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• Multiple file access in groovy(Groovy on Grails)

  - by Anthony Umpad

  Hello, I have an application that allows multiple users to access 1 xml file. The problem is that when all the users save at once the other changes by other users does not get saved. How do I detect if the file is in user in groovy? Thanks!

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• Is Berkeley DB a NoSQL solution?

  - by Gregory Burd

  Berkeley DB is a library. To use it to store data you must link the library into your application. You can use most programming languages to access the API, the calls across these APIs generally mimic the Berkeley DB C-API which makes perfect sense because Berkeley DB is written in C. The inspiration for Berkeley DB was the DBM library, a part of the earliest versions of UNIX written by AT&T's Ken Thompson in 1979. DBM was a simple key/value hashtable-based storage library. In the early 1990s as BSD UNIX was transitioning from version 4.3 to 4.4 and retrofitting commercial code owned by AT&T with unencumbered code, it was the future founders of Sleepycat Software who wrote libdb (aka Berkeley DB) as the replacement for DBM. The problem it addressed was fast, reliable local key/value storage. At that time databases almost always lived on a single node, even the most sophisticated databases only had simple fail-over two node solutions. If you had a lot of data to store you would choose between the few commercial RDBMS solutions or to write your own custom solution. Berkeley DB took the headache out of the custom approach. These basic market forces inspired other DBM implementations. There was the "New DBM" (ndbm) and the "GNU DBM" (GDBM) and a few others, but the theme was the same. Even today TokyoCabinet calls itself "a modern implementation of DBM" mimicking, and improving on, something first created over thirty years ago. In the mid-1990s, DBM was the name for what you needed if you were looking for fast, reliable local storage. Fast forward to today. What's changed? Systems are connected over fast, very reliable networks. Disks are cheep, fast, and capable of storing huge amounts of data. CPUs continued to follow Moore's Law, processing power that filled a room in 1990 now fits in your pocket. PCs, servers, and other computers proliferated both in business and the personal markets. In addition to the new hardware entire markets, social systems, and new modes of interpersonal communication moved onto the web and started evolving rapidly. These changes cause a massive explosion of data and a need to analyze and understand that data. Taken together this resulted in an entirely different landscape for database storage, new solutions were needed. A number of novel solutions stepped up and eventually a category called NoSQL emerged. The new market forces inspired the CAP theorem and the heated debate of BASE vs. ACID. But in essence this was simply the market looking at what to trade off to meet these new demands. These new database systems shared many qualities in common. There were designed to address massive amounts of data, millions of requests per second, and scale out across multiple systems. The first large-scale and successful solution was Dynamo, Amazon's distributed key/value database. Dynamo essentially took the next logical step and added a twist. Dynamo was to be the database of record, it would be distributed, data would be partitioned across many nodes, and it would tolerate failure by avoiding single points of failure. Amazon did this because they recognized that the majority of the dynamic content they provided to customers visiting their web store front didn't require the services of an RDBMS. The queries were simple, key/value look-ups or simple range queries with only a few queries that required more complex joins. They set about to use relational technology only in places where it was the best solution for the task, places like accounting and order fulfillment, but not in the myriad of other situations. The success of Dynamo, and it's design, inspired the next generation of Non-SQL, distributed database solutions including Cassandra, Riak and Voldemort. The problem their designers set out to solve was, "reliability at massive scale" so the first focal point was distributed database algorithms. Underneath Dynamo there is a local transactional database; either Berkeley DB, Berkeley DB Java Edition, MySQL or an in-memory key/value data structure. Dynamo was an evolution of local key/value storage onto networks. Cassandra, Riak, and Voldemort all faced similar design decisions and one, Voldemort, choose Berkeley DB Java Edition for it's node-local storage. Riak at first was entirely in-memory, but has recently added write-once, append-only log-based on-disk storage similar type of storage as Berkeley DB except that it is based on a hash table which must reside entirely in-memory rather than a btree which can live in-memory or on disk. Berkeley DB evolved too, we added high availability (HA) and a replication manager that makes it easy to setup replica groups. Berkeley DB's replication doesn't partitioned the data, every node keeps an entire copy of the database. For consistency, there is a single node where writes are committed first - a master - then those changes are delivered to the replica nodes as log records. Applications can choose to wait until all nodes are consistent, or fire and forget allowing Berkeley DB to eventually become consistent. Berkeley DB's HA scales-out quite well for read-intensive applications and also effectively eliminates the central point of failure by allowing replica nodes to be elected (using a PAXOS algorithm) to mastership if the master should fail. This implementation covers a wide variety of use cases. MemcacheDB is a server that implements the Memcache network protocol but uses Berkeley DB for storage and HA to replicate the cache state across all the nodes in the cache group. Google Accounts, the user authentication layer for all Google properties, was until recently running Berkeley DB HA. That scaled to a globally distributed system. That said, most NoSQL solutions try to partition (shard) data across nodes in the replication group and some allow writes as well as reads at any node, Berkeley DB HA does not. So, is Berkeley DB a "NoSQL" solution? Not really, but it certainly is a component of many of the existing NoSQL solutions out there. Forgetting all the noise about how NoSQL solutions are complex distributed databases when you boil them down to a single node you still have to store the data to some form of stable local storage. DBMs solved that problem a long time ago. NoSQL has more to do with the layers on top of the DBM; the distributed, sometimes-consistent, partitioned, scale-out storage that manage key/value or document sets and generally have some form of simple HTTP/REST-style network API. Does Berkeley DB do that? Not really. Is Berkeley DB a "NoSQL" solution today? Nope, but it's the most robust solution on which to build such a system. Re-inventing the node-local data storage isn't easy. A lot of people are starting to come to appreciate the sophisticated features found in Berkeley DB, even mimic them in some cases. Could Berkeley DB grow into a NoSQL solution? Absolutely. Our key/value API could be extended over the net using any of a number of existing network protocols such as memcache or HTTP/REST. We could adapt our node-local data partitioning out over replicated nodes. We even have a nice query language and cost-based query optimizer in our BDB XML product that we could reuse were we to build out a document-based NoSQL-style product. XML and JSON are not so different that we couldn't adapt one to work with the other interchangeably. Without too much effort we could add what's missing, we could jump into this No SQL market withing a single product development cycle. Why isn't Berkeley DB already a NoSQL solution? Why aren't we working on it? Why indeed...

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• mysql encoding problem

  - by Syom

  i have a proble, when insert something in foreign language into database. i have set the collation of database to utf8_general_ci(try utf8_unicod_ci too). but when i insert some text into table, it was saved like this Õ€Õ¡ÕµÕ¥Ö€Õ¥Õ¶ Ô±Õ¶Õ¸Ö‚Õ¶ but when i read from database, text shows in correct form. it looks like that only in database. i have set encoding in my html document to charset=UTF-8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> and i set mysql_query("SET NAMES UTF-8"); mysql_query("SET CHARACTER SET UTF-8"); when conecting to database. so i think that i' ve done everything, but it still save in that anknown format. could you help me. thanks in advance

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• JavaEE in netbeans giving BUILD FAILED error upon deployment

  - by user312402

  When I try to run my Java EE program in Netbeans consisting of servlets (java pages), JSP's, beans(java pages) and HTML pages I get this error in the output: In-place deployment at C:\Users\Derek\Documents\NetBeansProjects\EJBProject\EJBProject-war\build\web Initializing... deploy?path=C:\Users\Derek\Documents\NetBeansProjects\EJBProject\EJBProject-war\build\web&name=EJBProject-war&force=true failed on Personal GlassFish v3 Domain C:\Users\Derek\Documents\NetBeansProjects\EJBProject\EJBProject-war\nbproject\build-impl.xml:611: The module has not been deployed. BUILD FAILED (total time: 1 second) And then in the command prompt when I run asant run in the appropriate directory, I get: C:\Users\Derek\Documents\NetBeansProjects\EJBProject\nbproject\build-impl.xml:19: Class org.apache.tools.ant.taskdefs.condition.Not doesn't support the nested "antversion" element. Do you know why this would be? Why won't netbeans deploy my application so I can run and test it?

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• How can I reliably check client identity whilst making DCOM calls to a C# .Net 3.5 Server?

  - by pionium

  Hi, I have an old Win32 C++ DCOM Server that I am rewriting to use C# .Net 3.5. The client applications sit on remote XP machines and are also written in C++. These clients must remain unchanged, hence I must implement the interfaces on new .Net objects. This has been done, and is working successfully regarding the implementation of the interfaces, and all of the calls are correctly being made from the old clients to the new .Net objects. However, I'm having problems obtaining the identity of the calling user from the DCOM Client. In order to try to identify the user who instigated the DCOM call, I have the following code on the server... [DllImport("ole32.dll")] static extern int CoImpersonateClient(); [DllImport("ole32.dll")] static extern int CoRevertToSelf(); private string CallingUser { get { string sCallingUser = null; if (CoImpersonateClient() == 0) { WindowsPrincipal wp = System.Threading.Thread.CurrentPrincipal as WindowsPrincipal; if (wp != null) { WindowsIdentity wi = wp.Identity as WindowsIdentity; if (wi != null && !string.IsNullOrEmpty(wi.Name)) sCallingUser = wi.Name; } if (CoRevertToSelf() != 0) ReportWin32Error("CoRevertToSelf"); } else ReportWin32Error("CoImpersonateClient"); return sCallingUser; } } private static void ReportWin32Error(string sFailingCall) { Win32Exception ex = new Win32Exception(); Logger.Write("Call to " + sFailingCall + " FAILED: " + ex.Message); } When I get the CallingUser property, the value returned the first few times is correct and the correct user name is identified, however, after 3 or 4 different users have successfully made calls (and it varies, so I can't be more specific), further users seem to be identified as users who had made earlier calls. What I have noticed is that the first few users have their DCOM calls handled on their own thread (ie all calls from a particular client are handled by a single unique thread), and then subsequent users are being handled by the same threads as the earlier users, and after the call to CoImpersonateClient(), the CurrentPrincipal matches that of the initial user of that thread. To Illustrate: User Tom makes DCOM calls which are handled by thread 1 (CurrentPrincipal correctly identifies Tom) User Dick makes DCOM calls which are handled by thread 2 (CurrentPrincipal correctly identifies Dick) User Harry makes DCOM calls which are handled by thread 3 (CurrentPrincipal correctly identifies Harry) User Bob makes DCOM calls which are handled by thread 3 (CurrentPrincipal incorrectly identifies him as Harry) As you can see in this illustration, calls from clients Harry and Bob are being handled on thread 3, and the server is identifying the calling client as Harry. Is there something that I am doing wrong? Are there any caveats or restrictions on using Impersonations in this way? Is there a better or different way that I can RELIABLY achieve what I am trying to do? All help would be greatly appreciated. Regards Andrew

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• Connection Pooling is Busted

  - by MightyZot

  A few weeks ago we started getting complaints about performance in an application that has performed very well for many years.  The application is a n-tier application that uses ADODB with the SQLOLEDB provider to talk to a SQL Server database.  Our object model is written in such a way that each public method validates security before performing requested actions, so there is a significant number of queries executed to get information about file cabinets, retrieve images, create workflows, etc.  (PaperWise is a document management and workflow system.)  A common factor for these customers is that they have remote offices connected via MPLS networks. Naturally, the first thing we looked at was the query performance in SQL Profiler.  All of the queries were executing within expected timeframes, most of them were so fast that the duration in SQL Profiler was zero.  After getting nowhere with SQL Profiler, the situation was escalated to me.  I decided to take a peek with Process Monitor.  Procmon revealed some “gaps” in the TCP/IP traffic.  There were notable delays between send and receive pairs.  The send and receive pairs themselves were quite snappy, but quite often there was a notable delay between a receive and the next send.  You might expect some delay because, presumably, the application is doing some thinking in-between the pairs.  But, comparing the procmon data at the remote locations with the procmon data for workstations on the local network showed that the remote workstations were significantly delayed.  Procmon also showed a high number of disconnects. Wireshark traces showed that connections to the database were taking between 75ms and 150ms.  Not only that, but connections to a file share containing images were taking 2 seconds!  So, I asked about a trust.  Sure enough there was a trust between two domains and the file share was on the second domain.  Joining a remote workstation to the domain hosting the share containing images alleviated the time delay in accessing the file share.  Removing the trust had no affect on the connections to the database. Microsoft Network Monitor includes filters that parse TDS packets.  TDS is the protocol that SQL Server uses to communicate.  There is a certificate exchange and some SSL that occurs during authentication.  All of this was evident in the network traffic.  After staring at the network traffic for a while, and examining packets, I decided to call it a night.  On the way home that night, something about the traffic kept nagging at me.  Then it dawned on me…at the beginning of the dance of packets between the client and the server all was well.  Connection pooling was working and I could see multiple queries getting executed on the same connection and ethereal port.  After a particular query, connecting to two different servers, I noticed that ADODB and SQLOLEDB started making repeated connections to the database on different ethereal ports.  SQL Server would execute a single query and respond on a port, then open a new port and execute the next query.  Connection pooling appeared to be broken. The next morning I wrote a test to confirm my hypothesis.  Turns out that the sequence causing the connection nastiness goes something like this: Make a connection to the database. Open a result set that returns enough records to require multiple roundtrips to the server. For each result, query for some other data in the database (this will open a new implicit connection.) Close the inner result set and repeat for every item in the original result set. Close the original connection. Provided that the first result set returns enough data to require multiple roundtrips to the server, ADODB and SQLOLEDB will start making new connections to the database for each query executed in the loop.  Originally, I thought this might be due to Microsoft’s denial of service (ddos) attack protection.  After turning those features off to no avail, I eventually thought to switch my queries to client-side cursors instead of server-side cursors.  Server-side cursors are the default, by the way.  Voila!  After switching to client-side cursors, the disconnects were gone and the above sequence yielded two connections as expected. While the real problem is the amount of time it takes to make connections over these MPLS networks (100ms on average), switching to client-side cursors made the problem go away.  Believe it or not, this is actually documented by Microsoft, and rather difficult to find.  (At least it was while we were trying to troubleshoot the problem!)  So, if you’re noticing performance issues on slower networks, or networks with slower switching, take a look at the traffic in a tool like Microsoft Network Monitor.  If you notice a high number of disconnects, and you’re using fire-hose or server-side cursors, then try switching to client-side cursors and you may see the problem go away. Most likely, Microsoft believes this to be appropriate behavior, because ADODB can’t guarantee that all of the data has been retrieved when you execute the inner queries.  I’m not convinced, though, because the problem remains even after replacing all of the implicit connections with explicit connections and closing those connections in-between each of the inner queries.  In that case, there doesn’t seem to be a reason why ADODB can’t use a single connection from the connection pool to make the additional queries, bringing the total number of connections to two.  Instead ADO appears to make an assumption about the state of the connection. I’ve reported the behavior to Microsoft and am awaiting to hear from the appropriate team, so that I can demonstrate the problem.  Maybe they can explain to us why this is appropriate behavior.  :)

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• Thinking Sphinx not working in test mode

  - by J. Pablo Fernández

  I'm trying to get Thinking Sphinx to work in test mode in Rails. Basically this: ThinkingSphinx::Test.init ThinkingSphinx::Test.start freezes and never comes back. My test and devel configuration is the same for test and devel: dry_setting: &dry_setting adapter: mysql host: localhost encoding: utf8 username: rails password: blahblah development: <<: *dry_setting database: proj_devel socket: /tmp/mysql.sock # sphinx requires it test: <<: *dry_setting database: proj_test socket: /tmp/mysql.sock # sphinx requires it and sphinx.yml development: enable_star: 1 min_infix_len: 2 bin_path: /opt/local/bin test: enable_star: 1 min_infix_len: 2 bin_path: /opt/local/bin production: enable_star: 1 min_infix_len: 2 The generated config files, config/development.sphinx.conf and config/test.sphinx.conf only differ in database names, directories and similar things; nothing functional. Generating the index for devel goes without an issue $ rake ts:in (in /Users/pupeno/proj) default config Generating Configuration to /Users/pupeno/proj/config/development.sphinx.conf Sphinx 0.9.8.1-release (r1533) Copyright (c) 2001-2008, Andrew Aksyonoff using config file '/Users/pupeno/proj/config/development.sphinx.conf'... indexing index 'user_core'... collected 7 docs, 0.0 MB collected 0 attr values sorted 0.0 Mvalues, 100.0% done sorted 0.0 Mhits, 99.8% done total 7 docs, 422 bytes total 0.098 sec, 4320.80 bytes/sec, 71.67 docs/sec indexing index 'user_delta'... collected 0 docs, 0.0 MB collected 0 attr values sorted 0.0 Mvalues, nan% done total 0 docs, 0 bytes total 0.010 sec, 0.00 bytes/sec, 0.00 docs/sec distributed index 'user' can not be directly indexed; skipping. but when I try to do it for test it freezes: $ RAILS_ENV=test rake ts:in (in /Users/pupeno/proj) DEPRECATION WARNING: require "activeresource" is deprecated and will be removed in Rails 3. Use require "active_resource" instead.. (called from /Users/pupeno/.rvm/gems/ruby-1.8.7-p249/gems/activeresource-2.3.5/lib/activeresource.rb:2) default config Generating Configuration to /Users/pupeno/proj/config/test.sphinx.conf Sphinx 0.9.8.1-release (r1533) Copyright (c) 2001-2008, Andrew Aksyonoff using config file '/Users/pupeno/proj/config/test.sphinx.conf'... indexing index 'user_core'... It's been there for more than 10 minutes, the user table has 4 records. The database directory look quite diferently, but I don't know what to make of it: $ ls -l db/sphinx/development/ total 96 -rw-r--r-- 1 pupeno staff 196 Mar 11 18:10 user_core.spa -rw-r--r-- 1 pupeno staff 4982 Mar 11 18:10 user_core.spd -rw-r--r-- 1 pupeno staff 417 Mar 11 18:10 user_core.sph -rw-r--r-- 1 pupeno staff 3067 Mar 11 18:10 user_core.spi -rw-r--r-- 1 pupeno staff 84 Mar 11 18:10 user_core.spm -rw-r--r-- 1 pupeno staff 6832 Mar 11 18:10 user_core.spp -rw-r--r-- 1 pupeno staff 0 Mar 11 18:10 user_delta.spa -rw-r--r-- 1 pupeno staff 1 Mar 11 18:10 user_delta.spd -rw-r--r-- 1 pupeno staff 417 Mar 11 18:10 user_delta.sph -rw-r--r-- 1 pupeno staff 1 Mar 11 18:10 user_delta.spi -rw-r--r-- 1 pupeno staff 0 Mar 11 18:10 user_delta.spm -rw-r--r-- 1 pupeno staff 1 Mar 11 18:10 user_delta.spp $ ls -l db/sphinx/test/ total 0 -rw-r--r-- 1 pupeno staff 0 Mar 11 18:11 user_core.spl -rw-r--r-- 1 pupeno staff 0 Mar 11 18:11 user_core.tmp0 -rw-r--r-- 1 pupeno staff 0 Mar 11 18:11 user_core.tmp1 -rw-r--r-- 1 pupeno staff 0 Mar 11 18:11 user_core.tmp2 -rw-r--r-- 1 pupeno staff 0 Mar 11 18:11 user_core.tmp7 Nothing gets added to a log when this happens. Any ideas where to go from here? I can run the command line manually: /opt/local/bin/indexer --config config/test.sphinx.conf --all which generates the output as the rake ts:in, so no help there.

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• Hello With Oracle Identity Manager Architecture

  - by mustafakaya

  Hi, my name is Mustafa! I'm a Senior Consultant in Fusion Middleware Team and living in Istanbul,Turkey. I worked many various Java based software development projects such as end-to-end web applications, CRM , Telco VAS and integration projects.I want to share my experiences and research about Fusion Middleware Products in this column. Customer always wants best solution from software consultants or developers. Solution will be a code snippet or change complete architecture. We faced different requests according to the case of customer. In my posts i want to discuss Fusion Middleware Products Architecture or how can extend usability with apis or UI customization and more and I look forward to engaging with you on your experiences and thoughts on this.  In my first post, i will be discussing Oracle Identity Manager architecture  and i plan to discuss Oracle Identity Manager 11g features in next posts. Oracle Identity Manager System Architecture Oracle Identity Governance includes Oracle Identity Manager,Oracle Identity Analytics and Oracle Privileged Account Manager. I will discuss Oracle Identity Manager architecture in this post.  In basically, Oracle Identity Manager is a n-tier standard  Java EE application that is deployed on Oracle WebLogic Server and uses  a database .  Oracle Identity Manager presentation tier has three different screen and two different client. Identity Self Service and Identity System Administration are web-based thin client. Design Console is a Java Swing Client that communicates directly with the Business Service Tier.  Identity Self Service provides end-user operations and delegated administration features. System Administration provides system administration functions. And Design Console mostly use for development management operations such as  create and manage adapter and process form,notification , workflow desing, reconciliation rules etc. Business service tier is implemented as an Enterprise JavaBeans(EJB) application. So you can extense Oracle Identity Manager capabilities.  -The SMPL and EJB APIs allow develop custom plug-ins such as management roles or identities.  -Identity Services allow use core business capabilites of Oracle Identity Manager such as The User provisioning or reconciliation service. -Integration Services allow develop custom connectors or adapters for various deployment needs. -Platform Services allow use Entitlement Servers, Scheduler or SOA composites. The Middleware tier allows you using capabilites ADF Faces,SOA Suites, Scheduler, Entitlement Server and BI Publisher Reports. So OIM allows you to configure workflows uses Oracle SOA Suite or define authorization policies use with Oracle Entitlement Server. Also you can customization of OIM UI without need to write code and using ADF Business Editor  you can extend custom attributes to user,role,catalog and other objects. Data tiers; Oracle Identity Manager is driven by data and metadata which provides flexibility and adaptability to Oracle Identity Manager functionlities.  -Database has five schemas these are OIM,SOA,MDS,OPSS and OES. Oracle Identity Manager uses database to store runtime and configuration data. And all of entity, transactional and audit datas are stored in database. -Metadata Store; customizations and personalizations are stored in file-based repository or database-based repository.And Oracle Identity Manager architecture,the metadata is in Oracle Identity Manager database to take advantage of some of the advanced performance and availability features that this mode provides. -Identity Store; Oracle Identity Manager provides the ability to integrate an LDAP-based identity store into Oracle Identity Manager architecture.  Oracle Identity Manager uses the human workflow module of Oracle Service Oriented Architecture Suite. OIM connects to SOA using the T3 URL which is front-end URL for the SOA server.Oracle Identity Manager uses embedded Oracle Entitlement Server for authorization checks in OIM engine.  Several Oracle Identity Manager modules use JMS queues. Each queue is processed by a separate Message Driven Bean (MDB), which is also part of the Oracle Identity Manager application. Message producers are also part of the Oracle Identity Manager application. Oracle Identity Manager uses a scheduled jobs for some activities in the background.Some of scheduled jobs come with Out-Of-Box such as the disable users after the end date of the users or you can define your custom schedule jobs with Oracle Identity Manager APIs. You can use Oracle BI Publisher for reporting Oracle Identity Manager transactions or audit data which are in database. About me: Mustafa Kaya is a Senior Consultant in Oracle Fusion Middleware Team, living in Istanbul. Before coming to Oracle, he worked in teams developing web applications and backend services at a telco company. He is a Java technology enthusiast, software engineer and addicted to learn new technologies,develop new ideas. Follow Mustafa on Twitter,Connect on LinkedIn, and visit his site for Oracle Fusion Middleware related tips.

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• SQL SERVER – A Quick Look at Logging and Ideas around Logging

  - by pinaldave

  This blog post is written in response to the T-SQL Tuesday post on Logging. When someone talks about logging, personally I get lots of ideas about it. I have seen logging as a very generic term. Let me ask you this question first before I continue writing about logging. What is the first thing comes to your mind when you hear word “Logging”? Now ask the same question to the guy standing next to you. I am pretty confident that you will get  a different answer from different people. I decided to do this activity and asked 5 SQL Server person the same question. Question: What is the first thing comes to your mind when you hear the word “Logging”? Strange enough I got a different answer every single time. Let me just list what answer I got from my friends. Let us go over them one by one. Output Clause The very first person replied output clause. Pretty interesting answer to start with. I see what exactly he was thinking. SQL Server 2005 has introduced a new OUTPUT clause. OUTPUT clause has access to inserted and deleted tables (virtual tables) just like triggers. OUTPUT clause can be used to return values to client clause. OUTPUT clause can be used with INSERT, UPDATE, or DELETE to identify the actual rows affected by these statements. Here are some references for Output Clause: OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE Reasons for Using Output Clause – Quiz Tips from the SQL Joes 2 Pros Development Series – Output Clause in Simple Examples Error Logs I was expecting someone to mention Error logs when it is about logging. The error log is the most looked place when there is any error either with the application or there is an error with the operating system. I have kept the policy to check my server’s error log every day. The reason is simple – enough time in my career I have figured out that when I am looking at error logs I find something which I was not expecting. There are cases, when I noticed errors in the error log and I fixed them before end user notices it. Other common practices I always tell my DBA friends to do is that when any error happens they should find relevant entries in the error logs and document the same. It is quite possible that they will see the same error in the error log  and able to fix the error based on the knowledge base which they have created. There can be many different kinds of error log files exists in SQL Server as well – 1) SQL Server Error Logs 2) Windows Event Log 3) SQL Server Agent Log 4) SQL Server Profile Log 5) SQL Server Setup Log etc. Here are some references for Error Logs: Recycle Error Log – Create New Log file without Server Restart SQL Error Messages Change Data Capture I got surprised with this answer. I think more than the answer I was surprised by the person who had answered me this one. I always thought he was expert in HTML, JavaScript but I guess, one should never assume about others. Indeed one of the cool logging feature is Change Data Capture. Change Data Capture records INSERTs, UPDATEs, and DELETEs applied to SQL Server tables, and makes a record available of what changed, where, and when, in simple relational ‘change tables’ rather than in an esoteric chopped salad of XML. These change tables contain columns that reflect the column structure of the source table you have chosen to track, along with the metadata needed to understand the changes that have been made. Here are some references for Change Data Capture: Introduction to Change Data Capture (CDC) in SQL Server 2008 Tuning the Performance of Change Data Capture in SQL Server 2008 Download Script of Change Data Capture (CDC) CDC and TRUNCATE – Cannot truncate table because it is published for replication or enabled for Change Data Capture Dynamic Management View (DMV) I like this answer. If asked I would have not come up with DMV right away but in the spirit of the original question, I think DMV does log the data. DMV logs or stores or records the various data and activity on the SQL Server. Dynamic management views return server state information that can be used to monitor the health of a server instance, diagnose problems, and tune performance. One can get plethero of information from DMVs – High Availability Status, Query Executions Details, SQL Server Resources Status etc. Here are some references for Dynamic Management View (DMV): SQL SERVER – Denali – DMV Enhancement – sys.dm_exec_query_stats – New Columns DMV – sys.dm_os_windows_info – Information about Operating System DMV – sys.dm_os_wait_stats Explanation – Wait Type – Day 3 of 28 DMV sys.dm_exec_describe_first_result_set_for_object – Describes the First Result Metadata for the Module Transaction Log Impact Detection Using DMV – dm_tran_database_transactions Log Files I almost flipped with this final answer from my friend. This should be probably the first answer. Yes, indeed log file logs the SQL Server activities. One can write infinite things about log file. SQL Server uses log file with the extension .ldf to manage transactions and maintain database integrity. Log file ensures that valid data is written out to database and system is in a consistent state. Log files are extremely useful in case of the database failures as with the help of full backup file database can be brought in the desired state (point in time recovery is also possible). SQL Server database has three recovery models – 1) Simple, 2) Full and 3) Bulk Logged. Each of the model uses the .ldf file for performing various activities. It is very important to take the backup of the log files (along with full backup) as one never knows when backup of the log file come into the action and save the day! How to Stop Growing Log File Too Big Reduce the Virtual Log Files (VLFs) from LDF file Log File Growing for Model Database – model Database Log File Grew Too Big master Database Log File Grew Too Big SHRINKFILE and TRUNCATE Log File in SQL Server 2008 Can I just say I loved this month’s T-SQL Tuesday Question. It really provoked very interesting conversation around me. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• GetAllUsers - MVC

  - by Jemes

  I’m using the Membership Provider and would like to display a list of all the users and their First Name, Last Name etc using the GetAllUsers function. I'm having trouble understanding how to implement this function in MVC. Has anyone implemented this in MVC or is there an easier way to list all the users in my application? Any help or advise would be really helpful. Controller public ActionResult GetUsers() { var users = Membership.GetAllUsers(); return View(users); } View Model public class GetUsers { [Required] [DisplayName("User name")] public string UserName { get; set; } [Required] [DisplayName("User name")] public string FirstName { get; set; } } View <%= Html.Encode(item.UserName) %> Error The model item passed into the dictionary is of type 'System.Web.Security.MembershipUserCollection', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[Account.Models.GetUsers]'.

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• How to check whether a user belongs to an AD group and nested groups?

  - by elsharpo

  hi guys, I have an ASP.NET 3.5 application using Windows Authentication and implementing our own RoleProvider. Problem is we want to restrict access to a set of pages to a few thousand users and rathern than inputing all of those one by one we found out they belong to an AD group. The answer is simple if the common group we are checking membership against the particular user is a direct member of it but the problem I'm having is that if the group is a member of another group and then subsequently member of another group then my code always returns false. For example: Say we want to check whether User is a member of group E, but User is not a direct member of *E", she is a member of "A" which a member of "B" which indeed is a member of E, therefore User is a member of *E" One of the solutions we have is very slow, although it gives the correct answer using (var context = new PrincipalContext(ContextType.Domain)) { using (var group = GroupPrincipal.FindByIdentity(context, IdentityType.Name, "DL-COOL-USERS")) { var users = group.GetMembers(true); // recursively enumerate return users.Any(a => a.Name == "userName"); } } The original solution and what I was trying to get to work, using .NET 3.5 System.DirectoryServices.AccountManagement and it does work when users are direct members of the group in question is as follows: public bool IsUserInGroup(string userName, string groupName) { var cxt = new PrincipalContext(ContextType.Domain, "DOMAIN"); var user = UserPrincipal.FindByIdentity(cxt, IdentityType.SamAccountName, userName); if (user == null) { return false; } var group = GroupPrincipal.FindByIdentity(cxt, groupName); if (group == null) { return false; } return user.IsMemberOf(group); } The bottom line is, we need to check for membership even though the groups are nested in many levels down. Thanks a lot!

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• Expose url to webservice

  - by Patrick Peters

  In our project we want to query a document management system for a specific document or movie. The dms returns a URL with the document location (for example: http://mydomain.myserver1.share/mypdf.pdf or http://mydomain.myserver2.share/mymovie.avi). We want to expose the document to internet users and intranet users. The requested file can be large (large video files). Our architecture is like: request goes like: webapp1 - webapp2 - webapp3 - dms response goes like: dms - webapp3 - webapp2 - webapp1 webapp1 could be on the internet. I have have been thinking how we can obfusicate the real url from the dms, due to security issues. I have seen implementations from other webapps where the pdf URL was obfusicated by creating a temp file for the requested document that is specific for the session and user. So other users cannot easily guess the documentname of other users. My question: is there a pattern that deals with exposing company/user vulernable data to the public ? Our development is in C# 3.5.

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• Asp.net override Membership settings at runtime (asp.net mvc)

  - by minal

  I had an application that hooked onto 1 single database. The app now needs to hook into multiple databases. What we want to do is, using the same application/domain/hostname/virtual dir give the user the option on the login screen to select the "App/Database" they want to connect into. Each database has the App tables/data/procs/etc as well as the aspnet membership/roles stuff. When the user enters the username/password and selects (select list) the application, I want to validate the user against the selected applications database. Presently the database connection string for membership services is saved in the web.config. Is there any way I can override this at login time? Also, I need the "remember me" function to work smoothly as well. How does this work when the user comes back to the app in 5 hours... This process should be able to identify the user and application and log in appropriately.

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• Using DevIL with Xcode

  - by jak3t

  Hello everyone! I'm trying to use DevIL with XCode but I can't get it to work. I tried using the "standard" method by doing "configure make make install" and using #import <IL/il> but it doesn't work. It identifies the library but I still get some compiling errors: Ld build/Release/cg.app/Contents/MacOS/cg normal i386 cd "/Users/simaorfreitas/Documents/LESI/3º ano/CG/CGaula1" /Developer/usr/bin/g++-4.2 -arch i386 "-L/Users/simaorfreitas/Documents/LESI/3º ano/CG/CGaula1/build/Release" "-F/Users/simaorfreitas/Documents/LESI/3º ano/CG/CGaula1/build/Release" -filelist "/Users/simaorfreitas/Documents/LESI/3º ano/CG/CGaula1/build/CGaula1.build/Release/cg.build/Objects-normal/i386/cg.LinkFileList" -framework Foundation -framework AppKit -framework GLUT -framework OpenGL -framework Cocoa -framework AppKit -o "/Users/simaorfreitas/Documents/LESI/3º ano/CG/CGaula1/build/Release/cg.app/Contents/MacOS/cg" Undefined symbols: "_ilConvertImage", referenced from: terreno() in main.o "_ilGetInteger", referenced from: terreno() in main.o terreno() in main.o terreno() in main.o "_ilLoadImage", referenced from: terreno() in main.o "_ilBindImage", referenced from: terreno() in main.o "_ilGetData", referenced from: terreno() in main.o "_ilInit", referenced from: terreno() in main.o "_ilGenImages", referenced from: terreno() in main.o ld: symbol(s) not found collect2: ld returned 1 exit status` So i tried do it by using the macports libdevil install. It installed correctly but nothing seems to work. Do I need to change my #import declarations? Any suggestion to install DevIL on the Mac correctly and use it in a XCode Project? Thanks a lot!

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• practical security ramifications of increasing WCF clock skew to more than an hour

  - by Andrew Patterson

  I have written a WCF service that returns 'semi-private' data concerning peoples name, addresses and phone numbers. By semi-private, I mean that there is a username and password to access the data, and the data is meant to be secured in transit. However, IMHO noone is going to expend any energy trying to obtain the data, as it is mostly available in the public phone book anyway etc. At some level, the security is a bit of security 'theatre' to tick some boxes imposed on us by government entities. The client end of the service is an application which is given out to registered 'users' to run within their own IT setups. We have no control over the IT of the users - and in fact they often tell us to 'go jump' if we put too many requirements on their systems. One problem we have been encountering is numerous users that have system clocks that are not accurate. This can either be caused by a genuine slow/fast clocks, or more than likely a timezone or daylight savings zone error (putting their machine an hour off the 'real' time). A feature of the WCF bindings we are using is that they rely on the notion of time to detect replay attacks etc. <wsHttpBinding> <binding name="normalWsBinding" maxBufferPoolSize="524288" maxReceivedMessageSize="655360"> <reliableSession enabled="false" /> <security mode="Message"> <message clientCredentialType="UserName" negotiateServiceCredential="false" algorithmSuite="Default" establishSecurityContext="false" /> </security> </binding> </wsHttpBinding> The inaccurate client clocks cause security exceptions to be thrown and unhappy users. Other than suggesting users correct their clocks, we know that we can increase the clock skew of the security bindings. http://www.danrigsby.com/blog/index.php/2008/08/26/changing-the-default-clock-skew-in-wcf/ My question is, what are the real practical security ramifications of increasing the skew to say 2 hours? If an attacker can perform some sort of replay attack, why would a clock skew window of 5 minutes be necessarily safer than 2 hours? I presume performing any attack with security mode of 'message' requires more than just capturing some data at a proxy and sending the data back in again to 'replay' the call? In a situation like mine where data is only 'read' by the users, are there indeed any security ramifications at all to allowing 'replay' attacks?

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• CACLS Confusion

  - by codeulike

  During my NSIS setup script for a WinForms app, I use the following CACLS command to give the Users group full rights to a subfolder: Exec 'CACLS "$INSTDIR\SubFolder" /E /T /C /G "Users":F' So in effect the CACLS command executed is something like: CACLS "c:\Program Files\MyApp\SubFolder" /E /T /C /G "Users":F When I then look at the Folder permissions in Windows Explorer (right click on the folder and choose Properties, go to the Security tab), the correct permissions are there but they are uneditable. Furthermore, clicking the Advanced button for the 'Advanced Security Settings' shows that SubFolder is inheriting the "Users" group permissions from a 'Parent Object', but what is that Parent Object, because its not the folder above. Why are the permissions added by CACLS uneditable, and why are they inherited from nonexistent parent object? I thinking I may have set the options on CACLS wrong. I'm on Windows XP.

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• get current logged in userID in aspnet mvc membership

  - by FosterZ

  hi, i am trying to show a list of users of my application "school", when admin logs in then he can view all the users in list but when school principals logins, he should get only users of his school, So i thought to get the current loggedIn userId first and then by that userId i'll get schoolId since userId is foreign key in school table...once i'll get the schoolId i can show the members of that school. But my problem is how to get the UserID of currently loggedIn. I'm using MVC 1.0 Asp.Net -- "Membership" if my logic above is wrong then please tell me the alternate good idea, so that principal can see only his users list..

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• Solaris 11 pkg fix is my new friend

  - by user12611829

  While putting together some examples of the Solaris 11 Automated Installer (AI), I managed to really mess up my system, to the point where AI was completely unusable. This was my fault as a combination of unfortunate incidents left some remnants that were causing problems, so I tried to clean things up. Unsuccessfully. Perhaps that was a bad idea (OK, it was a terrible idea), but this is Solaris 11 and there are a few more tricks in the sysadmin toolbox. Here's what I did. # rm -rf /install/* # rm -rf /var/ai # installadm create-service -n solaris11-x86 --imagepath /install/solaris11-x86 \ -s [email protected] Warning: Service svc:/network/dns/multicast:default is not online. Installation services will not be advertised via multicast DNS. Creating service from: [email protected] DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 1/1 130/130 264.4/264.4 0B/s PHASE ITEMS Installing new actions 284/284 Updating package state database Done Updating image state Done Creating fast lookup database Done Reading search index Done Updating search index 1/1 Creating i386 service: solaris11-x86 Image path: /install/solaris11-x86 So far so good. Then comes an oops..... setup-service[168]: cd: /var/ai//service/.conf-templ: [No such file or directory] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This is where you generally say a few things to yourself, and then promise to quit deleting configuration files and directories when you don't know what you are doing. Then you recall that the new Solaris 11 packaging system has some ability to correct common mistakes (like the one I just made). Let's give it a try. # pkg fix installadm Verifying: pkg://solaris/install/installadm ERROR dir: var/ai Group: 'root (0)' should be 'sys (3)' dir: var/ai/ai-webserver Missing: directory does not exist dir: var/ai/ai-webserver/compatibility-configuration Missing: directory does not exist dir: var/ai/ai-webserver/conf.d Missing: directory does not exist dir: var/ai/image-server Group: 'root (0)' should be 'sys (3)' dir: var/ai/image-server/cgi-bin Missing: directory does not exist dir: var/ai/image-server/images Group: 'root (0)' should be 'sys (3)' dir: var/ai/image-server/logs Missing: directory does not exist dir: var/ai/profile Missing: directory does not exist dir: var/ai/service Group: 'root (0)' should be 'sys (3)' dir: var/ai/service/.conf-templ Missing: directory does not exist dir: var/ai/service/.conf-templ/AI_data Missing: directory does not exist dir: var/ai/service/.conf-templ/AI_files Missing: directory does not exist file: var/ai/ai-webserver/ai-httpd-templ.conf Missing: regular file does not exist file: var/ai/service/.conf-templ/AI.db Missing: regular file does not exist file: var/ai/image-server/cgi-bin/cgi_get_manifest.py Missing: regular file does not exist Created ZFS snapshot: 2012-12-11-21:09:53 Repairing: pkg://solaris/install/installadm Creating Plan (Evaluating mediators): | DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 1/1 3/3 0.0/0.0 0B/s PHASE ITEMS Updating modified actions 16/16 Updating image state Done Creating fast lookup database Done In just a few moments, IPS found the missing files and incorrect ownerships/permissions. Instead of reinstalling the system, or falling back to an earlier Live Upgrade boot environment, I was able to create my AI services and now all is well. # installadm create-service -n solaris11-x86 --imagepath /install/solaris11-x86 \ -s [email protected] Warning: Service svc:/network/dns/multicast:default is not online. Installation services will not be advertised via multicast DNS. Creating service from: [email protected] DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 1/1 130/130 264.4/264.4 0B/s PHASE ITEMS Installing new actions 284/284 Updating package state database Done Updating image state Done Creating fast lookup database Done Reading search index Done Updating search index 1/1 Creating i386 service: solaris11-x86 Image path: /install/solaris11-x86 Refreshing install services Warning: mDNS registry of service solaris11-x86 could not be verified. Creating default-i386 alias Setting the default PXE bootfile(s) in the local DHCP configuration to: bios clients (arch 00:00): default-i386/boot/grub/pxegrub Refreshing install services Warning: mDNS registry of service default-i386 could not be verified. # installadm create-service -n solaris11u1-x86 --imagepath /install/solaris11u1-x86 \ -s [email protected] Warning: Service svc:/network/dns/multicast:default is not online. Installation services will not be advertised via multicast DNS. Creating service from: [email protected] DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 1/1 514/514 292.3/292.3 0B/s PHASE ITEMS Installing new actions 661/661 Updating package state database Done Updating image state Done Creating fast lookup database Done Reading search index Done Updating search index 1/1 Creating i386 service: solaris11u1-x86 Image path: /install/solaris11u1-x86 Refreshing install services Warning: mDNS registry of service solaris11u1-x86 could not be verified. # installadm list Service Name Alias Of Status Arch Image Path ------------ -------- ------ ---- ---------- default-i386 solaris11-x86 on i386 /install/solaris11-x86 solaris11-x86 - on i386 /install/solaris11-x86 solaris11u1-x86 - on i386 /install/solaris11u1-x86 This is way way better than pkgchk -f in Solaris 10. I'm really beginning to like this new IPS packaging system.

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• Rails single table inheritance/subclass find condition in parent

  - by slythic

  Hi all, I have a table called Users (class User < ActiveRecord::Base) and a subclass/STI of it for Clients (class Client < User). Client "filtering" works as expected, in other words Client.find(:all) works to find all the clients. However, for users I need to filter the result to only find users that are NOT clients (where type is null or blank). I've tried the following in my index controller but no matter what I put for the type it returns all users regardless of type. User.find(:all, :conditions => { :type => nil }, :order => 'name') Any clue on how to get this condition to work? Thanks!

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• Django Admin Form for Many to many relationship

  - by Anand

  I have a many to many relationship between 2 tables Users an Domains. I have defined this relationship in the Domains class. So in the admin interface I see the Users when I am viewing Domains. But I do not see Domains when I am viewing Users. How can I achieve this.

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• Synchronizing two SQL Server databases using MS Sync Framework

  - by Immortal

  I have one central SQL Server database which can be offline from time to time. I have a desktop application using Local DB Cache (SQL CE) to synchronize with the central database and I also have a web application with its own SQL Server that I'd also would like to keep synchronized. All synchronizations must be bidirectional. Is there a way to synchronize my central database with web application's database in the same way as I synchronize my central database with desktop client? I know about collaboration scenarios and peer-to-peer synchronization but I would like to avoid manual provisioning of databases. I'd like to use integrated sql server 2008 change tracking just like in the SQL CE <-- SQL Server scenario.

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• 401 Unauthorized in Tomcat

  - by Stardust

  Hello, I'm using Tomcat 6.0 as a webserver, and I'm trying to open tomcat manager page, but whenever I enter the username as specified in tomcat-users.xml file, I'm getting an error as: **401 Unauthorized** Here's my tomcat-users.xml file: <tomcat-users> <role rolename="manager"/> <user name="admin" password="" roles="admin,manager" /> </tomcat-users> I restart the tomcat, but it has not helped me. Could someone please tell me what's going on wrong?

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• vsftpd not allowing uploads. 550 response

  - by Josh

  I've set vsftpd up on a centos box. I keep trying to upload files but I keep getting "550 Failed to change directory" and "550 Could not get file size." Here's my vsftpd.conf # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=YES # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES anon_other_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file xferlog_std_format=NO # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=YES # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd whith two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES log_ftp_protocol=YES banner_file=/etc/vsftpd/issue local_root=/var/www guest_enable=YES guest_username=ftpusr ftp_username=nobody

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• How to implement a Digg-like algorithm?

  - by Niklas

  Hi, How to implement a website with a recommendation system similar to stackoverflow/digg/reddit? I.e., users submit content and the website needs to calculate some sort of "hotness" according to how popular the item is. The flow is as follows: Users submit content Other users view and vote on the content (assume 90% of the users only views content and 10% actively votes up or down on content) New content is continuously submitted How do I implement an algorithm that calculates the "hotness" of a submitted item, preferably in real-time? Are there any best-practices or design patterns? I would assume that the algorithm takes the following into consideration: When an item was submitted When each vote was cast When the item was viewed E.g. an item that gets a constant trickle of votes would stay somewhat "hot" constantly while an item that receives a burst of votes when it is first submitted will jump to the top of the "hotness"-list but then fall down as the votes stop coming in. (I am using a MySQL+PHP but I am interested in general design patterns).

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• How to save, retrieve and draw an image using Java and PostgreSQL?

  - by spderosso

  Given an object X; I want this object to have an image. The image must be stored in the database. I can't store the path, the actual image must be in the database. My question can be answered by answering the following subquestions: a). What type of field should I put in the database? (e.g VARCHAR) b) What type of object should I use for storing and manipulating the image (at an object layer)? (e.g java.awt.Image) c) How do I create an object of the type selected (answer of question b) from the data obtained from the database? d) How do I save an object of the type selected (answer of question b) to the database? e) How do I draw the image on a web page? I am using PostgreSQL, Java and it is a web application. Thanks!

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