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  • Definition of domains in mySQL?

    - by mal
    I'm working on a college exercise and have the following question: What is the domain of the "country" table? My understanding of domain is that it defines the possible values of an attribute. This means that the table "country" doesn't have a domain, but the various attributes in the table "country" have their own domains. For example the attribute "SurfaceArea" has the domain FLOAT(10,2) and the attribute "Name" has the domain CHAR(52). Is this correct?

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  • Return more then One field from database SQLAlchemy

    - by David Neudorfer
    This line: used_emails = [row.email for row in db.execute(select([halo4.c.email], halo4.c.email!=''))] Returns: ['[email protected]', '[email protected]', '[email protected]', '[email protected]', '[email protected]'] I use this to find a match: if recipient in used_emails: If it finds a match I need to pull another field (halo4.c.code) from the database in the same row. Any suggestions on how to do this?

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  • Current state of Erlang web development? Frameworks, Template languages

    - by pommonico
    Django is to Python as Rails is to Ruby. What is the current front-runner for Erlang? Recent Erlang web activity has resulted in many new frameworks but they are all still moving targets. ErlyWeb is very far along but now seems to be dead. If you were to invest significant capital into a new web product (i.e. not a hobby, you use your own money and you use other's investment in you with expectation of payback), would you choose Erlang as a web platform? If so, what framework and technologies would you choose?

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  • .NET - Where can I start? [closed]

    - by mustang2009cobra
    I'm a moderately experienced developer with experience developing using a variety of languages. I've done C++, Java, PHP, Javascript, and several other languages. I remember the Java dev stack being rather difficult to dive into, but it's nothing like the endless sea of the .NET framework. I'd like to become experienced in .NET development, as many dev shops are microsoft-centric. But I'm a little unsure as to where the best place to start is. As I already know a bunch of programming languages, I don't really need resources that will help me learn C# or any of the .NET languages as much as I need to learn the development stack, APIs, etc. Any suggestions on the best way to start learning .NET development?

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  • Are There Any Other Web Programming Languages That Can Be Used Without A Framework Aside From PHP?

    - by Ygam
    Python needs a framework, so does Java (for the web). I don't know much about Ruby or Coldfusion. But is there another language out there for the web that can stand alone as it is without a need for a framework or without strict adherence to a design pattern (MVC and the likes) aside from PHP? BTW, the statement that Python and Java needs a framework to work with the web came purely from my readings on articles and books; I might be mistaken.

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  • Are programming languages and methods ineffective? (assembler and C knowledge needed)

    - by b-gen-jack-o-neill
    Hi, for a long time, I am thinking and studying output of C language compiler in asemlber form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually trully believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example: 1, Stack local scope memory allocation: So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when adress you desire is further translated before reaching actuall RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Becouse you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect adressing, "my" way would be even faster. 2, Variable allocation duplicitly: When you run aaplication, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actuall instruction for do so, and that actuall number in memory. So, there are 2 entries of the same value in RAM. One in fomr of instruction, second in form of actuall bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

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  • Are there alternative ways to implementing an "active link" navigation without using server side languages?

    - by Mel
    By "active" I mean to have the link pointing to the current page classed as "active." This way the link's appearance can be modified using css. Is it possible to implement an active link navigation without using a server side language? I would like to only use CSS/HTML/jQuery if possible. If there are, what are those methods? Assuming you want to create the following structure: <ul id="nav"> <li class="active">Home</li> <li>About</li> <li>Contact</li> </ul>

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  • Are Domain Specific Languages (DSL) bad for the Common Programmer?

    - by iestyn
    I have lately been delving into F# and the new DSL stuff as in the Microsoft SQL Server Modelling CTP, and have some concerns. Will this new idea that will come about be bad for skilled programmers? Is code going to be dumbed down? I know I sound like a luddite, but this does worry me, after spending years of time practising in my craft, and now might be scuttled by genius from within. I am afraid, very afraid. Will I be now trapped in a job that only programs against a DSL and therefore every job that I work on, I have to learn a whole new DSL based on top of a Framework (.net Java), that I will only be allowed to touch certain parts of. I don't think the world is ready for DSL, but the sales pitch is deafening!

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  • Is existed web markup languages with possibility insert sql query?

    - by MercurieVV
    Actually what I want - simple DB with simple User Interface. Like MS Access, but for web and it can be without Dragn n Drop, but described with markup language. For example if I want to create list report, then i need to write something like: <table query="SELECT * from mytable"></table> It needed for simple data applications. In that kind application no programming logic required. Just working with DB. Changing DB data and showing it.

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  • IMAPSync Migration to Exchange 2010 SP1: Exchange drops connections while checking for existence of folders

    - by Benjamin Priestman
    I'm migrating from ZImbra Collaboration Suite to Exchange 2010 SP1. I'm testing IMAPSync as a possible migration tool and have hit a problem with the IMAP server in Exchange 2010. For each account it migrates, IMAPSync loops through the list of folders in the source mailbox and tests for the existence of each one in the destination mailbox. It then goes on to create those folders that do not exist and copy over the messages. It's the intial testing for the existence of the folders that is giving me a problem. The response given by the Exchange server when the folder does not yet exist is given as an error: "R=""16 NO IMAPSyncTest/8 doesn't exist."" After ten of these errors have been issued in succession, the Exchange server appears to stop responding to the IMAP session. Enabling protocol logging for IMAP confirms that the 10th request for a non-existant folder is the last request to be logged on the server. IMAPSync carries on merrily without seeming to realise its connection has gone and thus fails to create any folders. I've logged this with the tool's creator. Does anyone have any idea why Exchange is stopping responding to the connections though? The behaviour looks rather like throttling, although the 'ten strikes and you're out' trigger does not seem to correspond to any of the triggers on the ThrottlingPolicies. Just to check, I've tried creating a new ThrottlingPolicy, turned everything that I think might be relevant up to 11 and applied it to the my test mailbox. Policy settings are listed below, along with IMAP settings. Everything else should be pretty much as default. Throttling Policy RunspaceId : afa3159c-32a6-4906-986f-8adfbe50868b IsDefault : False AnonymousMaxConcurrency : 1 AnonymousPercentTimeInAD : AnonymousPercentTimeInCAS : AnonymousPercentTimeInMailboxRPC : EASMaxConcurrency : 10 EASPercentTimeInAD : EASPercentTimeInCAS : EASPercentTimeInMailboxRPC : EASMaxDevices : 10 EASMaxDeviceDeletesPerMonth : EWSMaxConcurrency : 10 EWSPercentTimeInAD : 50 EWSPercentTimeInCAS : 90 EWSPercentTimeInMailboxRPC : 60 EWSMaxSubscriptions : 5000 EWSFastSearchTimeoutInSeconds : 60 EWSFindCountLimit : 1000 IMAPMaxConcurrency : 1000 IMAPPercentTimeInAD : 400 IMAPPercentTimeInCAS : 400 IMAPPercentTimeInMailboxRPC : 400 OWAMaxConcurrency : 5 OWAPercentTimeInAD : 30 OWAPercentTimeInCAS : 150 OWAPercentTimeInMailboxRPC : 150 POPMaxConcurrency : 20 POPPercentTimeInAD : POPPercentTimeInCAS : POPPercentTimeInMailboxRPC : PowerShellMaxConcurrency : 18 PowerShellMaxTenantConcurrency : PowerShellMaxCmdlets : PowerShellMaxCmdletsTimePeriod : ExchangeMaxCmdlets : PowerShellMaxCmdletQueueDepth : PowerShellMaxDestructiveCmdlets : PowerShellMaxDestructiveCmdletsTimePeriod : RCAMaxConcurrency : 1000 RCAPercentTimeInAD : 400 RCAPercentTimeInCAS : 400 RCAPercentTimeInMailboxRPC : 400 CPAMaxConcurrency : 20 CPAPercentTimeInCAS : 205 CPAPercentTimeInMailboxRPC : 200 MessageRateLimit : RecipientRateLimit : ForwardeeLimit : CPUStartPercent : 75 AdminDisplayName : ExchangeVersion : 0.10 (14.0.100.0) Name : TestMigrationThrottling DistinguishedName : CN=TestMigrationThrottling,CN=Global Settings,CN=Our Company,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=cimex,DC=com Identity : TestMigrationThrottling Guid : 240049b3-2023-4df1-8edc-fbfc1fc80b87 ObjectCategory : domain.com/Configuration/Schema/ms-Exch-Throttling-Policy ObjectClass : {top, msExchGenericPolicy, msExchThrottlingPolicy} WhenChanged : 21/04/2011 18:48:19 WhenCreated : 21/04/2011 18:07:20 WhenChangedUTC : 21/04/2011 17:48:19 WhenCreatedUTC : 21/04/2011 17:07:20 OrganizationId : OriginatingServer : a-domain-controller IsValid : True IMAPSettings RunspaceId : afa3159c-32a6-4906-986f-8adfbe50868b ProtocolName : IMAP4 Name : 1 MaxCommandSize : 10240 ShowHiddenFoldersEnabled : False UnencryptedOrTLSBindings : {192.168.x.x:143} SSLBindings : {192.168.x.x:993} InternalConnectionSettings : {mail.office.domain.com:143:TLS, mail.office.domain.com:993:SSL} ExternalConnectionSettings : {mail.office.domain.com:143:TLS, mail.office.domain.com:993:SSL} X509CertificateName : mail.domain.com Banner : The Microsoft Exchange IMAP4 service is ready. LoginType : SecureLogin AuthenticatedConnectionTimeout : 00:30:00 PreAuthenticatedConnectionTimeout : 00:01:00 MaxConnections : 2147483647 MaxConnectionFromSingleIP : 2147483647 MaxConnectionsPerUser : 16 MessageRetrievalMimeFormat : BestBodyFormat ProxyTargetPort : 143 CalendarItemRetrievalOption : iCalendar OwaServerUrl : EnableExactRFC822Size : False LiveIdBasicAuthReplacement : False SuppressReadReceipt : False ProtocolLogEnabled : True EnforceCertificateErrors : False LogFileLocation : C:\Program Files\Microsoft\Exchange Server\V14\Logging\Imap4 LogFileRollOverSettings : Daily LogPerFileSizeQuota : 0 B (0 bytes) ExtendedProtectionPolicy : None EnableGSSAPIAndNTLMAuth : True Server : CMX-OFFICE-EX01 AdminDisplayName : ExchangeVersion : 0.10 (14.0.100.0) DistinguishedName : CN=1,CN=IMAP4,CN=Protocols,CN=EXCHANGE01,CN=Servers,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,CN=Our COmpany,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=domain,DC=com Identity : EXCHANGE01\1 Guid : 48f9dc37-74c2-4fb0-a042-641f863f45f2 ObjectCategory : domain.com/Configuration/Schema/ms-Exch-Protocol-Cfg-IMAP-Server ObjectClass : {top, protocolCfg, protocolCfgIMAP, protocolCfgIMAPServer} WhenChanged : 21/04/2011 17:03:39 WhenCreated : 15/04/2011 13:51:58 WhenChangedUTC : 21/04/2011 16:03:39 WhenCreatedUTC : 15/04/2011 12:51:58 OrganizationId : OriginatingServer : a-domain-server IsValid : True

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  • What is the worst programming language you ever worked with? [closed]

    - by Ludwig Weinzierl
    If you have an interesting story to share, please post an answer, but do not abuse this question for bashing a language. We are programmers, and our primary tool is the programming language we use. While there is a lot of discussion about the best one, I'd like to hear your stories about the worst programming languages you ever worked with and I'd like to know exactly what annoyed you. I'd like to collect this stories partly to avoid common pitfalls while designing a language (especially a DSL) and partly to avoid quirky languages in the future in general. This question is not subjective. If a language supports only single character identifiers (see my own answer) this is bad in a non-debatable way. EDIT Some people have raised concerns that this question attracts trolls. Wading through all your answers made one thing clear. The large majority of answers is appropriate, useful and well written. UPDATE 2009-07-01 19:15 GMT The language overview is now complete, covering 103 different languages from 102 answers. I decided to be lax about what counts as a programming language and included anything reasonable. Thank you David for your comments on this. Here are all programming languages covered so far (alphabetical order, linked with answer, new entries in bold): ABAP, all 20th century languages, all drag and drop languages, all proprietary languages, APF, APL (1), AS400, Authorware, Autohotkey, BancaStar, BASIC, Bourne Shell, Brainfuck, C++, Centura Team Developer, Cobol (1), Cold Fusion, Coldfusion, CRM114, Crystal Syntax, CSS, Dataflex 2.3, DB/c DX, dbase II, DCL, Delphi IDE, Doors DXL, DOS batch (1), Excel Macro language, FileMaker, FOCUS, Forth, FORTRAN, FORTRAN 77, HTML, Illustra web blade, Informix 4th Generation Language, Informix Universal Server web blade, INTERCAL, Java, JavaScript (1), JCL (1), karol, LabTalk, Labview, Lingo, LISP, Logo, LOLCODE, LotusScript, m4, Magic II, Makefiles, MapBasic, MaxScript, Meditech Magic, MEL, mIRC Script, MS Access, MUMPS, Oberon, object extensions to C, Objective-C, OPS5, Oz, Perl (1), PHP, PL/SQL, PowerDynamo, PROGRESS 4GL, prova, PS-FOCUS, Python, Regular Expressions, RPG, RPG II, Scheme, ScriptMaker, sendmail.conf, Smalltalk, Smalltalk , SNOBOL, SpeedScript, Sybase PowerBuilder, Symbian C++, System RPL, TCL, TECO, The Visual Software Environment, Tiny praat, TransCAD, troff, uBasic, VB6 (1), VBScript (1), VDF4, Vimscript, Visual Basic (1), Visual C++, Visual Foxpro, VSE, Webspeed, XSLT The answers covering 80386 assembler, VB6 and VBScript have been removed.

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  • How can I monitor if a cookie is being sent to a domain other than the one it originated from?

    - by Brendan Salt
    I am trying to write a program that will verify that all cookies sent out from the machine are in fact going to the domain they came from. This is part of a larger security project to detect cookie based malicious attacks (such as XSS). The main snag for this project is actually detecting the out-going cookies. Can someone point me in the right direction for monitoring out-going HTTP traffic for cookie information? Other information about the project: This is a windows application written in C and numerous scripting languages. Thanks so much for the help.

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  • Java AD Authentication across Trusted Domains

    - by benjiisnotcool
    I am trying to implement Active Directory authentication in Java which will be ran from a Linux machine. Our AD set-up will consist of multiple servers that share trust relationships with one another so for our test environment we have two domain controllers: test1.ad1.foo.com who trusts test2.ad2.bar.com. Using the code below I can successfully authenticate a user from test1 but not on test2: public class ADDetailsProvider implements ResultSetProvider { private String domain; private String user; private String password; public ADDetailsProvider(String user, String password) { //extract domain name if (user.contains("\\")) { this.user = user.substring((user.lastIndexOf("\\") + 1), user.length()); this.domain = user.substring(0, user.lastIndexOf("\\")); } else { this.user = user; this.domain = ""; } this.password = password; } /* Test from the command line */ public static void main (String[] argv) throws SQLException { ResultSetProvider res = processADLogin(argv[0], argv[1]); ResultSet results = null; res.assignRowValues(results, 0); System.out.println(argv[0] + " " + argv[1]); } public boolean assignRowValues(ResultSet results, int currentRow) throws SQLException { // Only want a single row if (currentRow >= 1) return false; try { ADAuthenticator adAuth = new ADAuthenticator(); LdapContext ldapCtx = adAuth.authenticate(this.domain, this.user, this.password); NamingEnumeration userDetails = adAuth.getUserDetails(ldapCtx, this.user); // Fill the result set (throws SQLException). while (userDetails.hasMoreElements()) { Attribute attr = (Attribute)userDetails.next(); results.updateString(attr.getID(), attr.get().toString()); } results.updateInt("authenticated", 1); return true; } catch (FileNotFoundException fnf) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught File Not Found Exception trying to read cris_authentication.properties"); results.updateInt("authenticated", 0); return false; } catch (IOException ioe) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught IO Excpetion processing login"); results.updateInt("authenticated", 0); return false; } catch (AuthenticationException aex) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught Authentication Exception attempting to bind to LDAP for [{0}]", this.user); results.updateInt("authenticated", 0); return true; } catch (NamingException ne) { Logger.getAnonymousLogger().log(Level.WARNING, "Caught Naming Exception performing user search or LDAP bind for [{0}]", this.user); results.updateInt("authenticated", 0); return true; } } public void close() { // nothing needed here } /** * This method is called via a Postgres function binding to access the * functionality provided by this class. */ public static ResultSetProvider processADLogin(String user, String password) { return new ADDetailsProvider(user, password); } } public class ADAuthenticator { public ADAuthenticator() throws FileNotFoundException, IOException { Properties props = new Properties(); InputStream inStream = this.getClass().getClassLoader(). getResourceAsStream("com/bar/foo/ad/authentication.properties"); props.load(inStream); this.domain = props.getProperty("ldap.domain"); inStream.close(); } public LdapContext authenticate(String domain, String user, String pass) throws AuthenticationException, NamingException, IOException { Hashtable env = new Hashtable(); this.domain = domain; env.put(Context.INITIAL_CONTEXT_FACTORY, com.sun.jndi.ldap.LdapCtxFactory); env.put(Context.PROVIDER_URL, "ldap://" + test1.ad1.foo.com + ":" + 3268); env.put(Context.SECURITY_AUTHENTICATION, simple); env.put(Context.REFERRAL, follow); env.put(Context.SECURITY_PRINCIPAL, (domain + "\\" + user)); env.put(Context.SECURITY_CREDENTIALS, pass); // Bind using specified username and password LdapContext ldapCtx = new InitialLdapContext(env, null); return ldapCtx; } public NamingEnumeration getUserDetails(LdapContext ldapCtx, String user) throws NamingException { // List of attributes to return from LDAP query String returnAttributes[] = {"ou", "sAMAccountName", "givenName", "sn", "memberOf"}; //Create the search controls SearchControls searchCtls = new SearchControls(); searchCtls.setReturningAttributes(returnAttributes); //Specify the search scope searchCtls.setSearchScope(SearchControls.SUBTREE_SCOPE); // Specify the user to search against String searchFilter = "(&(objectClass=*)(sAMAccountName=" + user + "))"; //Perform the search NamingEnumeration answer = ldapCtx.search("dc=dev4,dc=dbt,dc=ukhealth,dc=local", searchFilter, searchCtls); // Only care about the first tuple Attributes userAttributes = ((SearchResult)answer.next()).getAttributes(); if (userAttributes.size() <= 0) throw new NamingException(); return (NamingEnumeration) userAttributes.getAll(); } From what I understand of the trust relationship, if trust1 receives a login attempt for a user in trust2, then it should forward the login attempt on to it and it works this out from the user's domain name. Is this correct or am I missing something or is this not possible using the method above? --EDIT-- The stack trace from the LDAP bind is {java.naming.provider.url=ldap://test1.ad1.foo.com:3268, java.naming.factory.initial=com.sun.jndi.ldap.LdapCtxFactory, java.naming.security.authentication=simple, java.naming.referral=follow} 30-Oct-2012 13:16:02 ADDetailsProvider assignRowValues WARNING: Caught Authentication Exception attempting to bind to LDAP for [trusttest] Auth error is [LDAP: error code 49 - 80090308: LdapErr: DSID-0C0903A9, comment: AcceptSecurityContext error, data 52e, v1db0]

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  • If I use a facade class with generic methods to access the JPA API, how should I provide additional processing for specific types?

    - by Shaun
    Let's say I'm making a fairly simple web application using JAVA EE specs (I've heard this is possible). In this app, I only have about 10 domain/data objects, and these are represented by JPA Entities. Architecturally, I would consider the JPA API to perform the role of a DAO. Of course, I don't want to use the EntityManager directly in my UI (JSF) and I need to manage transactions, so I delegate these tasks to the so-called service layer. More specifically, I would like to be able to handle these tasks in a single DataService class (often also called CrudService) with generic methods. See this article by Adam Bien for an example interface: http://www.adam-bien.com/roller/abien/entry/generic_crud_service_aka_dao My project differs from that article in that I can't use EJBs, so my service classes are essentially just named beans and I handle transactions manually. Regardless, what I want is a single interface for simple CRUD operations on my data objects because having a different class for each data type would lead to a lot of duplicate and/or unnecessary code. Ideally, my views would be able to use a method such as public <T> List<T> findAll(Class<T> type) { ... } to retrieve data. Using JSF, it might look something like this: <h:dataTable value="#{dataService.findAll(data.class)}" var="d"> ... </h:dataTable> Similarly, after validating forms, my controller could submit the data with a method such as: public <T> void add(T entity) { ... } Granted, you'd probably actually want to return something useful to the caller. In any case, this works well if your data can be treated as homogenous in this manner. Alas, it breaks down when you need to perform additional processing on certain objects before passing them on to JPA. For example, let's say I'm dealing with Books and Authors which have a many-to-many relationship. Each Book has a set of IDs referring to its authors, and each Author has a set of IDs referring to their books. Normally, JPA can manage this kind of relationship for you, but in some cases it can't (for example, the google app engine JPA provider doesn't support this). Thus, when I persist a new book for example, I may need to update the corresponding author entities. My question, then, is if there's an elegant way to handle this or if I should reconsider the sanity of my whole design. Here's a couple ways I see of dealing with it: The instanceof operator. I could use this to target certain classes when special processing is needed. Perhaps maintainability suffers and it isn't beautiful code, but if there's only 10 or so domain objects it can't be all that bad... could it? Make a different service for each entity type (ie, BookService and AuthorService). All services would inherit from a generic DataService base class and override methods if special processing is needed. At this point, you could probably also just call them DAOs instead. As always, I appreciate the help. Let me know if any clarifications are needed, as I left out many smaller details.

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  • CQRS &ndash; Questions and Concerns

    - by Dylan Smith
    I’ve been doing a lot of learning on CQRS and Event Sourcing over the last little while and I have a number of questions that I haven’t been able to answer. 1. What is the benefit of CQRS when compared to a typical DDD architecture that uses Event Sourcing and properly captures intent and behavior via verb-based commands? (other than Scalability) 2. When using CQRS what do you do with complex query-based logic? I’m going to elaborate on #1 in this blog post and I’ll do a follow-up post on #2. I watched through Greg Young’s video on the business benefits of CQRS + Event Sourcing and first let me say that I thought it was an excellent presentation that really drives home a lot of the benefits to this approach to architecture (I watched it twice in a row I enjoyed it so much!). But it didn’t answer some of my questions fully (I wish I had been there to ask these of Greg in person!). So let me pick apart some of the points he makes and how they relate to my first question above. I’m completely sold on the idea of event sourcing and have a clear understanding of the benefits that it brings to the table, so I’m not going to question that. But you can use event sourcing without going to a CQRS architecture, so my main question is around the benefits of CQRS + Event Sourcing vs Event Sourcing + Typical DDD architecture Architecture with Event Sourcing + Commands on Left, CQRS on Right Greg talks about how the stereotypical architecture doesn’t support DDD, but is that only because his diagram shows DTO’s coming up from the client. If we use the same diagram but allow the client to send commands doesn’t that remove a lot of the arguments that Greg makes against the stereotypical architecture? We can now introduce verbs into the system. We can capture intent now (storing it still requires event sourcing, but you can implement event sourcing without doing CQRS) We can create a rich domain model (as opposed to an anemic domain model) Scalability is obviously a benefit that CQRS brings to the table, but like Greg says, very few of the systems we create truly need significant scalability Greg talks about the ability to scale your development efforts. He says CQRS allows you to split the system into 3 parts (Client, Domain/Commands, Reads) and assign 3 teams of developers to work on them in parallel; letting you scale your development efforts by 3x with nearly linear gains. But in the stereotypical architecture don’t you already have 2 separate modules that you can split your dev efforts between: The client that sends commands/queries and receives DTO’s, and the Domain which accepts commands/queries, and generates events/DTO’s. If this is true it’s not really a 3x scaling you achieve with CQRS but merely a 1.5x scaling which while great doesn’t sound nearly as dramatic (“I can do it with 10 devs in 12 months – let me hire 5 more and we can have it done in 8 months”). Making the Query side “stupid simple” such that you can assign junior developers (or even outsource it) sounds like a valid benefit, but I have some concerns over what you do with complex query-based logic/behavior. I’m going to go into more detail on this in a follow-up blog post shortly. He also seemed to focus on how “stupid-simple” it is doing queries against the de-normalized data store, but I imagine there is still significant complexity in the event handlers that interpret the events and apply them to the de-normalized tables. It sounds like Greg suggests that because we’re doing CQRS that allows us to apply Event Sourcing when we otherwise wouldn’t be able to (~33:30 in the video). I don’t believe this is true. I don’t see why you wouldn’t be able to apply Event Sourcing without separating out the Commands and Queries. The queries would just operate against the domain model instead of the database. But you’d still get the benefits of Event Sourcing. Without CQRS the queries would only be able to operate against the current state rather than the event history, but even in CQRS the domain behaviors can only operate against the current state and I don’t see that being a big limiting factor. If some query needs to operate against something that is not captured by the current state you would just have to update the domain model to capture that information (no different than if that statement were made about a Command under CQRS). Some of the benefits I do see being applicable are that your domain model might end up being simpler/smaller since it only needs to represent the state needed to process commands and not worry about the reads (like the Deactivate Inventory Item and associated comment example that Greg provides). And also commands that can be handled in a Transaction Script style manner by the command handler simply generating events and not touching the domain model. It also makes it easier for your senior developers to focus on the command behavior and ignore the queries, which is usually going to be a better use of their time. And of course scalability. If anybody out there has any thoughts on this and can help educate me further, please either leave a comment or feel free to get in touch with me via email:

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  • Will adding q&a help my site's rankings, and if so, what are the implications of a sub-domain for q&a rather than a path on the site? [closed]

    - by ElHaix
    Possible Duplicate: Subdomain versus subdirectory One of our web properties is doing quite well without any additional links being created on the site, and our link inventory is tightly managed - no user-generated links. To introduce a community aspect to the site, we want to implement a q&a forum. Once in place, new links will populate our link inventory with keywords that are not necessarily targeted to the site. With the q&a on a sub-domain, would that not affect the main site's rankings? What's the best approach for this?

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