NET training course details Who will benefit: Programmers working with ADO.Net. Prerequisites: Effective programming with VB.NET or Concise introduction to C# Duration 2 days ADO.NET training course contents Introducing ADO.Net Traditional Data Access Architecture. ADO.Net Disconnected Data Access Architecture. Different components of ADO.Net. A review of basic SQL queries SQL SELECT Statement. SQL INSERT Statement. SQL UPDATE Statement. SQL DELETE Statement. Common data access tasks with ADO.Net Accessing Data using ADO.Net. Defining the connection string. Defining a Connection. Defining the command or command string. Defining the Data Adapter. Creating and filling the DataSet. A Demonstration Application The Interface. Loading the table. Filling the controls on the Form. Navigating through the records. Updating Data Steps for updating the table. Building the Application. Loading the table and displaying data in the form's controls. Initialising Commands. Adding Parameters to the commands. The ToggleControls() method of our application. Editing (or Updating) Records. Event Handler for the Save Button. Event Handler for the Cancel Button. Inserting Records. Deleting a Record. Using Stored Procedures Sample Stored Procedures. UPDATE Stored Procedure. INSERT Stored Procedure. DELETE Stored Procedure. SELECT Stored Procedure. Using Stored Procedures with ADO.Net.
Software development training course description This three-day MTA Training course helps you prepare for Microsoft Technology Associate Exam 98-361, and build an understanding of these topics: Core programming, Object-Oriented programming, general software development, web applications, desktop applications, and databases. This course leverages the same content as found in the Microsoft Official Academic Course (MOAC) for this exam. What will you learn Describe core programming. Explain Object Oriented programming. Describe general software development. Describe Web applications. Describe desktop applications. Explain how databases work. Software development training course details Who will benefit: Anyone looking to learn the fundamentals of software. Prerequisites: None. Duration 3 days Software development training course contents Core programming Computer storage and data types How a computer stores programs and the instructions in computer memory, memory stacks and heaps, memory size requirements for the various data storage types, numeric data and textual data. Computer decision structures Various decision structures used in all computer programming languages; If decision structures; multiple decision structures, such as Ifâ¦Else and switch/Select Case; reading flowcharts; decision tables; evaluating expressions. Handling repetition For loops, While loops, Do...While loops and recursion. Understand error handling Structured exception handling. Object-oriented programming Classes Properties, methods, events and constructors; how to create a class; how to use classes in code. Inheritance Inheriting the functionality of a base class into a derived class. Polymorphism Extending the functionality in a class after inheriting from a base class, overriding methods in the derived class. Encapsulation Creating classes that hide their implementation details while still allowing access to the required functionality through the interface, access modifiers. General software development Application life cycle management Phases of application life cycle management, software testing. Interpret application specifications Application specifications, translating them into prototypes, code, select appropriate application type and components. Algorithms and data structures Arrays, stacks, queues, linked lists and sorting algorithms; performance implications of various data structures; choosing the right data structure. Web applications Web page development HTML, CSS, JavaScript. ASP.NET web application development Page life cycle, event model, state management, client-side versus server-side programming. Web hosting Creating virtual directories and websites, deploying web applications, understanding the role of Internet Information Services. Web services Web services that will be consumed by client applications, accessing web services from a client application, SOAP, WSDL. Desktop applications Windows apps UI design guideline categories, characteristics and capabilities of Store Apps, identify gestures. Console-based applications Characteristics and capabilities of console- based applications. Windows Services Characteristics and capabilities of Windows Services. Databases Relational database management systems Characteristics and capabilities of database products, database design, ERDs, normalisation concepts. Database query methods SQL, creating and accessing stored procedures, updating and selecting data. Database connection methods Connecting to various types of data stores, such as flat file; XML file; in-memory object; resource optimisation.
ASP.Net training course description Our hands on ASP.NET training course that will teach students how to create a simple ASP.NET application that delivers dynamic content to the web. The course is applicable for those using C# or VB.NET with ASP.NET. What will you learn Create a web form with server controls Separate page code from content with code-behind pages, page controls, and components. Display dynamic data from a data source by using ADO.NET and data binding. Debug ASP.NET pages by using trace. ASP.Net training course details Who will benefit: Programmers working with ASP.NET. Prerequisites: HTML5 development fundamentals VBNet_course.htm or C++ programming foundation Duration 3 days ASP.Net training course contents Working with ASP.NET Introducing ASP.NET. Creating web forms. Adding ASP.NET code to a page. Handling page events. Using Web Controls Web controls and HTML controls compared. Using intrinsic controls. Using input validation controls. Introduction to user controls. Using trace in ASP.NET pages Overview of tracing. Trace information. Page-level trace and application-level trace. Separating code from content Advantages of partitioning an ASP.NET page. Creating and using code-behind pages. Creating and using components and classes. Inheritance of classes. Interfaces. Using ADO .NET to access data Accessing text files. Overview of ADO .NET Connecting to a data source. Accessing data with DateSets. Using DataViews. Accessing data with DataReaders. Using XML data with a DataSet. Creating an ASP.NET Web Application Requirements of a web application. Sharing information between pages. Securing an ASP.NET application. Web services. Creating a simple web service using Visual Studio.NET Calling a web service using Visual Studio.NET
Complete Ruby programming training course description This course starts with a quick-start session and then explains the language in detail from the bottom up. Hands on sessions follow all the major sessions to reinforce the theory. What will you learn Read Ruby programs. Write Ruby programs. Debug Ruby programs. Complete Ruby programming training course details Who will benefit: Anyone wishing to program in Ruby. Prerequisites: Software development fundamentals Duration 3 days Complete Ruby programming training course contents Introduction A tour of Ruby, Try Ruby, A suduko solver in Ruby. The Structure and execution of Ruby Lexical structure, Syntactic structure, Files structure, Program encoding, Program execution. Datatypes and objects Numbers, text, Arrays, Hashes, Ranges, Symbols, True, false, and nil, Objects. Expressions and operators Literals and keyword literals, Variable references, Constant references, Method invocations, Assignments, Operators. Statements and control structures Conditionals, loops, Iterators and enumerable objects, Blocks, Altering flow control, Exceptions and exception handling, BEGIN and END, Threads, fibres and continuations. Methods, Procs, Lambdas and closures Defining simple methods, Method names, Methods and parentheses, Method arguments, Procs and lambdas, Closures, Method objects, Functional programming. Classes and modules Defining a simple class, Method visibility: public, protected, privates, Subclassing and inheritance, Object creation and initialization, Modules, Loading and requiring modules, Singleton methods and Eigenclass, Method lookup, Constant lookup. Reflection and metaprogramming Types, classes and modules, Evaluating strings and blocks, Variables and constants, Methods, Hooks, Tracing, ObjectSpace and GV, Custom control structures, Missing methods and missing constants, Dynamically creating methods, Alias chaining. The Ruby platform Strings, Regular expressions, Numbers and Math, Dates and times, Collections, Files and directories, Input/output, Networking, Threads and concurrency. The Ruby environment Invoking the Ruby interpreter, The Top-level environment, Practical extraction and reporting shortcuts, Calling the OS, Security.