all.
I'm using DBExpress and C++ Builder(Delphi) 2007 and MySQL, firebird , ...
I'd like to make win 32 application which use Database(located on my web server).
I tried using DBExpress (TSQLConnection for MySQL), it's so so slow...
and I tried local database then upload/download using Indy..
but it was not good and little complicated.
So what is the base way to use web-based database for win 32 application?
Do you have any experience? or any document or any comment will be so so graceful..
thanks a lot..
Database connections via an Internet link (using a VPN or not) are slow - you are perfectly right. The main reason IMHO is the "ping" delay of every request, which is very low on a local network, and much higher via Internet. So direct connection is not a good idea.
In latest versions of Delphi, you have the DataSnap components, which is the new "standard" (or Embarcadero recommended) way of doing remote access (including web access). Even if it was found at first to be a bit limited, the latest versions are perfectly usable, and are becoming a key product for cross-platform application building with Delphi. But it is not available for Delphi 2007.
One much matured product (and available for Delphi 2007) is Data Abstract:
Data Abstract is a framework for building database-driven applications
using the multi-tier data access model, for a variety of platforms.
Of course, this is not free, but this is a proven and efficient solution.
You may also take a look at our Client-Server ORM, which can connect to any DB, and is able to implement a RESTful SOA architecture with Delphi 2007, even without using the ORM part - that is, you can use your existing DBExpress-based source code, and expose easily some web interfaces to the data. It is Open Source, and uses JSON as communication format over a secured authentication mechanism. There is a lot of documentation included (more than 700 pages of PDF), which also tries to introduce to the SOA world.
Take a look at Datasnap: info
You need a data access library, which offers features:
Thread safety. In general, you will need to use a dedicated connection for each thread.
Connection pooling. To make connection creation (what is needed for (1)) fast, there must be a connection pool.
Fast execute SQL command, open result set, fetch capabilities.
Tracing. With any one library you may run into performance issues. You need a tool to see what is going on wrong. For that you will need to see and analyze the client and server communication.
Result set caching and ability to read it simultaneously from different threads. You may have few read-only tables, which you will fetch once and cache in your application. But you will need a machanism to read this data from threads. Kind of InMemTable cloning.
My answer is biased, but you may consider AnyDAC. It has all these and many other features.
PS: dbExpress should work too. Try to find first the reason for your performance issue, and not a different library. Because the same may happen with other library ...
DB applications over a slow link need a different approach than those using a fast link. You have to be careful about how much data you move around, and about how many roundtrips your application perform.
Usually an approach when the needed subset is cached on the client, modified, and the applied to the database is preferrable (of course if changes do not neeed to be seen immediately, and the chances of conflicts are low).
No middleware will help you much if the application is not designed with handling a slow link in mind.
Related
I am working on a network project and already using mysql as my backend. The project is coded in c++. When my data becomes pretty large, its takes a lot of time to retrieve data from mysql. Hence I was exploring other databases and came across neo4j. After reading a lot of stuff on internet about neo4j and I have few queries. My core requirement of my project is high performance and availability which I am not getting when my database becomes huge.
My questions:
I am a little hesitant in using neo4j since I have read on internet at places that it does not perform better than mysql. Is it true?
There are no c++ neo4j drivers and can be accessed only via rest apis. Will it make my project even slower as it will be now a http request and response?
can we run neo4j on solaris as my server for the project will be solaris?
Disclaimer: My answer might be biased since I'm working for Neo Technology. Nevertheless I will stay as objective as possible.
Regarding your questions:
It totally depends on your use case if a graph database are a relational database performs better. A graph database excels when you run local queries (e.g. "which are the friends of my friends). By local query I'm referring to a case where you start at one or more bound nodes and then traverse through the graph. For global queries (e.g. "what is the average age of people in the db") a graph database can perform at the same level a relational but will not be significantly faster. However, if your global queries need to do a lot of traversals, the benefit of a graph database will also be significant.
No, using your language's HTTP capabilities will not be slower compared to using a driver. Most of the drivers add some convenience layer(s) for creating the request and parsing the response, and maybe some caching.
Neo4j as a JVM based database can run on any JVM 7 enabled platform. However Neo Technology's support offering currently covers Linux, Windows and HP-UX. If you need commercial grade support for Solaris please get in touch with me or my colleagues directly.
I come from the cliche land of PHP and MySQL on Dreamhost. BUT! I am also a javascript jenie and I've been dying to get on the Node.js train. In my reading I've discovered inadvertently a NoSQL solution called Redis!
With my shared web host and limited server experience (I know how to install Linux on one of my old dell's and do some basic server admin) how can I get started using Redis and Node.js? and the next best question is -- what does one even use Redis for? What situation would Redis be better suited than MySQL? And does Node.js remove the necessity for Apache? If so why do developers recommend using NGINX server?
Lots of questions but there doesnt seem to be a solid source out there with this info all in one place!
Thanks again for your guidance and feedback!
NoSQL is just an inadequate buzz word.
I'll attempt to answer the latter part of the question.
Redis is a key-value store database system. Speed is its primary objective, so most of its use comes from event driven implementations (as it goes over in its reddit tutorial).
It excels at areas like logging, message transactions, and other reactive processes.
Node.js on the other hand is mainly for independent HTTP transactions. It is basically used to serve content (much like a web server, but Node.js really wouldn't be necessarily public facing) very fast which makes it useful for backend business logic applications.
For example, having a C program calculate stock values and having Node.js serve the content for another internal application to retrieve or using Node.js to serve a web page one is developing so one's coworkers can view it internally.
It really excels as a middleman between applications.
Redis
Redis is an in-memory datastore : All your data are stored in the memory meaning that a huge database means huge memory usage, but with really fast access and lookup.
It is also a key-value store : You don't have any realtionships, or queries to retrieve your data. You can only set a key value pair, and retreive it by its id. (Redis also provides useful types such as sets and hashes).
These particularities makes Redis really well suited for storing sessions in a web application, creating indexes on a database, handling real-time data like analytics.
So if you need something that will "replace" MySQL for storing your basic application models I suggest you try something like MongoDB, Riak or CouchDB that are document store.
Document stores manages your data as something analogous to JSON objects (I know it's a huge shortcut).
Read this article if you want to know more about popular nosql databases.
Node.js
Node.js provides asynchrous I/O for the V8 JavaScript engine.
When you run a node server, it listens on a port on your machine (e.g. 3000). It does not do any sort of Domain name resolution and Virtual Host handling so you have to use a http server with a proxy such as Apache or nginx.
Choosing over nginx in production is a matter of performance, and I find it easier to use. But I suggest you use the one you're the most comfortable with.
To get started with it just install them and start playing with it. HowToNode
You can get a free plan from https://redistogo.com/ - it is a hosted redis database instance.
Quick intro to redis data types and basic commands is available here - http://redis.io/topics/data-types-intro.
A good comparison of when to use what is here - http://playbook.thoughtbot.com/choosing-platforms/databases/
I have a prickly design issue regarding the choice of database technologies to use for a group of new applications. The final suite of applications would have the following database requirements...
Central databases (more than one database) using mysql (must be mysql due to justhost.com).
An application to be written which accesses the multiple mysql databases on the web host. This application will also write to local serverless database (sqlite/firebird/vistadb/whatever).
Different flavors of this application will be created for windows (.NET), windows mobile, android if possible, iphone if possible.
So, the design task is to minimise the quantity of code to achieve this. This is going to be tricky since the languages used are already c# / java (android) and objc (iphone). Not too worried about that, but can the work required to implement the various database access layers be minimised?
The serverless database will hold similar data to the mysql server, so some kind of inheritance in the DAL would be useful.
Looking at hibernate/nhibernate and there is linq to whatever. So many choices!
Get a better host. Seriously - SQL Server hosts don't cost that much more. An hour development time possibly per month - and that is already non-conervative.
Otherwise - throw out stuff you do not need. Neutralize languages to one. If that is an internet access stuff, check out OData for exposing data - nice nidependant protocol
The resit sis architecture. and LINQ (2Sql) sucks - compared to nhibernate ;)
but can the database access layer be reused?
Yes, it can be, but you have to carefully create a loosely coupled datalayer with no dependency on other parts.
I write MS Access / VB / SQL Applications, customized. One of my clients has a truly massive Access application I wrote them, and their number of active users have just expanded to over 15. Running into more data corruption issues, I am recommending they port to an SQL backend for stability. (Of course).
They would prefer to invest in a less expensive option and go with a Linux Server. I have used ODBC to hook an Access front to SQL backend plenty of times. But I have never touched Postgre.
I am looking for comprehensive detailed data on if this is a good strategic solution for a design plan, or if it is even a possibility. Perhaps there is an easier solution and I am barking up the wrong tree...
Yes, this is absolutely possible. I've not run into any major issues - the biggest I had was getting the Postgres boolean's to match up correctly - but it all depends on how you setup the ODBC connection and the actual application. I've found the ODBC connection stable and usable. If you really anticipate a larger number of users, you really ought to consider rewriting the whole app into something other than Access.
Overall, I'd definitely recommend Postgres as a backend via ODBC. Once you get used to a few of the differences, a lot of people really end up enjoying Postgres as a DB.
I've just started working on a project that will involve multiple people entering data from multiple geographic locations. I've been asked to prepare forms in Access 2003 to facilitate this data entry. Right now, copies of the DB (with my tables and forms) will be distributed to each of the sites, returned to me, and then I get to hammer them all together. I can do that, but I'm hoping that there is a better way - if not for this project, then for future projects.
We don't have any funding for real programming support, so it's up to me. I am comfortable with HTML, CSS, and SQL, have played around with Django a fair bit, and am a decently fast learner. I don't have much time to design forms, but they don't have to actually function for a few months.
I think there are some substantial benefits to web-based forms (primary keys are set centrally, I can monitor data entry, form changes are immediately and universally deployed, I don't have to do tech support for different versions of Access). But I'd love to hear from voices of experience about the actual benefits and hazards of this stuff.
This is very lightweight data entry - three forms attached to three tables, linked by person ID, certainly under 5000 total records. While this is hardly bank account-type information, I do take the security of these data seriously, so that's an additional consideration. Any specific technology recommendations?
Options that involve Access:
use Jet replication. If the machines where the data editing is being done can be connected via wired LAN to the central network, synchronization would be very easy to implement (via the simple Direct Synchronization, only a couple lines of code). If not (as seems the case), it's an order of magnitude more complex and requires significint setup of the remote systems. For an ongoing project, it can be a very good solution. For a one off, not so much. See the Jet Replication Wiki for lots of information on Jet Replication. One advantage of this solution is that it works completely offline (i.e., no Internet connection).
use Access for the front end and SQL Server (or some other server database) for the back end. Provide a mechanism for remote users to connect to the centrally-hosted database server, either over VPN (preferred) or by exposing a non-standard port to the open Internet (not recommended). For lightweight editing, this shouldn't require overmuch optimization of the Access app to get a usable application, but it isn't going to be as fast as a local connection, and how slow will depend on the users' Internet connections. This solution does require an Internet connection to be used.
host the Access app on a Windows Terminal Server. If the infrastructure is available and there's a budget for CALs (or if the CALs are already in place), this is a very, very easy way to share an Access app. Like #2, this requires an Internet connection, but it puts all the administration in one central location and requires no development beyond what's already been done to create the existing Access app.
For non-Access solutions, it's a matter of building a web front end. For the size app you've outlined, that sounds pretty simple for the person who already knows how to do that, not so much for the person who doesn't!
Even though I'm an Access developer, based on what you've outlined, I'd probably recommend a light-weight web-based front end, as simple as possible with no bells and whistles. I use PHP, but obviously any web scripting environment would be appropriate.
I agree with David: a web-based solution sounds the most suitable.
I use CodeCharge Studio for that: it has a very Access-like interface, lots of wizards to create online forms etc. CCS offers a number of different programming languages; I use PHP, as part of a LAMP stack.